The Two-winged Flies 



331 



well-defended insects, as bumble-bees, dragon-flies, and the fierce and 

 active tiger-beetles. The robber-flies usually rest on the ground or on low 



Fig. 462. Fig. 463. 



Fig. 462. — ."V robber-fly, Stenopogon inquinatus. (Natural size.) 

 Fig. 463. — \ bumble-bee-like robber-fly, Dusytlis soceala. (Natural size.) 



foliage, and fly quickly up with a buzzing sound when disturbed or attracted 

 by prey. All the prey is caught on the wing, held in the long spiny feet of 

 the robber-fly, and torn and sucked dry by the sharp piercing-beak. 



Fig. 464. — Diagram of wing of robber-fly, Erax cinerascens, showing venation. 



The larvae live chiefly in decaying wood or in soil containing decom- 

 posing vegetable matter, and are also predatory, feeding on grubs and other 



Fig. 465. — Mouth-parts of robber-fly, Erax cinerascens. It., labium; hyp., hypopharynx; 

 lb., labrum; mx., maxilla; mxl., maxillary lobe; mxp., maxillary palpus. 



underground or wood-boring insects. The pupa:- are curiously spiny, the 

 spines being used as a sort of pushing or pulling organ when they get ready 

 to come to the surface of the ground or dead tree to change into imagines. 



Some of the species of the genera Laphria and Dasyllis (Fig. 463) look 

 astonishingly like bumble-bees and wasps, probably a case of protective 



