464 
THE STUDY OF INSECTS. 
The larvae are parasitic, infesting hymenopterous and 
lepidopterous larvae and pupae and the egg-sacs of Orthop- 
tera. The pupae are free. 
Fig. 564.—Wing of Pantarbes capito. 
The family is a large one, including many genera and 
species. 
Family THEREVID/E (The-rev'i-dae). 
The Stiletto-flies. 
With the flies of this family the head is transverse, being 
nearly as wide as the thorax; and the abdomen is long and 
tapering, suggesting the name stiletto-flies. These flies are 
small or of medium size; they are hairy or bristly. The 
antennae are three-jointed; the third segment is simple, and 
usually bears a terminal style; but this is sometimes want¬ 
ing. Three ocelli are present. The legs are slender and 
bristly; the empodia are wanting. 
Vein III of the wings (Fig. 565) is four-branched, and 
the last branch (vein III 6 ) terminates beyond the apex of 
the wing; the branches of vein V are all separate ; cell VIII 
is closed near the border of the wing; the 2d cell III and 
cell V are long. 
The adult flies are predaceous; and conceal themselves 
among the leaves of low bushes or settle on the ground in 
sandy spots, waiting for other insects upon which they 
prey. 
The larvae are long and slender, and the body is appar¬ 
ently composed of nineteen segments. They are found in 
