Gypsy MothLymantria dispar

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Gypsy moth is a non-native insect pest that defoliates forest, ornamental, and orchard trees. Its preferred hosts include, but are not limited to: oak, basswood, willow, maple, birch, and poplar. High populations of larvae affect the aesthetic and recreational value of an infested area. Most healthy trees can withstand a single year of moderate-to-severe defoliation, but two-to-three years of heavy defoliation can result in branch or whole tree mortality.

TreeAzin® Efficacy and Treatment Timing OptionsTreeAzin controls gypsy moth populations by inhibiting larval development, therefore, decreasing the amount of foliage consumed by the pest. Treatments can be done in the fall or spring to control gypsy moth populations.

Fall TreatmentsFall treatments can be made in September, October or November at a dose rate of 8 mL/inch DBH on trees up to 30 inches DBH. BioForest’s efficacy trial in Massachusetts in 2016 indicated that injections done in all fall months resulted in significant TreeAzin residues in leaf samples collected in the spring of 2017 (Figure 1). BioForest recommends treating in November to ensure the highest concentrations of TreeAzin are available in leaves the following spring.

Red and white oak trees were used in BioForest’s fall treatment trial and were able to uptake product even after the leaves had fallen in November. Transpiration rates can be high in September and tend to slow down in October when leaves are senescing, which may slow product uptake. Not all tree species may uptake product effectively in November without leaves. When treating trees other than oak in late fall, BioForest recommends consulting a Technical Specialist before application.

Post-Treatment Leaf Residue Assessment Following Fall Injections

September October November

Tree

Azin

(mg/

kg) p

rese

nt in

oak

leav

es

6.0

8.0

10.0

12.0

2.0

0.0

4.0

Figure 1: TreeAzin residues present in foliage collected in May 2017 following fall treatments in 2016. The red line shows the minimum concentration of TreeAzin required to kill gypsy moth larvae.

NEW: FALL GYPSY MOTH TREATMENTS

Post-Treatment Defoliation Assessment

Non-Treated

% Tr

ee D

efol

iatio

n

Treated

10.0%

15.0%

20.0%

25.0%

0.0%

5.0%

About BioForestEstablished in 1996, BioForest specializes in innovative product development, and consulting strategies for urban and commercial forest protection. In 2015, BioForest became a subsidiary of Lallemand Plant Care to oversee and develop its Forestry division. BioForest is a Canadian company based in Sault Ste. Marie, Ontario, Canada with a presence in Southern Ontario; Michigan; Missouri; Massachusetts; and Finland. BioForest’s experienced and knowledgeable staff work with clients to create and implement effective pest management and forest health strategies for urban forests, commercial forests, woodlots, cottage properties, municipalities and more.

BioForest is the registrant of TreeAzin®, a systemic insecticide that provides protection against emerald ash borer and other insect pests in the United States. TreeAzin was developed for treating threatened trees in urban forests and environmentally sensitive areas. BioForest also developed an industry leading microinjection system, the EcoJect® System, used to apply TreeAzin into high value trees. BioForest is the exclusive North American distributor of Rotstop® C, a biological fungicide used to prevent the introduction and spread of Heterobasidion Root Disease (root rot) in conifer trees.

BioForest’s purpose is to save trees from invasive pests and disease while having minimal impact on the surrounding environment. Using a science based approach, BioForest is committed to implementing effective pest management and forest health strategies.

Adult female laying an egg mass Gypsy moth larvae Gypsy moth egg mass

info@bioforest.ca · 1.888.236.7378 · www.BioForest.ca

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Spring TreatmentsSpring treatments should be made during or just after egg hatch to target first and second instar larvae to inhibit their development, and should be applied at a dose rate of 8 mL/inch DBH. BioForest’s efficacy trial in Wisconsin in May 2004 showed that trees treated with TreeAzin had lower average defoliation rates (6.8%) compared to non-treated trees that had higher defoliation rates (22.0%) (Figure 2.) Refer to BioForest’s BioSIM maps at www.BioForest.ca as a guide for when to start spring treatments.

For both spring and fall treatments, apply TreeAzin once per season and monitor gypsy moth populations annually, as needed.

Life CycleGypsy moths have one generation per year and overwinter as partially developed larvae in eggs. The eggs hatch in the spring and the young larvae, 3-5 mm in length, begin feeding on foliage. As the larvae develop, they feed on the edge of leaves throughout the spring and summer. Male larvae go through five instars (growth stages) while the female larvae have six instars. Full-grown larvae are hairy and range in length from 35-90 mm. They have pairs of five blue and six red spots along their backs. Feeding is normally completed by early to mid-July. Sixth instar female larvae are the most ravenous feeders and are often twice the size of full-grown male larvae.

Pupation occurs early to mid-summer in a cocoon in many places including trees, rocks, houses, boats, fences, and firewood. In 13 to 17 days, the moths emerge and mating occurs. Both sexes have wings, but only the males can fly. The male moth is dark brown to beige and the female moth is mostly white. The female lays eggs that are covered with fine brown hairs from her abdomen in masses of 100 to 1000 eggs on tree trunks, branches, houses, fences, and under rocks and forest debris. The adult moths die shortly after mating and egg laying.

Figure 2: Defoliation on TreeAzin treated vs. non-treated trees. Treatments were done in May and post-treatment defoliation surveys were done in July.