Abstract
The peritrophic membrane (PM) in Trichoptera larvae was examined by light, scanning and transmission electron microscopy. The gut of most insects produces 2 fundamental types of PM: Type I is synthesized and secreted by the entire midgut epithelium in response to the ingestion of food; type II is synthesized by specialized cells of the cardiac valve located in the anterior midgut independent from food ingestion. Corallini (2003) described, in the midgut of Limnephilidae larvae, a type I PM which is also secreted by unfed larvae. In this study, both types of PM were observed. Type I PM was evident in larvae of Rhyacophilidae, Leptoceridae, Sericostomatidae and Odontoceridae; the type II PM was observed in larvae of Philopotamidae, Polycentropodidae and Hydropsychidae.