415 



Family Tachinidse — The Tachinids 



Zenillia species. 



Small to rather large flies, the thorax with bristles, the head and 

 abdomen generally with bristles. 



Head variable in size, sometimes narrower than the thorax, at other 

 times eonspicuously wider; both sexes dichoptic although the eyes of the 

 males are sometimes closely approximated, rarely so in the females; 

 front often wide in both sexes, usually wider in the female than in the 

 male of the same species; frontal bristles almost always present, orbital 

 bristles usually present in the females and often in the males; ocellars 

 present or absent; outer verticals ])resent or not distinguishable from 

 the postoeular cilia; cheeks variable in width; oral margin variable, 

 sometimes strongly produced, at other times receding; oral vibrissa? 

 usually present; proboscis variable in length and thickness, sometimes 

 very elongate, on the other extreme very small; palpi present or absent; 

 antenna? variable, consisting of three segments, the second with a longi- 

 tudinal seam above on the outer side and usually bearing stout hairs 

 and one or more ])ristles; arista composed of two or three obvious seg- 

 ments, plumose, pubescent or bare. Thorax with bristles; hypopleural 

 bristles present, rarely weak, postscutellum well developed. Legs 

 variable, bearing bristles; pul villi always present on at least the, pos- 

 terior four legs, often elongate. Wings variable in shape, sometimes 

 pictured; all the veins simple; apical crossvein usually present, formed 



