aquatic bug puzzles - classroom study our streams

8/8/2019 Aquatic Bug Puzzles - Classroom Study Our Streams

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Dragonfly Larva

Photo credit: McCafferty, W.P.,Aquatic Entomology,1998. www.jbpub.com



Dragonfly Larva

At first glance, you might not guess that the Dragonfly

larva is a fierce underwater predator.A close look at its mouthparts will reveal the Dragonflylarva’s secret weapon. Its hydraulic lower lip can flip outand extend almost three times the length of its head tosnatch passing prey in an instant!

The Dragonfly larva breathes by taking water inthrough its rear end over gills located at the end of its

abdomen. To swim, the Dragonfly larva blasts the waterback out its rear end, making it shoot through the waterlike a jet!

* 650 species of Odonata in N. America* 10-60 mm long, depending on species

* favourite food: other insects or minnows* lives on stream bottoms, ponds or lakes* fairly tolerant of pollution



Caddisfly Larva




Caddisfly Larva

To protect themselves from predators, most Caddisfly

larvae will build a house-like case around their bodies.They gather small plant pieces, pebbles or otherconstruction materials for their tiny underwater house.The Caddisfly larva then glues the tiny bits together withsilk threads created by its own sticky spit! There arealso Caddisfly larvae found only in streams that areknown as “net-spinners”. These species use a silk net

to capture food carried by the water!Each Caddisfly larva species has its own favouritefood. Some larvae eat algae that they scrape offunderwater rocks, whereas others are predators.

* 1300+ species of Trichoptera in N. America* 2-40+ mm long depending on species* favourite food: algae, rotting plant & animal matter,

other insects* most freshwater habitat* low tolerance for pollution



Fishfly Larva




Fishfly Larva

The larvae of the Fishfly are fierce underwater hunters.Their well-developed mouthparts allow them to grab andswallow up other aquatic larvae. In fact, they are suchaggressive feeders that they will even eat other Fishflies.

Fishflies are strong swimmers that can movebackwards and forwards in their search for food. Otheraquatic insects, such as black fly and caddisfly larvae,

don’t have much of a chance when a Fishfly is on thehunt. No wonder the Fishfly, one of the largest aquaticlarvae, makes a tasty snack for hungry fish.

* 50 species of Megaloptera in N. America* 10-90+ mm long, depending on species* favourite food: other insects, molluscs & worms

* streams, rivers & lakes with soft bottoms* low tolerance for pollution



Stonefly Larva




Stonefly Larva

The Stonefly larva is a true superstar when it comes tocrawling along the bottom of a river or stream in movingcurrent! Its strong, robust legs are each equipped withtwo, tiny claws that help it cling to stones, so it does notget swept away. The somewhat flattened body of theStonefly larva allows it to explore under rocks in searchof food. Some Stonefly larvae eat algae and decaying

material found on the stream bottom, whereas othersare predators.

Stoneflies need streams that are clear, cool andhigh in oxygen to survive. So if you find a stoneflyunder a rock in a stream, chances are very good thatthe stream is unpolluted.

* 500 species of Plecoptera in N. America* 5mm-6cm long, depending on species* favourite food: bacteria & fungi, some species are

predators* among stones in fast streams & rivers

* low tolerance for pollution



Water Boatman




Water Boatman

Water Boatmen are abundant in calm lakes and ponds,or in pools on streams. These superb swimmers usetheir hairy back legs as oars.

When the Water Boatman gets hungry, it will gatheran air bubble on its belly. The Water Boatman will usethe oxygen from this bubble when it dives underwaterto eat bits of plant tissue and other stuff that has

settled on the mucky bottom. Some Water Boatmenwill feed on mosquito larvae and other small insects.

The Water Boatmen will call out to each other byrubbing their forelegs over their head to make a sound.

* 130 species of Corixidae in N. America* 3- 10mm long, depending on species

* favourite food: organic debris, some eat smallinsects



Mayfly Larva




Mayfly Larva

In order to survive, the Mayfly larva needs to find plentyof oxygen in the water where it lives. It gathers theoxygen using gills that line both sides of its body. Ifthere is too much pollution, the Mayfly larva’s gills willnot get enough oxygen, and it will die. If there are manyMayfly larvae in a stream, the water is probably healthy.If they are missing, we might need to worry about

pollution! Insects that decrease or increase in responseto pollution are often called “indicator organisms”because their presence can “indicate” altered conditionsin an environment.

* 600+ species of Ephemeroptera in N. America* 3- 20mm long, depending on species

* favourite food: algae & small bits of rotting stuff,some eat other insects* clings to rocks, or in soft soil on stream bottom* low tolerance for pollution



Whirligig Beetle




Whirligig BeetleThe Whirligig Beetle has many intriguing adaptationsfor surviving on, and in its watery habitat. It is aspeedy swimmer, spending most of its time on thewater’s surface searching for unsuspecting prey.Using its oar-like hind legs, the Whirligig Beetle zips

back and forth, and spins around in quick circles.Each of its eyes is split into two halves. The tophalf of the eye looks up at the sky for potentialpredators. At the same time, the bottom half of the eyeworks like a swim goggle, examining whatever is underthe water! When the Whirligig Beetle dives, it traps anair bubble under its wing, so that it can breathebeneath the surface.

* 50+ species of Gyrinidae in N. America* adult 3-15mm, larvae 30mm* favourite food: other insects, scavengers* adults found on surface of quiet waters* fairly tolerant of pollution



Mosquito Larva




Mosquito LarvaWe are all quite familiar with adult Mosquitoes buzzingaround our heads during the spring and summer, bitingus and making us itchy. It is only the females who feedon our blood to produce their eggs.

Mosquito larvae live in standing water, and look quitedifferent from their adult parents. They are often hairy,

wiggle, and hang upside-down from the surface of thewater. Being upside-down is great for capturing tinymicroscopic prey, which are filtered out of the water withspecial mouth brushes. The tube-shaped tails thatanchor the Mosquito larvae to the surface are actuallyused to gather air for breathing. Imagine having asnorkel on your rear end! Weird!

* 150+ species of Culicidae in N. America* 3- 15mm long depending on species* favourite food: organic debris suspended from water

surface



Black Fly Larva




Black Fly Larva

Although small, the Black Fly larva is extremely well -designed for life in running water. To anchor itself inone place, the Black Fly larva makes a little pad of silkyspit on a rock or other secure surface in the current.Shaped like a tiny punching bag (wide at the bottom,skinnier at the top), the Black Fly larva attaches its buttto the silken pad with Velcro-like hooks. After it is

securely stuck, many species of Black Fly larvae usetwo large, hairy fans (modified mouthparts) to filter foodfrom the current. Black Fly species without a fan willgraze on the organic stuff around their attachment point.

* 260+ species of Simuliidae in N. America

* 3- 15mm long, depending on species* favourite food: organic debris* attaches to rocks or other secure places* medium tolerance for pollution



Damselfly Larva




Damselfly Larva

Don’t be fooled by the Damselfly larva’s delicate

appearance. This little, slender-bodied beauty is actuallya well-adapted predator! The large bulging eyes on theDamselfly larva’s hammer-shaped head enable it to locatesmall prey as they swim by. Once the prey has beenspotted, the Damselfly larva shoots out its specializedbottom lip to catch the victim. After the prey has beenseized, the Damselfly larva folds its lip back towards its

mouth to dine on its new meal.If you look closely at the rear end of a Damselflylarva, you will see three leafy-looking tails. These “tails”work like gills, enabling the Damselfly larva to take oxygenfrom the water so it can breathe.

* 650 species of Odonata in N. America

* 10-60 mm long, depending on species* favourite food: other insects or minnows* lives on stream bottoms, ponds or lakes* fairly tolerant of pollution

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