Still others build and trap food with spider type webs. Some species are herbivorous others are predacious. Caddis larva come in a wide range of sizes and colors. Laval populations of many species go through predictable behavioral drift cycles where they are consumed by trout and white fish in great numbers. When the larva has reached maximum maturity it crawls into a protected niche and constructs a cocoon.
Metamorphosis starts to change the larva into an adult insect.
It develops wings, feelers, long legs and sex organs. This complicated transformation can take weeks. During this period the insect is unavailable as trout food except during catastrophic drifts caused by floods etc. When the metamorphosis is complete, the newly formed adult insect chews an exit hole in on end of the cocoon and crawls out. It is now an air breathing organism surrounded by water.