The biology and early stages of Acampsis alternipes (Nees), with comments on the relationships of the Sigalphinae (Hymenoptera : Braconidae)

Details of the biology of the braconid subfamily Sigalphinae, based on rear ings of Acampsis alternipes (Nees), are provided for the first time. A. alt ernipes is a solitary, koinobiont larval endoparasitoid of the geometrid mo th Alsophila Hubner, though there is an external feeding phase prior to spi nning a cocoon and pupation. Two features are of potential phylogenetic sig nificance indicating a close relationship with the subfamily Agathidinae: ( 1) eggs are deposited in the host's nerve ganglia, and (2) the first instar larva is polypodiform. A. alternipes completes development in the autumn a nd overwinters as a fully eclosed adult within its cocoon, enabling it to e merge and search for hosts early in spring. The posterior of the eclosed ad ult within the cocoon is immersed in a viscous liquid that also surrounds t he meconium. Chemical analysis of this liquid revealed that it comprises at least 25% glycerol and a further 25% consists of various Fatty acid deriva tives. Oviposition and developmental stages are illustrated. The overwinter ing behaviour of the agathidine braconid Earinus elator (Fabricius) is desc ribed and compared.