Types of Caddisflies
There are more than 900 species of caddisflies in North America. Scientists have grouped them in 17 families. The 17 families can be sorted into several groups based on various physical differences.
Some of the characteristics that scientists look at to make the assortment are very plain to see. Others are hard to see without a microscope.
When they sort caddisflies, scientists examine the hairs on the wings. Some have “clubbed” hairs and some do not. Scientists also examine the legs of caddisflies. Some have spurs on the tibia. Others have a row of black spines on the tibia. Still other caddisflies have tiny grooves on their mouthparts
It is sometimes easier to sort caddisflies according to the way the larvae behave. The larvae develop in streams and breathe with gills. Some change environments as they develop. Some larvae in the family Brachycentridae stay near the shore when they are newly hatched. As they develop, they move out into the middle of the stream.
Many caddisfly larvae are known as “free-living” or “free-swimming”. These larvae swim or walk around in the water. They are usually predators. They feed on minnows, tadpoles, and other small aquatic animals.
Many larvae make nets to catch their prey. Some in the family Psychomyiidae make trumpet-shaped nets that they anchor on stones. Others in the family Hydropsychidae make cup-shaped nets. They point the opening upstream and then the larvae wait in a separate retreat nearby.
Many caddisfly larvae make shelter cases. They live inside the case and hide in it to escape predators. Some members of the family Calamoceratidae simply dig up hollow twigs from the bottom of the stream and use them as shelters. Larvae of many caddisfly species make a cylindrical silk case and camouflage it with grains of sand.
Some species make distinctive shelter cases. Some species in the family Lepidostomatidae make tubes that are square in cross-section. The snail-case caddisflies in the family Helicopsychidae make cases that look like snail shells.
Some larvae in the family Hydroptilidae wait to make their case until they are almost fully developed. They make a purse-shaped case that is open on both sides.
After they have finished developing, the larvae seal themselves in cases and change into adult caddisflies. After changing, the adults emerge from the water. They fly around the stream to find a mate and start the life cycle over again.