148 



THE DIPTEBA-BRACHTCERA OF TASMANIA. 

 Part III. Families Asilid^, Bombylidje, Empidas, 



DOLICHOPODID^, & PHORIDJK. 



By Arthur White. 

 (Read 14tli Aug, 1916. Issued separately 30tli Nov., 1916.) 



Family VII. ASILIDiE. 



This family comprises the well-known and universally 

 distributed "JRobber Flies," so called on account of their 

 predaceous habits. The species are of medium or large 

 size, tb e head attached to the thorax by a slender neck ; 

 front excavated between the eyes, which are separated 

 in both sexes; thorax with well-developed bristles; wings 

 with the normal venatioii of the Brachyctra, posterior cells 

 five in num.ber, the three basal cells always long. 



The A><ilidce- are strongly-built predaceous flies, attack- 

 ing insects of widely differing orders. I have seen a 

 specimen of Asiliis alcetvji having as its prey a dragonfly 

 very much larger than itself. In Tasmania the sjDecies 

 are only of moderate size, but on the mainland of Australia 

 some very large species occur, one of these — Phellus glaucus 

 — being one of the largest known diptera. 



The Asilif/ce are divided into four subfamilies, which 

 are distinguished as follows : — 



1. "Marginal ceil ojoen, or if just closed then the 



radial vein sharply curved up at its end so as 

 to form a blunt end to the marginal cell." (Ver- 

 rall) 2' 



"Marginal cell closed, and with a short petiole, 

 the subcostal and radial veins meeting at an 

 almost equal curve." (Verrall) 3 



2. Alula and hind-angle of wing missing; tarsal 



claws very long ; abdomen extremely narrow and 

 greatly elongated Leptog-astpinse 



Alula and hind-angle of wing usually present; 

 tarsal claws short; abdomen not extremely nar- 

 row, and only moderately elongated. Dasypogoninse 



3. Third antennal joint with an arista. Asilinse 



Third antennal joint without either style or arista 



Laphrinse 



