30 



BULLETIN 67, UNITED STATES NATIONAL MUSEUM. 



Fig. 59.— A robber-fly, Erax bas- 

 tardii: a, Perfect insect; 6, pupa; 



LARVA SHOWN AT SIDE. 



and the legs are usually nearly smooth. The soldier-flies (Stratio- 

 myiidae), which have many markings on the body, the horseflies 

 (Tabanida?) (fig. 143), which annoy cattle as well as man, and the 

 snipe-flies (Leptidae), with slender, tapering bodies, belong to this 

 group. Their larvae are often aquatic, or live in moist situations. 

 (b) The Tromoptera, or hovering flies, in which the empodium is 



bristle-like, much more slender than the 

 pulvilli, or else absent. The third joint 

 of the antennae does not show any annu- 

 lations. The legs usually have only fine 

 hairs, and the body, especially the thorax, 

 is often very hairy. The bee-flies (Bom- 

 byliidse) (fig. 58), with pretty pictured 

 wings, are in this group. Their larvae are 

 often predaceous or parasitic, (c) The 

 Ernegopoda, which have strong, bristly 

 legs, and often large bristles on the thorax. 

 The empodium is slender or absent, and 

 the} 7 are nearly all predaceous flies. The 

 Asilida?, or robber-flies (fig. 59), are the largest of these insects, while 

 the Empididae and Dolichopodidae embrace a host of smaller forms. 



(2) The AscMza have the antennae composed of three joints, with 

 a tiny hair or arista near the tip. The head has no distinct lunule or 

 arched suture near the base of the antennae. The pupae are coarctate. 

 This includes the large family 



Syrpnidae (fig. 156), many of 

 which are brightly and pret- 

 tily colored, and the thick- 

 headed flies or Conopidae, 

 which have the abdomen nar- 

 rowed at base. Many of the 

 larvae of the Syrphids are 

 predaceous and feed on plant- 

 lice ; others occur in mud, in 

 foul water, in ants' and wasps' 

 nests, and in bulbs of plants. 

 The larvae of Conops are para- 

 sitic in wasps and bees. 



(3) The Scliizoplwra have 

 the pupa coarctate, the larvae 

 have no distinct head, and the antenna of the fly is of three joints 

 and an arista, and the head shows a frontal lunule or arched suture 

 near the base of the antennae. This section includes two groups, 

 one in which there is only one membranous piece or "calypter" each 

 side above the haltere, the Acalypterae; and the other group in which 



Fig 



-One of the Trypetid flies, Trypeta 



^QUALIS. 



