However, with time occasionally comes wisdom, and as I began to specialize in aquatic entomology (and do a lot of catch-up learning about butterflies and moths), I gained a better appreciation of this truly remarkable group of insects. Adult caddisflies are mostly dull-colored, with a passing resemblance to drab moths, but larvae are much more creatively attired. Like their caterpillar relatives, caddisfly larvae make silk, extruding it from a gland that opens at the base of the mouth. Some use silk to weave underwater shelters that double as fishing nets for organic debris, while others tie together bits of sand, gravel, leaves, fir needles, bark, or twigs to make intricate portable cases. This architectural adaptation is at the root of the name caddisfly: “cadas” is an Old French word meaning “floss silk” and “cadice” is a Middle English word for a strip of cloth, and itinerant cloth-sellers would pin bright “cadices” to themselves to advertise their wares from afar.
So the next time you find yourself near a stream, pick up a few rocks, turn them over, and wait for some of the stony or twig-like adhesions to poke out a little caterpillar-like head and crawl around—and you too may be drawn further into the beguiling world of caddisflies.