What happens when a caddisfly larva is ready to pupate?

When a caddisfly larva is ready to pupate, it first attaches its case to a solid object. It then seals both ends of the case for protection, leaving only small holes to allow for water circulation. The larva undergoes pupation within this modified larval case, which effectively serves as a cocoon, or it may construct a separate, specialized cocoon for this stage.1

After approximately two to three weeks, the pupa uses its mandibles to bite its way out of the cocoon. Once free, it swims or crawls to the water's surface using its hair-fringed middle pair of legs to complete its transition into an adult caddisfly.1