FLIES. 



421 



FIG. 528. Anthrax semiatra, with pupa. 



it is found in a little space below a number of empty cases as though it had feasted off 

 the contents of several nests" (Jtilet/). Callostoma fuscipennis has been observed to 

 feed upon the egg-sacs of Caloptenus italiciis in 

 the Dardanelles. 



Species of Anthrax often have the wings in 

 large part dark brown, and will be observed flying 

 about on the sandy ground, and resting on sticks, 

 leaves, stones, etc. 



The species of the small family THERE VID^E- 

 numbering about two hundred known forms will be distinguished from the Asilida3 

 by their having the under lip not horny but fleshy. The short antenna have a terminal 

 style of variable form, sometimes wanting. The larva? are very slender, snake-like in 

 form, showing apparently nineteen segments beside the head, which is due to a seeming- 

 division of the anterior ones. Their antennae are very small and short. They live in 

 the earth and decaying wood, either carnivorous or feeding upon vegetable substances. 

 The larvae of a European species is said to be parasitic upon the pupae of Aleucis and 

 Sphinx. The pupae in front have spines as in the Asilidae. Most of the flies are of 

 moderate size, and, although carnivorous, are far less active than the Asilidae. The legs 

 are less stout, and in many are easily broken off when captured. Their food is chiefly 



other Diptera, for which they lie in 



f Y$ wa ^ u P on l eaves anc l bushes, and 



sometimes on the ground. 



iScenopinus fenestralis^ which be- 

 longs to a distinct family, the SCEN- 

 OPINID^E, may be noticed here. It will 

 be recognized by the accompanying 

 figure. It is common to both Europe 

 and America, and derives its specific 

 name from its prevalence at times on 

 the windows of dwellings. The very 

 slender larvaa are not infrequently 

 found under carpets and in furniture, 



but, so far from being injurious, they evidently feed upon the destructive Psocida? 



and Tineidae. 



The ACROCERID^E or CYRTID^E are a small family of curious flies, often remarkable 



for their small, one might almost say minute, head, composed chiefly of the eyes. The 



thorax and abdomen are much inflated, the tegulae are exceed- 

 ingly large and arched, the terminal joint of the antennas is 



simple, the tibiae are without spurs, and there are three pulvilli. 



The wings are very variable in neuration, sometimes simple, 



sometimes intricate. The larva? are apparently chiefly parasitic, 



and in the few species in which they have been observed are 



parasitic on spiders or their cocoons, in the former cases the 



young larvaa living within the abdomen. Several species of the 



genus Eulonchus are found in the Western States, rather more 



than half an inch in length, and with a yet longer proboscis, 



with which they are enabled to feed upon the juices of flowers. These species are 



of a brilliant steel-blue color, but usually they are smaller, obscurely colored, with 



FIG. 529. Scenopinus fenestralis, a, larva; carpet worm, 

 enlarged. 



. 530. Lasin klettii. 

 enlarged. 



