4 Orthonhapha brachycera. 



rudimentary or wanting (Leptogaster). The alar squamula is small, 

 more or less hairy at the margin; the thoracic squamula not developed 

 but the frenulum distinct and often somewhat broad towards the 

 angulus; the balteres not covered. In rest the wings lie parallel over 

 the abdomen, one covering the other, then the squamula and frenu- 

 lum generally point outwards somewhat process-like. 



The larvæ are elongated, cylindrical, finely striated longitudinally. 

 The body consists of thirteen segments including the head and when 

 the segment-like part in front of the last segment is counted. The 

 abdominal segments have sometimes transverse swellings, especially 

 below, or they have warts. The head is small, retractile, and brown, 

 chitinised. There are some bristles on the head and the last segment. 

 The mouth parts consist of a median, hook-formed labrum, knife- 

 shaped mandibles and large and broad maxillæ with a generally 

 two-jointed palpus. The mandibles and maxillæ are movable up and 

 down. There are small antennal papillæ but no eyes. The larva is 

 amphipneustic with spiracles on prothorax and on the penultimate 

 segment (or segment-like part); the spiracles are small. The pupa is 

 free; on the front side of the head across the lower part of the eyes 

 lie the antennal sheaths, directed to each side; they have a strong 

 spine at the base and are compressed with some strong downwards 

 inclined spines. At the bases of the sheaths of wings and legs there 

 are generally small spines. The abdominal segments have each a 

 girdle of spines above and a girdle of bristles below ; at the apex of 

 the body there are some spines. 



The larvæ are carnivorous; they live in the earth or in sand and 

 devour other larvæ, and they are recorded sometimes to penetrate 

 into these and eat them quite empty. Some larvæ (Laphria) are 

 found under bark and in stubs, here feeding on larvæ of bark-beetles 

 and the like. The pupæ are likewise found in the earth or under 

 bark and in stubs. 



The Asilids are middle sized to large flies — A. crahroniformis 

 being one of our largest flies — ; they are characterised by their more 

 or less long shape and the deeply excavated vertex causing the eyes 

 to be prominent above. They are all rapacious and feed on other 

 insects which they attack with great vigour, and the prey is often even 

 as large as the attacker. From the difference in the venation of the 

 wing the Asilids fall into two groups, those with an open and those 

 with a closed subcostal cell, that is Dasypogoninae and Laphrnnae- 

 Asilinae. As already noticed by Low (Ueber die eur. Raubfliegen, 

 Linn. Entom. II, 1847, 386) the wing with the open subcostal cell is a 

 less strong appliance for flight than the wing with a closed subcostal 



