Case-building caddisfly larvae use the silk to construct various portable shelters. They protect soft abdomen from predators and abrasion from coarse particles drifting in stream. If disturbed, larva can retreat into the case, which is constantly being repaired when damaged, or rebuilt as the larva grows.

Do all caddisflies make cases?

Caddisfly larvae are most diverse in cool, flowing water, but have invaded a wide range of habitats. They are known to construct cases out of silk and various other materials, for shelter. ... Larvae can construct cases out of silk woven with sand grains, fragments of wood, and other materials from their surroundings.

Why do caddisflies make cases?

Caddisflies build cases that function as protective armor against predators out of a variety of materials in their environment. The results of our study demonstrate that the presence of any case, constructed from even relatively weak materials, provides protection from at least some predators.