Morphology of immature stages of Bittacus choui (Mecoptera: Bittacidae) with notes on its biology

Abstract

The hangingfly Bittacus choui Hua et Tan, 2007 is unique in Bittacidae for having only three instead of four larval instars. Its morphology was studied and illustrated in detail for developmental stages, including egg, larva and pupa. Ultrastructure of eggs, larval head, spiracles and prolegs are provided. The egg is spherical. A single micropyle was observed. The larva is eruciform with a pair of prominent compound eyes and a mid ocellus; the eight pairs of prolegs are unequal in length. Nine pairs of spiracles are located on the prothorax and the first eight abdominal segments respectively; the first instar larva differs from other instars in spiracle number. The somites are unusual, with rows of protuberances bearing distinct setiferous clavate setae. The anal segment terminates in a protrusile sucker. Pupae are exarate and decticous, taking the shape of the adults. The species completes one generation per year, overwintering as a mature larva. Adults emerge in the field from mid‐July to late August.

Keywords:

• Mecoptera
• Bittacus choui
• egg
• larva
• pupa
• biology

Acknowledgements

We wish to thank the staff in the Liping National Forest Park for their help in collecting and rearing the hangingflies. We also thank Dr George W. Byers, Kansas University, USA, for his valuable comments on the manuscript. The project was financially supported in part by the National Natural Science Foundation of China (grant no. 30370179) and the Compilation of the Fauna of China (2006FY120100).