355 



with seven pairs of lateral spiracles ; segments armed with transverse 

 series of slender bristles which become progressively stronger from 

 base to apex of abdomen. 



Imago. — See descriptions under families, and synopsis in key to 

 imagines of Brachycera. 



Family TABANIDAB 



FAMILY CHARACTERS 



Larva. — Head small, retractile, the parts as in Figure i, Plate 

 LII. Body circular in transverse section, elongate, tapering at both 

 ends, and with encircling locomotor swellings at the segmental 

 sutures in all genera except Goniops. In the latter the cephalic and 

 thoracic segments are very much tapered and considerably longer 

 than the abdominal segments ; the abdomen is stout and obtusely 

 rounded apically, the locomotor swellings being on the anterior third 

 of each of the well-differentiated segments. The posterior respiratory 

 organs are close together and situated in a vertical cleft. 



Pupa. — Head without projecting thorns. Thoracic respiratory 

 organs sessile, connected subcutaneously with a large cavity on each 

 side of median line close to anterior margin of prothorax (PI. LII, 

 Figs. 2, 3). Wings and legs rather short. Abdominal armature con- 

 sisting of 1, or 2 closely contiguous, series of bristles on each dorsal 

 segment except first, and a weaker transverse series on ventral seg- 

 ments ; apical segment ending in 6 stout processes which are more or 

 less radiate and pointed (PI. LI, Figs. 4, 5). 



Imago. — Distinguished from other Brachycera by the peculiar 

 shape of the third antennal joint, the chitinized portions of proboscis, 

 very robust body, and the wing venation. 



HABITS OF LARVAE 



Aquatic or semiaquatic, found rarely among decaying leaves or in 

 low and somewhat marshy spots in fields. As far as known, the larvae 

 are predaceous, the food of the species occurring in rivers being most- 

 ly tipulid and other larvae which burrow in the soft banks of the 

 rivers or occur in the river bottom or in drift. 



Some species are kept in check by the destruction of their eggs 

 by hymenopterous parasites. 



HABITS OF IMAGINES 



The adults of this family are familiarly known as gadflies, 

 horseflies, clegs, breeze-flies, etc. They rank with the worst of the 



