Caddis flies
May 13, 2001

Caddis fly adults and larvae make up the better part of the diet of many sport fish, including brook trout. They are favorite models for fishermen who tie dry flies to imitate the adults and wet flies to imitate the larvae. They can be found in a variety of fresh water habitats from streams to stagnant ponds.

During the next few weeks, students attending the Woodland Dunes Nature Center 3rd grade Amphibmeander program will have an opportunity to observe the interesting case-bearing larvae.

To share a similar project with one's own family, locate a fresh water pool (even a puddle or a water-filled ditch.) Search the bottom for a bit of rubbish that moves. A quick dip with a jar on a string can capture the tiny creatures that have made themselves cases of leaves, twigs, sand..even tiny stones (depending on the species.) The inhabitant of the case may stick out its head, followed by some of its body and six legs. Who are they? They are part of the life cycle of an insect valuable to a wet habitat. as they provide food for fish and other aquatic wildlife.

Adult caddis flies are sort of dull-brownish, moth-like insects about 3/4 inches long, with a two inch wingspan. They have long antennae which they wave around constantly. They are night-flyers and often congregate in numbers around lights. After mating the females lay eggs surrounded by a jelly-like mass,dropping them into fresh water or attaching them to vegetation which hangs over the water. Adults may live from only a few days to a month or more depending on the species. Larval forms may take a year to mature.

So, the tiny larvae, freshly hatched need protection from the creatures that prey upon them. From a silk gland located under its lower lip the young caddis worm spins a tough silk case and then proceeds to make an outer case of various materials, which they cement in place with their saliva.

To observe how they construct a case, remove a few pieces from an active caddis worm, gently. Put it in a glass container with a small amount of water. Add some bits of colorful flower petals. In a few hours the little builder will have incorporated them around the doorway of its snug abode. Do not try to remove the worm from its hideaway as they have fastened themselves tightly with hooks at the rear segment.

When ready to pupate, the larvae shut the openings by spinning a web over them or fastening a piece of the case across the entrance. Adults emerge, but live a short life.

Observing a caddis worm pulse through water, its tiny legs and head extended from its case, is a fascinating experience. They are worth looking for. Capture a few and then return them to some natural pool. This can be a family educational activity that won't upset nature's balance.