Observations on the Immature Stages of Cordilura (Achaetella) deceptiva and C. (a.) varipes1

Abstract

The life cycles and immature stages of these 2 Nearctic species are similar. Eggs are laid on the developing culms of Carex spp. Larvae of C. (A.) deceptiva Malloch (Diptera : Anthomyiidae) live as miners in the culms of only Carex stricta while C. (A.) varipes (Walker) larvae have been found in the culms of 10 species of Carex Both anthomyiids overwinter as pupae in puparia which remain within the hollowed-out culm base. Adults emerge in late spring and early summer; a 2nd generation of adults appears in late summer and early fall. Morphology of larvae and life history data confirm the placement of these species within the genus Cordilura , but similarities of the immature stages and differences in adult morphology make it difficult to sustain Achaetella as a distinct subgenus in Cordilura . Details of the C. (A.) deceptiva egg chorion are given. The outer and inner surfaces of the chorion permit a plastron respiration by the developing embryo as it is subjected to wet and dry periods.