FLIES. 425 



Not a few species resemble Hymenoptera, both wasps and bees, to such an extent 

 that even experienced dipterologists will sometimes hesitate to handle them till they 

 are assured of their harmlessness. Such ones, in a most striking degree, are the species 

 of Ceria, which differ from other Syrphidse in having a terminal style to the elongated 

 antenna?. Not only are the thorax and abdomen covered with bright yellow markings 

 in the manner of wasps, but the abdomen is also narrowed at the base, almost petiolate. 

 Nineteen hundred species of the family are known throughout the world ; in the United 

 States we have two hundred and fifty now known. 



The species of Conops, the type of the family CONOPID.E, are often distinguishable 

 with difficulty, without a close examination, from certain species of Ceria, of which we 

 have just spoken ; they do not have, however, the false vein in the wing. The hypo- 

 pygium in this family is also symmetrical and turned under the abdomen, and the eyes 

 in both sexes are equally broadly separated. 



They are pretty flies, and are found upon flowers with the Syrphidce. The genus 

 Stylogaster, composed of four species found in Africa and America, is remarkable for 

 having the female ovipositor longer than the entire body, with the ex- 

 ception of the proboscis, which is yet longer, and provided with two 

 hinges. The larvae of members of this family are parasitic, chiefly upon 

 humble-bees and wasps, but also they have been found in the bodies 

 of locusts (CEdipodcC). The writer has observed Conops tibialis fol- 

 lowing a species of Bombus and repeatedly flying against it. It is F:G> f-^^f onops 

 probable that the eggs are thus deposited by the female upon the 

 body of the bee, and, hatching, they burrow within the abdominal cavity, and there 

 remain feeding upon the non-vital portions till they have arrived at the period for 

 their transformation, when they escape in the adult form through an opening made 

 between the abdominal rings. The family is represented so far in the United States 

 by about thirty species. 



There are but few examples among insects that offer such strange and curious facts 

 in their biological history as in the family of (ESTRID^E or Bot-flies. They are mostly 

 flies of moderately large size, more or less hairy, and inconspicuous in their coloration. 

 The antennae are small, inserted in rounded pits from which only the small bristle 

 projects ; the middle part of the face is exceedingly narrow, the opening of the mouth 

 is very small, and the oral parts rudimentary. The teguloa are very large. 



All the species yet known (about sixty) are parasitic in their larval state upon 

 vertebrate animals. The adult fly takes no nourishment, but subsists for a few weeks, 

 long enough for procreation, wholly upon the substances stored up by the larvae. 

 With a single exception the parasitism is confined to mammals, and occurs in three 

 different ways, the larvae living under the skin, in the nostrils and frontal sinuses, and 

 in the stomach. It is an interesting fact that with but few exceptions each species is 

 confined to a single animal, and each genus, or rather each group of allied species, 

 is parasitic in the same way upon similar animals. 



Seven species of Gastrophilus are found in the stomach or the intestines of the 

 horse and ass ; other species believed to be of this genus, whose transformations are 

 known, live in the stomach of the elephant and rhinoceros. 



Thirteen species of Ilypoderma are known to live in the skin of the horse, the ox, 

 the buffalo, the sheep, the goat, four species of antelope, and the musk deer. Species 

 of (Estromyia likewise infest the skin of Lagomys and Hypodceus. (Edomagena 

 tarandi is parasitic in great numbers in the skin of the reindeer in both Siberia and 



