FIELD BOOK OF INSECTS. 



Third joint of the antennae composed of 8 rings, the 

 first of which is only slightly longer than the following 

 ones. Goniops (wings dark in front, clear behind; eyes of 

 female acutely angulated above) and Pangonia (wings 

 nearly clear or else uniformly darkened; female's eyes not 

 so angulated; proboscis often very long). 

 3. Third joint of antennae with 4 rings; front of female 

 very wide. Wings darkened and spotted with rings; 

 when at rest, held in a roof -like position ..... H&matopota. 



Third joint of antennae with 5 rings and with a distinct 

 basal angle or process above (the southern Diachlorus 

 differs in not having this process); front of female not 

 unusually wide. Hind tibiag without long hairs (such as 

 the western Snowiella has) .................... Tabanus. 



'These trim-appearing flies [see Leptis, Plate LXVII, 

 and Chrysopila, Plate LXVI] have rather long legs, a 

 cone-shaped abdomen tapering towards the hind end, and 

 sometimes a downward projecting proboscis, which with 

 the form of the body and legs has suggested the name 

 snipe-flies" (Comstock). They are usually of medium 

 size for flies and are frequently found resting head-down 

 on grass stems and tree trunks. The squamae are rudi- 

 mentary; the costal vein surrounds the wing; the antennae 

 vary greatly from genus to genus but the joints beyond the 

 second are usually more or less fused. The larvae, which 

 live in decaying wood, under bark, in the burrows of wood- 

 boring insects, in moss, and even in water, are predaceous 

 as are also most of the adults. 



CYRTID^E 



These rarely noticed, small-headed flies have curious 

 habits. You may find Opsebius pterodontinus about the 

 webs of the common grass-spider, Agelena n&vis, and can 

 recognize it by the tooth-like projection on the front 

 margins of the wings. Its larvae live in the spiders and its 

 relatives have similar habits. The tables are turned; in 

 this case the fly eats the spider. 



248 



