woodland management home study module module 15: pests...

Manual HSC 2012 – 3

W o o d l A N d M A N Ag e M e N t H o M e S t u dy M o d u l e

Module 15: Pests of the

Acadian Forest

N S D N R W o o D l A N D M A N A g e M e N t H o M e S t u Dy M o D u l e

MANuAl HSC 2012 – 3

MoDule 15: Pests of the

Acadian Forest

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Written by Jacqueline gordon and Jeffrey ogden, Forest Health Specialists with DNR Forest Protection Division, and Sheena Masson, Writer and Researcher.

the authors would like to thank the reviewers that have spent significant time offering helpful suggestions for improvement of the text: Simon Mutabazi, NSDNR Extension Forester; tim Whynot, Manager, Private Lands, Stewardship and Outreach; Katherine ogden, Assistant Curator and Registrar, NS Museum; eric georgeson, Assistant Professor, Dalhousie University; Jeana Macleod, Environmental Policy Student, MUN; Margaret-Anne Moulton, DNR Administration; and Melanie Henley, DNR Administrative Support.

Any errors or omissions are the responsibility of the authors, who would welcome comments and suggestions. All photos and illustrations originated with the author, except where credit is given to NSDNR.

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Table of Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Lesson One: getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Impacts of Pests on your Woodland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Identifying Pests by Host tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Parts of the tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Insects types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Insect life Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Invasive Alien Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Integrated Pest Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Insects and Climate Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12What to Do if your Woodland is Infected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Review and Quiz 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Lesson Two: Softwood Pests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16What to look For . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Insect types Found on Five Softwood tree Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Some Control options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Review and Quiz 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Lesson Three: Hardwood Pests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22What to look For . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Insect types Found on Five Hardwood tree Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Some Control options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Review and Quiz 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Lesson Four: A Quick guide to Sample Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Insect Still on Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Insect Cannot be Found . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Collecting Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30Case Study one . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Case Study two . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Review and Quiz 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

A Information Sources and References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

B glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

C Photo Credits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

D exercise and Quiz Answers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

1

For many of us, the “Pests of the Acadian Forest” are simply mosquitoes and black flies. We may not be as familiar with other insect pests. As woodland owners, you may know about tree species and silviculture treatments but not as much about pests unless there has been an outbreak of some kind on your land. For some owners, it may be their first encounter with insect damage and trying to understand it brings them to this module.

Insects are everywhere on your woodland – in the air, on the trees, and in the soil. Each one has a purpose and sometimes their purpose is at odds with your goals for a woodland.

Many insects have a beneficial role in the forest ecology but this module focuses on the ones that can cause unwanted effects on your woodland. Pest activity can result in economic loss, habitat loss and unsightly stands. Damage may also be caused by tree diseases but these are not covered in this module.

This module begins with an introduction to pest impacts, good and bad, and how pests are classified and managed. It then examines softwoods and hardwoods separately, and what to look for in terms of insect damage. It also explains how to collect and send samples in case you need further help identifying the insect. A glossary of terms referred to throughout the module is provided in Appendix B.

It can be alarming for a woodland owner to notice insect damage in the trees on their woodland. You may wonder if the trees will survive and if the infestation will spread to other parts of your woodland. You may want to know what insect is causing the damage and what you can do about it.

The objectives of this module are : • To recognize the signs and symptoms of insect

damage• To learn the basics about insects that could cause

damage • To learn about treatments and how to get help if

you need it

A companion field guide has been developed to use outside on the woodland. It has colour photos and descriptions of over 50 common forest pests. These pest descriptions are divided into two groups: those pests that affect softwood and those that affect hardwood trees.

Studying the module beforehand will help you use the field guide. Once you become familiar with the basic insect types and damage in this module, you can use the guide to identify the insects causing damage to your trees and some treatment options.

INTRODUCTION

“ I swear these blackflies get smarter every year.”

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To get started on understanding pest damage, you need to know not only about the pests themselves but also about the trees they infect. For this reason, Lesson One provides a quick review of tree species and tree parts as well as some basic information on pests. Together these build a useful background for understanding the terms and processes you’ll find in this module, in the field guide, and in your search for answers.

This Lesson looks at: • Impacts of Insect Activity• Identifying Pests by Host Tree• Parts of the Tree• Insect Types• Insect Life Cycles• Invasive Alien Species• Integrated Pest Management• Insects and Climate Change • What to do if your woodland is infected

(a general overview)

The most important parts of the identification process are knowing what species of trees are infected and a visual inspection. In most cases (about 70%), the insect will have left the infected trees by the time the damage is noticed and only the effects remain. The insect may be travelling to other trees; however, it may be possible to prevent or slow down further damage.

Positive imPacts

song sparrow eating insect

Insects play necessary and beneficial roles in the forest ecology. One of the more obvious roles is insect pollination which creates new seeds. The forest is also renewed when insect activity kills old and weak trees allowing new growth. The dead trees are recycled by insects into soil and can be used as habitat by certain birds, reptiles, amphibians and mammals. Insects are also an important food source for many species of wildlife. Some insects feed on those insects that are harmful to the woodland helping to reduce the population of harmful insects.

leSSoN 1 Getting Started

Positive imPActs

Pollination Renewing

Recycling Habitat improvement

Food source

NeGAtive imPActs

economic loss Unattractive

Recreational loss Habitat Decline

Displace tree species

Insects have both positive and negative impacts on the woodland.

Impacts of Insect Activity

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Negative imPacts

stand showing signs of insect damage

Insect activity also can have negative impacts in the forest, especially if the damage becomes widespread. It can reduce growth, cause deformity, and dieback, resulting in reduced tree value for the woodland owner. Infected Christmas trees may not be sellable due to shipping restrictions. An infected area may look unattractive and be less appealing for hiking or other outdoor activities. If trees in a large area die, recreational use and wildlife habitat may be reduced. The existing tree species could be displaced and replaced by less desirable ones.

Normal versus uNaccePtableSome insect damage is normal in a balanced ecosystem. A few trees damaged or killed on your woodland is probably ok, but when a population grows bigger and feeds over a greater area, the amount of damage can become unacceptable. This is often due to having a large available food source. It can also be triggered by favourable climate conditions. The insects and damage may affect neighbouring properties as well or much bigger areas. The outbreak boundaries follow the areas of food source and cross property lines.

Other causes of damageIt’s not always an insect pest that is causing a tree or stand to look “sick”. As mentioned in the introduction, there are tree diseases that can look like insect damage. For example, ash trees can get a orange spot on the leaves caused by a rust disease that is similar to damage caused by an insect.

In some trees, the insect and disease work together. With Dutch Elm disease, an insect carries the fungus that later kills the tree. In beech trees, damage caused by feeding insects allows a fungus to enter later and damage or kill the tree. A suitable treatment may target the insect before the disease can spread.

Overly dry or wet soil can also cause trees to look damaged. After a wet season, water can pool in low areas and make Christmas trees look yellow. In a dry season, needles can fall off and leaves can discolour. Once the tree is weakened, it may then be more susceptible to insect pests.

Identifying Pests by Host Tree

ideNtify the host treeA first step to identify the pest is to determine the tree species “hosting” the insect on your woodland. Some insects have a preferred host species. This can be thought of as the pest’s “ favourite food”. The pest will sometimes feed on other tree species if they are nearby or the favourite food runs out. This means you may need to identify several host species on your woodland.

The mix of trees found in Nova Scotia, southern New Brunswick and Prince Edward Island is called the Acadian Forest. It begins in New York State and stretches through New Hampshire, Vermont and Maine to the Maritimes. Pockets of other forest types and some non-native trees can be found but Acadian forest is predominant.

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The number of native trees in the Acadian forest is less compared to southern regions. There are 30 native trees in the Acadian forest, some more abundant than others. Nova Scotia also has about 15 introduced species such as Norway spruce, and 15 shrubs or bushes such as pin cherry that can grow to tree size.

softwood or hardwood

red spruce tree; (insert) maple leaf with feeding damage

A basic division for identifying trees is softwoods and hardwoods. Softwoods, also known as coniferous trees, always have needles on them. That is why they are called “evergreens”. The needles do shed - just look at the forest floor under a pine tree - but not all at once. The exception is the tamarack tree (also known as larch or hackmatack) which turns yellow in the fall and sheds its needles. The more common softwoods in Nova Scotia are spruce, fir, pine and hemlock.

Hardwoods, also known as deciduous trees, lose their leaves every fall after turning from green to a show of red, yellow and orange. They are usually bare in winter (a few dead leaves sometimes hang on) and bud out again in the spring. The more common hardwoods in Nova Scotia are maple, birch, poplar and oak.

tree sPecies Many woodland owners will already know the more common kinds of softwood and hardwood trees but may not be as familiar with the various groups or species of trees, for example red, white and black spruce. These can be easily identified by examining

the bark, needles , leaves and/or seeds. Module One “Introduction to Silviculture” has descriptions and sketches of nine softwood species and eleven hardwood trees to guide you. Another good resource is the book, Trees of Nova Scotia. (See Appendix A).

NamiNg Pests

whitemarked tussock moth

Some pests are named for their appearance such as the whitemarked tussock moth. Others are named for the damage they cause such as the seedling debarking weevil. Many pests are named after a tree species that they damage such as the spruce beetle.

However in the complex world of insects, naming is far from standard. The pest and the tree species it is named after may not have a one-on-one relationship.

some examples: 1 Many pests will attack other species in addition

to the tree species in their name. That species may be the preferred host but not the only host. An example is the balsam fir sawfly that prefers Balsam fir but also feeds on spruce.

2 For other pests, the preferred host may not be reflected in the name. The spruce budworm, for example, prefers Balsam fir but will also feed on spruce.

3 The pest host may not apply to the Acadian Forest. The hemlock looper prefers hemlock in western Canada but likes Balsam fir in eastern Canada.

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These examples may be helpful as you read about pest names and try to determine which one is causing the damage.

christmas tree PestsChristmas trees are an important industry in Nova Scotia. Most of them are Balsam fir which has more than its fair share of pests. In a Christmas tree stand, there is a concentrated food source that can encourage population growth and certain pests can cause considerable damage. The field guide includes descriptions of the more common Balsam fir pests. For producers who need more detailed information

and treatment options, material is available on line and in print. (See Appendix A.)

Parts of the Tree – Softwood and HardwoodEach insect species tends to attack a specific part of a tree like the needles or the bark. Since this information is part of the identification process, tree parts are reviewed below for both softwood and hardwood trees. The insect world is full of exceptions and a few pests will feed on more than one part of the tree.

hardwood tree

bUDs

NeeDles oR leAves

bRANcHes

stem AND tRUNk

Roots

NOTE: While many pests feed on only softwood or hardwood, some feed on both.

softwood tree

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For studying insect damage in this module, the tree is divided into FIVE parts:

1: buds

2: Needles or leaves

3: braNches

4: truNk or stem

5: roots

Insect Types The insect world is complex with over one million species of insects that change appearance as they go through their life cycle. Fortunately, the most common insects found causing damage to your woodland can be grouped into five general types that most people can recognize in the adult stage. In general, insects do the most damage during the larval stage.

1 beetles Larval damage by beetles may include boring under bark and into stems, and foliage feeding. Adults may cause damage to stems during egg laying (ovipositing) or while feeding on foliage, bark or stems.

longhorn beetle

2 mothsMoths do all of their damage in the larval stage by feeding directly on the foliage, mining the foliage or boring into stems. Adults for the most part do not damage vegetation.

rosy maple moth

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3 fliesAdult flies do very little damage and are responsible only for egg laying and reproduction. Fly larvae can cause a variety of damage including gall production on stems and foliage.

galls of the balsam fir gall midge

4 wasPs Wasp pests include larval defoliators, gall makers, foliage miners and wood borers. Adult pest species may cause damage to stems and foliage during egg laying as well as some minor feeding damage.

larvae of the balsam fir sawfly

5 true bugs, aPhids or hoPPersBoth immature and adult stages of these insects cause damage. Immature stages are called nymphs – miniature versions of the adults – and have no true larval stage. Nymphs feed in a way similar to the adult, causing damage by sucking plant juices from either foliage or stems.

alder woolly aphids

6 NoN iNsect forest Pests

mites

Insects are defined as having six legs, three body parts, an exoskeleton (a hard shell outside the body) and most have wings. The classification does not include spiders, ticks, mites or certain other animals similar to insects. Mites however are discussed in this module as they are a significant pest of our forest.

Mites are not insects and are more closely related to spiders. They can however cause significant damage to foliage during feeding with their sucking mouthparts.

galls of a mite on maple

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Insect descriptions include the habits and appearance of the insect during all stages of its life cycle. Knowing what a species looks like during each stage will help you identify the insect if it is still present. Recognizing the insect stage is necessary for timing a treatment to prevent or limit further damage.

four stages iN the life cycleInsects go through four stages in their life cycle. You may remember these from school days.

Life cycle of the Spruce budworm showing timing of 4 stages

oNe: The Egg Egg masses are laid individually or in masses on the tree host by the adult insect.

tWo A: The Larva The eggs hatch into larvae which resemble small worms or grubs. They feed heavily preparing for the next stage. Most damage is caused during this stage.

oR tWo B: The Nymph In other insect groups, the egg hatches into a nymph which resemble a small, wingless version of the adult. They feed like the adults do, getting larger following each growth stage or moult.

tHRee: The Pupa The larva may spin a cocoon and transform during the pupa stage into the adult form. It does not always spin a cocoon. If the immature insect is a nymph (Two B), there is no pupae stage.

FouR: The Adult The adult moth or beetle or other insect type emerges from the pupa. Adult feeding causes the second greatest amount of damage after the larval stage.

spruce budworm moth

spruce budworm larva

spruce budworm pupa

second instar spruce budworm larva

not pictured here

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To add to the complexity, each insect species has its own variations on these four stages. For example, spruce budworm has six larval forms before it makes a pupa. The balsam twig aphid has several adult forms in its life cycle.

This means that each pest looks very different at various stages in its development. Fortunately, research has provided us with specific details on the life cycle of woodland pests.

sample insect Profile All this information – host tree, life history, damage symptoms, and possible controls – is pulled together in the insect description or profile.

For example, here is the profile for the spruce budworm from the Department of Natural Resources web site.

Spruce Budworm

adult spruce budworm moth

Order: Lepidoptera

Family: Tortricidae

Latin Name: Choristoneura fumiferana (Clemens)

Common Names: spruce budworm, eastern spruce budworm

introduction The spruce budworm has caused more damage to Nova Scotian softwood forests than any other insect. Overmature balsam fir is the preferred host and acts as a flash point for rapid population buildup. Populations tend to increase steadily and spread to younger trees. Feeding takes place on the top third of the tree on new shoots. High populations will result in repeated loss of all new foliage which will kill the trees within 3 to 4 years.

life history In late August or September, the eggs hatch, the larvae moult, and overwinter in the second instar. In late April or early May, the larvae (3 mm long) emerge from their hibernacula and begin to feed, mining the needles and buds. A week later they move to feed on the closed buds and any developing shoots. The larvae are fully grown within five weeks. They have black heads and a dark brown body, (18 - 24 mm long). They pupate on the foliage and the adult moths emerge in July to lay eggs which hatch in 2 to 3 weeks. The adults are dull grey with a wingspan of 20 mm.

damage symptoms Defoliated trees over large areas with red foliage; particularly the new foliage on the upper third of the tree.

control options Harvest stands of overmature fir and spruce to remove potential population build up sites. Biological control products are recommended for large forested areas. These will not interfere with naturally occurring parasites and diseases that help control budworm populations.

For ornamental fir and spruces, both biological or contact insecticide can be used. When using a biological insecticide such as Btk (Bacillus thuringiensis var. kurstaki, see glossary), the product should be applied while the larvae are in the open and feeding. Contact insecticides should be applied while the larvae are exposed and not hidden under the bud caps.

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ExErcisE: Read through a few insect profiles to get familiar with the type of information they contain. You can find some on line at the DNR web site, the Canadian Forest Service web site and in the Field Guide. Insectary Notes also has a longer profile in each issue. (see Appendix A for the list of web sites).

Invasive Alien Species Insects may appear on your woodland that are not native to the area and have traveled outside their usual range. These are known as invasive alien species. They may originate from outside Canada or from other parts of Canada. An insect can be alien even if it is native to Canada when it extends beyond its usual geographic range. The term alien refers to shifts across ecosystems, not simply across borders.

brown spruce longhorn beetle

The introduction of these insects is often accidental. The insects can arrive in plants or wood products brought in from other countries. They can spread from their original arrival point to other areas with suitable food. A recent example is the brown spruce longhorn beetle, which is native to Europe. It arrived by sea in the wood of packing crates into the port of Halifax. At first it was found close to the shipping terminal in the trees of Point Pleasant Park but it has now spread to some other areas of the province.

The alien insect becomes known as invasive if it has spread beyond its usual range, adapts to the host

area’s ecosystem and causes extensive damage. The Government of Canada definition is “Invasive alien species (IAS) are plants, animals, aquatic life or micro-organisms that outcompete native species when introduced outside of their natural environment and threaten ecosystems, economy and society.” (2009). From Invasive Species Alliance of NS.

The Gypsy Moth is an example of an invasive alien species. It was imported from Europe to the US over one hundred years ago in an unsuccessful attempt to help the silk industry there. It feeds on more than 400 species of trees and has historically caused serious defoliation to hardwoods in Nova Scotia.

As the climate changes and trade increases, insects are moving into new ranges. Some species have a tough time adapting to the new environment and do not become invasive. Others may do well as they have no natural enemies in the new location, resulting in negative impacts. Like native pests, they can cause extensive damage in pure stands or stands with a high percentage of one species where they find a large available food source.

See Appendix A for more information on the effects of Invasive Alien Species and details on specific insects.

Integrated Pest ManagementBecause the world of pest insects is so complex (both the insects and their habitats), the management of these pests is also a complex and evolving science. In the past, the two main treatments were pesticide spraying and salvage harvesting but now they are just two of many tools available to the landowner.

In integrated pest management, interventions are carried out based on knowledge about what their short and long term impacts might be.

– Canadian Forest Service.

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As knowledge improves, a more integrated approach to pest management has evolved. Integrated Pest Management (IPM) is an effective method to manage forest pests. It looks at all appropriate options considering both the economic and environmental impacts.

By better understanding insect life cycles and their interaction with the environment, new tools are being developed to monitor and, in some cases, reduce the spread of insect pests. These include products that target the behavior and biology of the pest. Improved methods of detection include development of more effective traps and more specific attractants.

pheromone trap

Chemical sprays are being replaced or used along with safer biological products such as viruses and fungi. Some beneficial insects can be used to minimize the damage of pests; this is known as biological control. These biological products can target specific species of pests, reducing the impacts of the sprays on non-target species and sensitive ecosystems.

The effect of some treatments can be hard to predict in the intricate ecology of the forest. In recent years more emphasis is being placed on risk analysis and prevention. It’s a good idea to examine the potential risk a pest may have on your woodland before control

efforts are made. This may reduce the chances that the treatment causes new problems such as eliminating a beneficial insect or prolonging an infestation.

In some cases, costly control measures may not be necessary. Practices such as breaking up the forest age class, promoting a healthy mixed species woodland and selecting pest-resistant varieties are preventative methods that can be very effective, cost-efficient and low risk to the environment.

Managing your woodland for forest pests should no longer consist of a single control method but rather a series of pest management evaluations, decisions and controls. Think of it as having a toolbox full of possible solutions instead of just one hammer.

Insects and Climate ChangeAs science is showing, our climate is changing and this in turn changes our forests. Wetter winters, drier summers and more wind storms can stress the forest and affect which tree species grow well here. More exotic diseases and pests may be an additional stress.

As the climate changes, so do the insects living in the forest. Some may thrive and others may decline. For example, a DNR employee has noticed that the balsam woolly adelgid is now active in the Cape Breton Highlands where it was not found 25 years earlier. He says, “The winters were too cold before and the insects did not survive. Now in 2013, the insect is active in all of the highlands where balsam fir is found. It takes a sustained temperature of about -25C or lower to kill the insect and we rarely see those temperatures anymore.”

As new tree species begin to flourish, new insect species will grow along with them. What does this mean? We have to be aware that these shifts are occurring and learn new ways to adjust our management techniques to address them.

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What to Do if Your Woodland is Infested A woodland infestation can range from mild to severe. The level of damage can be predicted by estimating the number of insects present. For small scale infestations, it may not be necessary to do anything. Damage may be limited to a few trees. If the wood is infected and has the potential to spread, it is common to cut up the wood and remove it or chip it. In a severe case, it may be necessary to do a more extensive cut or use insecticide spray.

two people operating a chipper

What you want to get out of your woodland (your woodland objectives) also influence how you choose to manage the insect infestation. What one woodland owner considers a serious infestation may not be of great concern to another. If your objective is income and an insect is attacking a stand of trees you are growing to sell later, you may want to act quickly. If your objectives for the infected area are recreation or habitat, then an infestation may not affect those objectives as much.

person collecting an insect sample

If the insect is still present, identify the host tree and collect a sample of the insect. Also collect a damage sample if possible, for example a damaged leaf, and also a healthy sample. Lesson Four explains how to collect and send samples. Make a note of the type of damage and walk your woodland to determine how widespread it is. Remember that damage can also be caused by diseases and moisture conditions.

If the insect is not present, you can still narrow it down by identifying the tree host and the damage symptoms. Collect a healthy sample and one showing damage. Lesson Two and Three outline the various kinds of damage, the associated insect types and some control options. Sometimes different insects can cause the same damage but the control options are the same.

Use the field reference guide to try and identify the specific insect. You can also consult with Pest Detection Officers (PDO) at the local DNR offices, the Forest Health Specialists and Entomologist at the DNR Insectary, or a forestry consultant for help with identification and suggested treatments.

The woodland or forest owner – private, municipal, provincial or federal – is responsible for pest management. If your woodland infestation is widespread, it may be that neighbouring lands are also infected since pests follow food and are unfamiliar with property lines. You may want to work with neighbouring landowners on an integrated management approach if the infestation extends beyond your woodland.

14

If there is an infestation on your woodland, try to identify the insect (even if it is gone) to determine what action is needed, if any. The host tree, the appearance of the insect, and the damage it causes are all key factors in identification. By paying attention to signs of infestation, you may be able to prevent damage to your trees or reduce the spread of the insect.

Quiz 1 1. When you notice insect damage on a tree, the insect is still present:

qa) All the time

qb) About 50% the time

qc) About 30% of the time

qd) About 10 % of the time

2. Insect activity has no benefits and is only harmful to the forest.

qTrue qFalse

3. The preferred host tree means:

qa) a softwood tree

qb) a hardwood tree

qc) the insects favourite food

4. Most insects feed on a specific part of a tree.

qTrue qFalse

5. The life cycles of an insect are (in order):

qa) larva or nymph, egg, pupa, adult

qb) egg, larva or nymph, pupa, adult

qc) pupa, egg, larva or nymph, adult

qd) egg, pupa, larva or nymph, adult

Review

15

6. Alien insects

qa) Can come from outside Canada

qb) Can come from other parts of Canada

qc) Are outside their usual ecosystem

qd) All of the above

7. If your woodland is infected, you should:

qa) Cut all the infected wood and remove it

qb) Choose a control option based on your woodland objectives

qc) Use an insecticide spray

qd) Let nature take its course

16

Lesson Two explains what to look for if insects are feeding on softwood trees on your woodland. This will help you narrow down which insect may be feeding there. If a hardwood species is being damaged on your land, skip to Lesson Three for the same kind of process for hardwoods. A few insects will feed on both kinds of trees.

woodland owner examining a stand of fir trees

This lesson begins with what to look for on your woodland in terms of insect damage. This may be what first catches your attention while walking through a softwood stand on your woodland or on an individual tree. You may notice some changes from a distance and others close up. Next, the lesson examines in more detail what activity you may find on various parts of the softwood tree.

What to look for When softwood damage is widespread, it can be quite noticeable from a distance. Anyone travelling in some regions of Nova Scotia in recent years has likely noticed bands of greyish brown dead softwoods trees along the hillsides. One common cause is spruce beetle which prefers mature white spruce and also attacks other species of spruce.

Walking in your woodland, you may notice changes in your softwood trees. The crowns may have thinned so you can now see through them. There may be dead trees with brown needles. The needles may be off colour - yellow or reddish - instead of green. Perhaps branches are beginning to droop.

damage caused by spruce bark beetle

Up close you may notice further signs of damage. On the bark, you may see globs of pitch called pitch tubes that ooze out of holes bored by insects. Other signs include missing needles, dead buds, and clumped twigs or needles. Insects can also create tents or webbing in the branches.

pitch tubes on spruce, a result of spruce bark beetle attack

Sometimes you may see the insect itself such as a caterpillar, feeding on the tree. Insects usually begin feeding in the spring. Make a note of when you first noticed the damage. If it was in June for example, you may find considerably more damage a month later.

leSSoN 2 Softwood Pests

17

1 Buds and

Shoots

• needle or bud deformity

• feeding of needles of bud, often under bud cap

• mining of needles and buds

• terminal shoot kill

damage caused by balsam twig aphid

spruce budworm larva

shoot boring sawfly damage

white pine weevil damage

• gall-making flies can cause deformity of individual needles; feeding of certain aphids can result in twisted needles; or gall making aphids (adelgids) and flies (midges) can enlarge the entire bud as a result of feeding activity and interactions with plant often killing new growth

• early instar moth larvae feed under protective covering of bud caps defoliating new growth

• overwintering, early instar (the stage between two moults) moth larvae bore into sides of buds or terminal stems killing new growth; small sawfly larvae (wasp) bore into new shoots killing the bud

• boring feeding of beetle and moth larvae within terminal shoot

Insect types found on five softwood tree partsIn this section, the tree is studied even more closely. In the chart below, a tree is divided into five parts. Reading down they are: Buds and Shoots, Foliage (Needles), Twig and Branch, Stem or Log, and Root. Reading across the table is the damage you may see, the pest type found feeding there and a few examples. Some pests feed on more than one part of the tree. All these hungry insects are busy boring, chewing, and sucking. This results in certain kinds of visible damage that point in turn to specific insects.

tree Parts damage Pest type example

NAt

uRAl

ReS

ouR

CeS

CAN

ADA,

CAN

ADIA

N

FoRe

St S

eRvI

Ce

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2 Foliage

(Needles)


• defoliated (chewed) needles

• mined needles

• clusters of chewed needles and webbing

• browning of needles

• number of moth larvae feed on current and old growth foliage; several sawfly species (larvae) feed on older needles, often in aggregations of several individuals

• larvae of several small moth species and a few sawfly feed inside needles

• larvae of certain sawfly species construct feeding shelters from chewed needles, silk and frass (excreta)

• damaged caused by sucking feeding of numerous hopper, true bug, aphid and spider mite species

larvae of balsam fir sawfly

damage caused by larch casebearer

webspinning sawfly

aphids on fir

PHot

o: M

IlAN

zuBR

IK,

FoRe

St R

eSeA

RCH

INSt

Itut

e –

Slov

AKIA

19

4 Stem

or Log

3 Twig and

Branch



• twig deformity

• twig and stem death with evidence of exit holes

• In some instances there is no damage evident but pest species could be present feeding on the stem

damage of the spruce gall adelgid

adult longhorn beetle feeding

spittle bug on pine

• gall making aphids (adelgids), beetles and flies (midges) cause stem enlargement and/or deformity as result of feeding and chemical interactions with plant

• feeding bores within the twigs and stems by beetle or moth larvae

• aphids can be found in clusters feeding on the stem; larvae of hoppers enclosed in frothy (spittle) masses; scale insects cluster along stem

• exit holes in trunk with evidence of pitch and/or sawdust

spruce beetle damage• numerous wood boring beetles and wasp that feed both under the bark and into the heart wood of the tree

PHot

o: tI

M tI

gNeR

, vI

RgIN

IA D

ePAR

tMeN

t

oF F

oReS

tRy

20

5 Root

• chew marks around root collar of seedlings

• yellowing of entire tree

root collar feeding

balsam fir root aphid

• root collar debarking beetle feeds at soil surface girdling and eventually killing the seedling

• result of aphids feeding on the roots, deforming and killing roots, often evidence of waxy wool-like substance on roots of younger trees; ground dwelling beetle larvae often feed on the roots of smaller trees


Some control options The insect types mentioned above impact the trees in a woodland to varying degrees. For many, the degree of damage may be determined simply by the weather during a particular year. The added stress of a summer drought, wet spring or harsh winter can intensify the impact of a usually less harmful pest outbreak.

Some pests may be considered more of a visual problem such as galled and deformed needles or the odd stem killed by a web spinning sawfly which can look unattractive. In forested settings, there may be no need for control options for such pests. However, if your business is Christmas trees, an attractive product is your bread and butter and such pests become a more important issue.

For defoliators, control is often necessary when populations get high enough. Knowing what products to use in a specific situation is key to protecting the resource. Chemical or biological insecticides may not be effective if the pest bores into trees, lives in a ball of spittle or mines into needles. Certain products may work very well on moth larvae, such the biological insecticide Btk, but are completely useless on wasp or beetle larvae.

New products include viruses developed specifically to target particular species, chemical mating disruptors and various lures and attractants.

Knowing what control products are available and when, how and if to apply them are key in protecting your woodland. Remember to read and follow the instructions on the label when using any control agent. Proper application and use of recommended personal protective equipment are essential for the safe use and effectiveness of any pesticide.

21

Taking a closer look at the damage to trees on your woodland is the first step to identifying the pest. The tree part and the type of damage are both initial clues. If you decide that a control product is needed, take time to review and select the appropriate option.

Quiz 2 1. Softwood trees with insect damage can have:

qa) brown or yellow needles

qb) thin crowns

qc) drooping branches

qd) any of the above

2. Insects boring holes can cause globes of pitch on the bark.

qTrue qFalse

3. Aphids only feed on one part of the tree.

qTrue qFalse

4. Which type of extreme weather can intensify an insect outbreak?

qa) A dry summer

qb) A wet spring

qc) A cold winter

qd) All of the above

Review

22

Lesson Three guides you through a process of what to look for if insects are feeding on hardwood trees on your woodland. This will help you narrow down which insect may be feeding there. This is a similar process to the one used in Lesson Two for softwoods. A few insects will feed on both kinds of trees.

woodland owner examining a whitemarked tussock moth larva on oak.

Like Lesson Two, this lesson begins with what to look for in terms of insect damage. This may be what first catches your attention walking through a hardwood stand or on an individual tree. You may notice some changes from a distance and others close up. Next, the lesson examines in more detail what you may find on various parts of the hardwood tree.

What to look for Widespread infestation of hardwood trees is less frequent and often less intense than for softwoods in Nova Scotia. For hardwoods, the extent and severity of the damage can be greatly influenced by weather and other factors such as drought or nutrient loss. Any added stress may intensify the damage caused by pests and may contribute to tree mortality.

Walking on your woodland, you may notice changes in your hardwood trees such as wilting leaves, evidence of chewing, yellowing foliage and thinner crowns. You may see dead leaves on the branches or twigs. You may also see tents or webbing created by insects in the branches.

larva of a gypsy moth.

Up close you may notice further signs of damage. Leaves can be stuck together, have spots or be curled up. Insects can chew holes in leaves giving them a shot gun look and later eat the whole leaf. Galls as large as ping pong balls are made by insects for shelter on the leaves or twigs.

Sometimes the insect may still be present, feeding on the tree. Insects usually begin feeding in the spring. Make a note of when you first noticed the damage. Come back a month later and see how much the damage has increased.

leSSoN 3 Hardwood Pests

23

• gall making flies and spider mites can cause deformity of buds as a result of feeding activity and chemical interactions with plant often killing new growth

• feeding of aphids resulting in discoloration and structure damage to shoot

1Buds and

Shoots

Insect types on five hardwood tree partsIn this section, the tree is studied even more closely. The tree is divided into five parts in the chart below for this purpose. Reading down they are: Buds and Shoots, Foliage (leaves), Twig and Branch, Stem or Log, and Root. Reading across are the damage you may see, the pest type found feeding there and a few examples. A few pests will feed on more than one part of the tree. As with the softwoods, these insects are also busy boring, chewing, and sucking. This results in certain kinds of visible damage that point in turn to specific insects.


damage caused by the birch bud gall mite

aphids

• bud deformity

• wilting of new shoots

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2Foliage (leaves)

gypsy moth larvae

damage caused by birch leaf miner

leaf roller damage on poplar

eastern tent caterpillar

damage caused by beech flea weevil

mite galls on maple

• defoliated (chewed) leaves

• skeletonized leaves

• leaves rolled, folded and/or stuck together with silk

• leaves enclosed in tent-like structure

• mined leaves

• leaf deformity


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• number of moth, sawfly and beetle larvae feed on foliage, often in aggregations of several individuals; some consuming large sections or all of the leaf, others feeding on the bottom or top layers of the leaf only

• number of moth, sawfly and beetle larvae feed on the bottom or top layers of the leaf only

• larvae of several small moth species roll and/or tie leaves together and feed within protected casing

• a few species of moth larvae live in groups in nests of leaves and silk from which they feed on the foliage

• larvae of certain tiny sawfly, moth and beetle species feed between the layers of the leaves leaving them translucent

• gall-making flies, aphids, wasps and spider mites can cause swellings on the surface of the leaves and leaf petiole as a result of feeding and egg laying activity, often killing new growth

25

4 Stem

or Log

• exit holes in trunk with evidence of pitch and/or sawdust

• numerous wood boring beetles and wasp that feed both under the bark and into the heart wood of the tree

3 Twig and

Branch

larva and damage of an emerald ash borer

on maple gall caused by gauty oak gall wasp

oak twig pruner damage

• gall making aphids (adelgids), wasps and flies (midges) cause stem enlargement and/or deformity as result of feeding and chemical interactions with plant; feeding scars from plant sucking true bugs

• boring feeding within the twigs and stems by beetle or moth larvae

• twig deformity

• twig and stem death with evidence of exit holes

continued from previous

page...

2Foliage (leaves)




• curling of leaf edges

• browning or yellowing of leaves

aphid damage on poplar

leafhopper sucking damage

• caused by the feeding of aphids resulting in discoloration and structure damage to leaf edge

• damaged caused by sucking feeding of numerous hopper, true bug, aphid and spider mite species


Some control options As with softwoods in Lesson Two, these insect types impact the trees in a woodland to varying degrees. For many types, the degree of damage may be determined simply by the weather during a particular year. The added stress of a summer drought, wet spring or harsh winter can intensify the impact of a usually less harmful pest outbreak.

Some pests may be considered more of a visual problem such as galled and deformed leaves or the odd stem killed by a web spinning sawfly which can look unattractive. In forested settings, there may be no need for control options for such pests.

For defoliators, control is often necessary when populations get high enough. Knowing what products to use in a specific situation is key to protecting the resource. Chemical or biological insecticides may not be effective if the pest bores into trees, lives in a ball of spittle or mines into needles. Certain products may work very well on moth larvae, such the biological insecticide Btk, but are completely useless on wasp or beetle larvae.

New products include viruses developed specifically to target particular species, chemical mating disruptors and various lures and attractants.

Knowing what control products are available and when, how and if to apply them are key in protecting your woodland. Remember to read and follow the instructions on the label when using any control agent. Proper application and use of recommended personal protective equipment are essential for the safe use and effectiveness of any pesticide.

26

5 Root

• chew marks around root collar and overall yellowing of entire tree

root collar damage• ground dwelling beetle larvae often feed on the roots of smaller trees

Review

Taking a closer look at the damage to trees on your woodland is the first step to identifying the pest. The tree part and the type of damage are both initial clues. If you decide that a control product is needed, take time to review and select the appropriate option.

Quiz 3 1 Compared to softwoods, hardwood infestations are:

qa) More frequent

qb) Less frequent

qc) About the same frequency

2 Hardwood trees with insect damage can have:

qa) wilting leaves

qb) curled up leaves

qc) evidence of chewing

qd) any of the above

3 Tents or webbing created by insects are found on both hardwoods and softwoods.

qTrue qFalse

4 Adult beetles feed on:

qa) the stem

qb) the root

qc) the branch

qd) all of the above

2726

28

You may be fairly certain of the insect involved after consulting the field guide. However, if you are still unsure or if you want to confirm the identification you have made, you can send a sample to Nova Scotia Department of Natural Resources (NSDNR). Lesson Four covers what to do if you want to have an insect identified. This is done using a sample of the insect if available or a sample of the damage.

This lesson provides guidelines to help you collect and send the necessary information. This will ensure you receive accurate and timely feedback. Once the insect is identified, NSDNR staff can suggest some control options.

Insect is still on site

horntail Wasp in a person’s hand (for scale)

Let’s start with the easiest one. You have found an insect and used your field guide and this module to make an identification. You would like to make sure that your assessment is correct. Take the insect and a sample of the damaged tree part to your nearest district NSDNR office. A PDO will confirm identification or send it to the Forest Health group for further work. See Appendix A for contact details. They will ask you some questions about your woodland and get your contact information.

If you aren’t able to identify the insect, do not lose heart. There are approximately 30,000 different insect species in Nova Scotia. Even those who specialize in this field are stumped more often than they would like to admit.

Insect cannot be foundA more perplexing situation occurs when you see damage and are unable to find the insect that has caused it. This requires a bit more work on your part. A digital camera, notebook, pencil, and hand snips are good tools to take with you when trying to collect a damage sample.

camera, notebook, pencil and hand snips

check the damage from a distaNceFirst look at the damaged tree or trees from a distance, far enough away that you can see most of the tree(s). Make a note of the overall appearance in your notebook and any of the following:

• Thin crowns• Discoloured foliage• Damage only on one side of the tree or only on

one part of the tree• Damage on the new growth or old growth

28

leSSoN 4 A Quick Guide To Sample Collection

29

heavy defoliation of hemlock by pale wing grey

Also look at the terrain. Is the tree on a rise or in a hollow?

Take a photo that best shows what you see when you look at the whole tree.

As you walk closer to the tree(s), look for damage in the soil around the tree and also note:

• Work done around the tree(s) that might have damaged the roots

• Very wet or very dry ground • Damage from animals digging• Look at the other tree species. Are they healthy

or are they looking discoloured or thin? Do you notice any fungus growing where the tree meets the soil? Again, take photos of the soil and area surrounding the tree(s).

check the damage from close uP

balsam fir sawfly larva

Next go closer to the tree(s) and look at the damage. Estimate how much of the tree(s) is damaged. Note if the damage is limited to a couple of shoots or a larger portion of the tree. Even if you don’t see the insect, you may see some webbing or evidence of feeding. A photo would be very helpful. Try to focus the photo as clearly as possible. Use the close up or macro function if your camera has one.

Collecting samples

landowner collecting branch sample

For your best chance at identifying the insect pest(s), collect a sample of the damage. Using your hand snips, clip off a section of foliage that has both healthy and damaged parts. It’s difficult to determine the exact size of a sample. Remember that this may have to be sent to the NSDNR Forest Health group, so a truckload of foliage is a bit impractical. Do your best to get a representative sample and fill in any gaps in information with your written notes and photos.

Don’t forget to review your photos before you leave your woodland. It’s not always easy to get good shots but clear, well-lit pictures help provide needed information to assess the damage.

28

30

There are also some standard questions that NSDNR staff may ask when you bring in a sample for identification. It helps if you can answer the following:

• Where was the sample collected?• When was the sample collected?• What is the tree species?• What part is affected? For example: foliage,

shoot, last year’s growth.• Where is the affected tree(s) located? For

example: forest or woodland, yard or landscape, urban, barnyard or pasture, plantation, Christmas tree lot.

• What is the approximate size of tree(s) affected, height and diameter?

• What is the approximate age of tree(s)?• What is the degree of damage? For example: - none (you would use this if you found an

insect that was not causing any noticeable damage but you wanted to know what it was)

- trace (1-5% of leaves, needles, twigs, or branches affected)

- light (6-29% of leaves, needles, twigs, or branches affected)

- moderate (30-69% of leaves, needles, twigs, or branches affected)

- have/severe (70-100% of leaves, needles, twigs, or branches affected)

• How many trees are affected?• Any other notes or comments?• What is your contact information?

Identification Now that you have your sample, notes and pictures, you can go to your local NSDNR office. Each district office has a Pest Detection Officer who is familiar with forest pests. They may be able to identify the insect damage or they may want to send it to Forest Health for confirmation.

Once the sample reaches the Forest Health group, you can expect a response within seven business days. If a successful identification is made, you will be told what the insect is and some options to choose from to deal with the insect.

Unless there is an invasive alien species involved, the choice to control or manage the insect is up to the woodland owner. We can provide information and options so that you can manage your woodland to best meet your goals.

31

Insect present but unknown. Softwood trees. John and Marie LeBlanc, and their son Jeremy have a 20 ha woodland in Urbania, Hants Co. The family uses the woodland trails for recreation and harvest a few natural Christmas trees.

As she was walking in the woodland one August, Marie noticed one type of softwood was looking thin, almost like she could see through them. After taking a closer look, she found the branches were missing a lot of needles. She thought it was strange that the outer edge of the branch still had needles but the part closer to the tree had very few.

John and Marie were quite sure the trees were balsam fir. They checked in Module One of the Home Study series to confirm that it was.

The following year, they kept a close eye on their trees to see if the problem would continue. In June, they noticed caterpillars feeding on the needles. They knew that they could take a sample to the local DNR office for identification.

John and Marie found 20 trees with caterpillars on them. Jeremy took some pictures, collected a few caterpillars and some small branches, and put them in an ice cream container. They wrote down the information that DNR would need.

• The insect was collected in Urbania, HantsCo.• Collection date was 15 June 2012• The tree species is balsam fir• The needles are being fed on by a caterpillar• It is in our woodland• Trees are about 3 m tall• Trees are about 10 yrs old• About 30% of the tree is affected• There are 20 trees with caterpillars feeding on them

• We noticed last year in August that some of the balsam fir missing needles. Not the needles on the outside of the branch but the needles on the inside, closer to the trunk. We have not sheared the trees or done any work around them.

• Name, Address, telephone and e-mail.

woodland owners showing sample to Pest Detection Officer at local Department of Natural Resources office

Armed with their information, they headed for the Natural Resources office to speak to the Pest Detection Officer (PDO). He looked at the insect sample and thought that the caterpillars were the balsam fir sawfly.

“But,” he said, “I would like to send this sample to our Forest Health office in Shubenacadie. They will be able to confirm this and provide management options for your woodland. Once they receive it, they will respond within seven business days, so you should hear by the end of next week.”

Case Study One

32

The following week the LeBlanc’s received an e-mail from the Entomologist at Forest Health. The insect was indeed the balsam fir sawfly. They found the reason the trees looked see-through was because this insect feeds on the previous year’s growth and leaves the new needles untouched. This leaves the trees with a silhouette appearance.

The entomologist provided several options to deal with the balsam fir sawfly. He wrote, “They are almost finished feeding so most of the damage is

done. Control this year may lessen the population for next year but will not fix the damage already caused. A biological insecticide is available that may help. There are also natural predators and disease that affect balsam fir sawfly. If you’re not planning to use these trees right away, you may want to wait a year and see how the population looks then.”

John, Marie and Jeremy decided to continue to watch the population and see what happened in the following year.

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Insect not present, only damage. HardwoodsKatherine Murray purchased a woodland five years ago in western Nova Scotia. While driving in Digby County in the early fall, she noticed clumps of tent-like webbing on some of the hardwood trees along the road. She then went back to her woodland to see if there were any of these clumps in her trees.

close up of webbing

She found a mass of webbing on the outer end of an alder branch and then another one on a poplar. She noticed that some of the leaves looked like they were missing pieces. She was able to reach the web mass on the alder and pulled it down for a closer look. There were no insects inside the mass, only small dark coloured lumps and the remains of partly eaten leaves.

Concerned that this may impact her woodland, Katherine took some notes on the kind of trees that had web masses, where they were found on the trees, and how many of her trees had them. She also took a couple of pictures of the webbing she couldn’t reach. Lastly, she snipped off the web mass from the alder.

Returning home she looked in her Woodland Home Study Module and Companion Field Guide. She found out that what she was seeing was a tent made by an insect. According to the field guide, three types of insects make feeding tents in Nova Scotia. Number one was the ugly nest caterpillar which is seen much earlier in the season and only feeds on pin cherry. It wasn’t that one. Number two, the eastern tent caterpillar, is usually seen earlier in the year. Since she didn’t find any insects, she didn’t know when they were there. She also read that the eastern tent caterpillar builds its web where two branches meet (crotch) of the tree so it was probably not that either.

The last insect she looked at was the fall webworm. Its caterpillars feed in the late summer so the timing was right. They feed on the leaves of a wide variety of hardwoods – Katherine had noticed the tenting on five different kinds of trees. They make their tents on the outer part of the branches where she had originally seen them, encompassing some leaves within the mass. The book also said that the caterpillars leave the web mass to form pupa and overwinter, so that was why it was empty.

Satisfied that this was the insect that had caused the damage, Katherine did a bit more checking on the internet. She found that this insect, although unsightly, usually does not cause permanent harm to the tree. And the dark-coloured lumps that she saw in the web mass she collected—droppings from the caterpillars that had lived there.

Case Study Two

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Quiz 4 1. How many different insect species are there in Nova Scotia?

qa) 500 qb) More than 1,000 qc) More than 30,000 qd) Millions

2. What tools do you need to collect an insect sample?

qa) Hand snips, camera, notebook, pencil, container for the insect sample

qb) Axe

qc) Computer, smartphone, power saw

qd) Entomologist

3. What information do you need to have an insect identified?

qa) Date insect was collected

qb) Location insect was collected

qc) Type of tree the insect was found on

qd) All of the above and more

4. Where can you take your insect sample from your woodland for identification?

qa) NS Department of Health

qb) NS Department of Natural Resources

qc) Local library

qd) NS Department of the Environment

5. Who do you ask for when you take in your insect sample?

qa) The Pest Detection Officer (PDO)

qb) The Manager

qc) The Wildlife Specialist

qd) The Conservation Officer

Review

A conclusive ID of the insect pest affecting your trees is necessary to help you to choose the best solution. Collecting a sample and noting various features of the damage are part of this process. DNR staff can assist you with the final identification and also suggest some treatment options.

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1 Pests of the Acadian Forest COMPANION FIELD GUIDE This field guide has profiles of the most common insect pests in Nova Scotia and their host trees. Full Colour. Available from Forest Protection in Shubenacadie 902-758-2232, Extension Services 902-424-5444, or your local DNR office.

2 Nova Scotia Department of Natural Resources web site novascotia.ca/natr/forestprotection/foresthealth

Information sheets on specific insects

Insectary Notes – A reader -friendly, bimonthly newsletter. Issues back to 2005 on line. The July/August 2011 Issue has an A-Z index of past topics back to 1993 and what issue they appeared in if you want more info on a specific insect.

A list of Pest Detection Officers at the 2 DNR offices. You can also call your local office directly.

3 Natural Resources Canada - Canadian Forest Service web site www.cfs.nrcan.gc.ca

Under Topics, see “Insects and Diseases”

Info on Ecosystem Impacts and Economic Impacts.

A database on trees, insects and diseases (Under “Related Resources”).

Under CFS, see “Publications”

Free publications on a wide variety of pest topics. Enter your topic under “Search”. Order a paper copy or download a PDF depending on what is available. You can also contact the CFS Atlantic Office in Fredericton , NB. 506-452-3500

4 Tree Species Trees of Nova Scotia by Gary Saunders, Illustrated, 102 Pages, Nimbus Publishing

novascotia.ca/natr/forestry/treeid Provided interactive guide to common native trees of Nova Scotia

5 Christmas TreesDNR web site novascotia.ca/natr/forestprotection/foresthealth/christmastrees/

Description of Christmas tree pests

CFS “Publications”. See Three above. Enter “Christmas Trees” or “Balsam Fir”.

One useful booklet from CFS is Christmas Tree Insects and Diseases, A Field Guide, 2008 which also includes beneficial insects.

6 Invasive Alien Species Forest Invasive Alien Species web site www.exoticpests.gc.ca

Includes info on entry points, impacts and specific insects.

CFS web site under “Insects and Diseases” and also “Ecosystem Impacts”. See Three above.

Invasive Species Alliance of Nova Scotia www.invasivespeciesns.ca

Information on the threat of invasive alien species at the provincial level

Canadian Food Inspection Agency www.inspection.gc.ca/plant

Go to “Plant Protection” and then “Insects”. Also see Forestry

Exports and Imports for certification programs and regulations on wood products.

APPENDIX A INFoRMAtIoN SouRCeS AND ReFeReNCeS

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Gall: Plant galls are abnormal outgrowths on tree parts and can be caused by various parasites, fungi, bacteria, insects and mites.

Instar: A stage in larval development of an insect, between two moults.

Moult: When the insect sheds its outer layer during growth.

Nymph: The larval form of certain insects usually resembling the adult form but smaller and lacking fully developed wings.

Pheromone: A chemical compound, produced and secreted by an animal, that influences the behavior and development of other members of the same species.

Pupa: The non-feeding stage between the larva and adult in insects, during which the larva typically undergoes complete transformation within a protective cocoon or hardened case.

Biological Control: A method of controlling pests using other living organisms; knowledge of natural predators, parasites, and other interactions are used to manage pest populations. Biological control may be a component of Integrated Pest Management.

Btk: Bacillus thuringiensis var. kurstaki (Btk) is a type of bacteria found naturally in the soil that is known to cause illness in various insect larvae, including caterpillars of pest species such as gypsy moth, spruce budworm, and cabbage looper. It is used as a form of biological insecticide.

Cocoon: a casing spun of silk by many moth caterpillars and other insect larvae as a protective covering while in pupa stage. Cocoons may be tough or soft, opaque or translucent, solid or mesh-like, and of various colours and layers depending on the type of insect larva producing it.

Defoliator: an adult or larval insect which strips all the leaves from a tree or shrub.

Larva: a juvenile form of an organism before morphing into adult stage.

APPENDIX B gloSSARy

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APPENDIX C PHoto CReDItS

All photos are from NS DNR sources except for those noted below:

• Spruce budworm larva: Natural Resources Canada, Canadian forest Services.• Webspinning sawfly: Milan zubrik, Forest Research Institute, Slovakia.• Spittle bug on pine: Tim Tigner, Virginia Department of Forestry.

APPENDIX D eXeRCISe AND QuIz ANSWeRS

lessoN 1:1. c 2. b 3. c 4. a 5. b 6. d 7. b

lessoN 2:1. d 2. a 3. b 4. d

lessoN 3: 1. b 2. d 3. a 4. d

lessoN 4:1. c 2. a 3. d 4. b 5. a

EPrinted on paper that

contains recycled fibre.

woodland management home study module module 15: pests...

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