The pupa and events leading to eclosion

Abstract

The pupal stage of the chironomid life cycle has attracted increasing attention since the beginning of the century, stimulated by comprehensive rearing programmes, predominantly by Thienemann and his students, notably Potthast and Bause. The systematic value of the pupal stage was appreciated early as an aid to species identification and, later, in providing additional or alternative characters to larva and adult in estimating phylogenetic relationships. As identification keys have become more comprehensive, pupal exuviae have been used as a simple and rapid way of obtaining ecological information on aquatic habitats, and data on autecology and geographic distribution. However, studies on pupal development, behaviour and physiology are still in their infancy and much of what is deduced is based on chance observations and circumstantial evidence. This is for the greater part due to the short duration of the instar and its rapid development, compounded by the generally opaque silk tube in which most of them live.