Abstract
Caddisflies (Trichoptera), are a group of insects with aquatic larvae and pupal stages, whereas adults are terrestrial insects. The aquatic larvae are found in a wide variety of habitats such as streams, rivers, lakes, ponds, spring seeps and temporary waters (vernal pools).
The larvae of many species use silk to make protective cases, which are often strengthened with gravel, sand, twigs, bitten-off pieces of plants, bark, sticks, seeds, mollusk shells or other debris. The larval case is a tubular structure and is started soon after the egg hatches.
The various reinforcements mentioned may be incorporated into its structure, the nature of the materials and design depending on the larva's genetic makeup; this means that caddisfly larvae can be recognized by their cases down to the family, and even genus level. As the larva grows, more material is added at the front, and the larva can turn round in the tube and trim the rear end so that it does not drag along the substrate.
Caddisfly cases are open at both ends, the larvae drawing oxygenated water through the posterior end, over their gills, and pumping it out of the wider, anterior end. The larvae move around inside the tubes and this helps maintain the water current; the lower the oxygen content of the water, the more active the larvae need to be.
The larvae exhibit various feeding strategies, with different species being predators, leaf shredders, algal grazers, or collectors of particles from the water column and benthos. In this contribution, some observations and experiments in school aquaria are presented.