CHAPTER VIII 



Order Diptera (continued): The Brachycera 



In the Brachycerous Flies the antennae usually consist of 



3 dissimilar segments of which the third is often elongate, 



is sometimes composed of several indistinctly-separated and 



not-independently-movable subsegments, and sometimes 



carries a terminal or subterminal, rarely dorsal, arista, or 



a terminal style. Sometimes the antennae consist of 4 or 5 



segments, and in certain species of one family {Leptidct) 



the segments are very numerous. The maxillary palps' are 



usually composed of i or 2 segments and are stifHy extended. 



The venation of the wings is often complex ; the 2nd 



longitudinal vein is not forked, but the 3rd and 4th often are. 



This section embraces fifteen families of flies, in one 



of which — the large family TabanidcB, or Gadflies — the 



females habitually suck blood, while in another — the 



Leptid(B — there are a few blood-sucking species, and in 



a third — the Asilidcs, or Robber-flies — certain species have 



occasionally been reported as attacking man. 



On the other hand the species of several large families 

 are habitually predaceous on other insects, some of them 

 being largely or exclusively predaceous on other flies, and so 

 are to be regarded as probable or possible benefactors of man. 

 In the following synopsis the families which affect man 

 in any way, for good or ill, are printed in capitals and will 

 be considered in the sequel : — 



Synopsis of the Families of Brachycera. 

 I. The 3rd antennal segment is composed of a series of indistinctly- 

 separated subsegments ; the empodia are pulviHiform ; the 3rd and 

 4th longitudmal veins are forked :— 



{a) The costal vein extends all round the wing ; squamae large ; the 

 3rd antennal segment never has a style or arista Tabanid^.. 



