Caddisfly is a general term for a large order of insects with over 12,000 included species. As with most aquatic insects, the animal can appear different depending on its stage of development. The adults are similar in appearance to moths but with hairy mesh-like wings. Their bodies are generally elongated and measure around a quarter of an inch in length (.635 cm). They have small heads and long hair-like antennae. They can come in a variety of colors and patterns.
Caddisflies require clean, freshwater environments to reproduce. The larvae construct silk pouches which they attach to underwater objects to protect themselves during a long developmental period called the pupa stage. These pouches are covered with collected stones, twigs, sand and other organic debris which both camouflage and “armor” it against predators. After weeks in the pupa stage, the adult caddisfly will emerge, swim to the water’s surface and almost immediately seek a mate, thus continuing the cycle.
Once a caddisfly reaches the adult stage, its life is nearly over. Its major function during this stage is reproduction. Adults don’t even eat as their mouth-parts are vestigial (non-functional). During the larval stage, however, the insect is an omnivore and may even scavenge for food.
Caddisflies are common along streams, rivers, lakes, ponds and vernal pools all over North America. There are numerous species of this insect in Oregon, including Netspinning Caddisflies (family Hydropsychidae), Longhorned Caddisflies (family Leptoceridae) and Northern Caddisflies (family Lemnephilidae). Because they are sensitive to water-borne contaminants, their presence is used by biologists to assess the health of an aquatic environment.