416 NATURAL HISTORY OF ARTHROPODS. 



The flies — a misnomer here — have rather short and stout legs, and are less than a 

 half-inch in length. 



Section II. — BRACHYCERA. 



This term is here used in the modified sense proposed by Brauer, to include only 

 those families that belong to the Orthorhapha. In the adult stage, as before said, the 

 division is not a sharp one; it may be charactei-ized by the antennae, consisting 

 primarily of three joints, the third one often annulate, or simple, with a style or 

 bristle, never with verticillate fringes of hair. 



The two following families are frequently spoken of as the Notacantha ; they 

 agree in having the scutellum usually with spines or tubercles on its border, the 

 third joint of the antennae annulate, and the tarsi with three pulvilli. 



In the Xtlophagid^ the costal vein encompasses the whole wing, and the tibiae 

 are spurred. The larvas of this small family, so far as are known, live in wood. 

 Coenomyia ferruginea, found in shady woods and about old trees, is the most common 

 species that we have. It is about three quarters of an inch in length, and of a deep 

 ferruginous or darker color. Species of Xylophagus are remarkable for their general 

 resemblance to certain hymenopterous insects. The family includes about sixty 

 known species. 



In the Stkatiomyid^, on the other hand, the costal vein reaches only to the 



middle of the wing, and the tibiae are not provided with spurs. The larvae live in 



water, earth, or decaying wood. Those of a species of Stratiomyia are known 



to inhabit some of the western alkaline lakes, and a European species is found in 



salt water. The transformations of S. chameleon in Europe are 



well known. The eggs are deposited by the female, in layers 



overlapping each other, on the under side of leaves of aquatic 



plants. The larvae are naked, smooth, broader in front, where 



there is a small head ; the sides of the abdominal segments are 



Tig. wa.— stratiomyia provided with hook-like foot processes. The last three are much 



chameleon. ., ., , , . , ... ... 



narrowed and elongate, the termmal one especially so, and at its 

 tip with a circlet of hairs surrounding the stigmata. When they breathe, these hairs 

 enable the larva to keep themselves at the surface, and by their means, when folded, 

 they can retain a small bubble of air and carry it with theni beneath the surface. 

 Their food consists of very small aquatic organisms. They swim about in vertical, 

 undulatory motions. The pupae are enclosed in the anterior end of the larval skin, 

 which enables them to float about freely in the water. They escape at maturity 

 through a slit in the back which has become exposed to the air. 



Other species lay their eggs on the surface of the water. The larvae of Ephip- 

 pium thoracicum are found in nests of Formica fuliginosa, those of Chrysomyia 

 polita attack the common rape plants ; both are European. Species of Beris are 

 found in moss, and Suhula and other genera in decaying wood. There are nearly nine 

 hundred species known. 



The next two families belong to a group called Tanystoma, in which the three 

 basal cells are much prolonged, the third longitudinal vein is furcate, and there are 

 five posterior cells; the marginal vein encompasses the whole wing; there are three 

 pulvilli. 



The Tabanid^ have the third joint of the antennae annulate, and never with a 

 distinct style or bristle. The proboscis of these flies, horse and cattle, or breeze flies, 



