Diptera 259 



Group B. Brachycera. 



The Brachycera include those Orthorrhapha in 

 which the feelers have never more than five segments 

 and usually only three. The larvae are mostly elongate, 

 fleshy maggots with small retractile head. The 

 insects included in this section may almost all be 

 known in the imaginal state from those of the sub- 

 order Cyclorrhapha (see below p. 262) by the long 

 bristle (when present) on the third (last) antennal 

 segment being situated at the tip, instead of on the 

 upper surface. (Some of the Conopids and the 

 Platypezidae among the Cyclorrhapha and certain 

 genera of the Dolichopids belonging to the present 

 group do not conform to this rule ; see the characters 

 of these three families below, pp. 261-3.) The 

 wing-neuration is usually complex, the longitudinal 

 nervures forking often, and several cross-nervules 

 being present (150, 151, 152). 



Stratiomyidae. — The StratiomyUce are a tamily of stoutly-built flies 

 often brightly coloured. The head is as broad as the thorax, and the 

 three-segmented feelers have the terminal segment distinctly ringed 

 (as if formed by the fusion of several segments) with a claw or bristle 

 at the tip. The mesoscutellum is often spinose. The moderately 

 long and slender legs are without stiff bristles or spines. The wings 

 have the costal nervure reaching only to the tip. The larvs live in 

 damp places or in water. That of Stratiomi/s is elongate and spindle- 

 shaped w^ith a small retractile head and a breathing opening at the 

 tail guarded by branched threads arranged star-wise. The pupa is 

 incomplete and remains, either buried in the earth or floating in the 

 water, within the dried larval skin, which serves as a protection. 

 The StratiomyidsE are numerous and generally distributed. 



Xylophagidae. — The XylopluigiJj: are a small family of flies 

 resembling the Stratiomyidx in the ringed third antennal segment, 

 but there is no terminal claw or bristle, and the scutellum is not 

 spined. The head is as broad as the body which is somewhat slender 

 in build. The legs have no stiff bristles, but the shins bear spines at 

 the tip. The costal nervure is continued all round the wing-margin. 

 The flies of this family suck the juices of plants and are often observed 

 to feed on the sap of trees. 



Tabanidse. — The TabanUa or Gad-fues are usually large robust 



