480 



DIPTERA 



as sub-families. The Xylophaginae are a small group of slender 

 Insects, perhaps most like the short-bodied kinds of Asilidae ; 

 the third joint of the antenna is vaguely segmented, and there 

 is no terminal bristle. Ehachicerus is a most anomalous 

 little fly with rather long stiff antennae of an almost nemo- 

 cerous character, the segments of which give off a short 

 thick prolongation on each side, reminding one of a two-edged 

 saw. The three or four British species of Xylophaginae 

 are forest Insects, the larvae of which live under bark, and 

 are provided with a spear-like head with which they pierce 

 other Insects. The Coenomyiinae consist of the one genus 

 Coenomyia, with two or three European and North American 

 species. They are remarkably thick-bodied, heavy flies, reminding 

 one somewhat of an imperfect Stratiomyid destitute of orna- 

 mentation. The metamorphosis of C. ferruginea has been 

 described by Beling. 1 The larva is not aquatic, but lives in 

 burrows or excavations in the earth where there are, or have 

 recently been, rotten logs ; it is probably predaceous. It is 

 cylindric, with an extremely small head and eleven other segments, 

 the stigma on the first thoracic segment distinct ; the terminal 

 segment is rather broad, and the structures surrounding the 

 stigma are complex. The pupa 

 has stigmata on each of ab- 

 dominal segments 2 to 8. Not- 

 withstanding that the fly is so 

 different to Xylophagus, the 

 larvae indicate the two forms 

 as perhaps really allied. One 

 of the Leptinae, Atherix ibis, 

 has a singular mode of ovi- 

 position (Fig. 227), the females 

 of the species deposit their eggs 

 in common, and, dying as they 

 do so, add their bodies to the 



Common maSS, which becomes FIG. 227 .Atherix ibis. A, The fly, nat. 



an agglomeration, it may be size . > B ' m f s f dea , d flies overhanging 



water, much reduced. 



of thousands of individuals, and 



of considerable size. The mass is attached to a branch of a 



bush or to a plant overhanging water, into which it ulti- 



1 Verh. Gcs. Wien, xxx. 1880, p. 343. 



