ASILIDJE. 53 



three submarginal and five posterior cells always present; 

 first and fourth posterior cells and the anal cell open or closed. 



The family Asilidse or Kobber-flies is one of the largest and 

 best known among diptera, including nearly three thousand 

 species, distributed among about one hundred and fifty genera. 

 Many of the species are conspicuous for their large size, the 

 largest measuring nearly two inches in length, while the small- 

 est known species are seldom less than a third of an inch. 

 They are the most predaceous of all flies in their habits. The 

 greater part of them rest upon the ground, and fly up when 

 disturbed, with a quick buzzing sound to alight again a short 

 distance beyond. Some of the Laphrinae have a striking 

 resemblance to large humble bees, and are usually observed 

 resting upon foliage about the borders of forests. All their 

 food, which consists wholly of other insects, is caught upon 

 the wing; their luckless victims when once seized in their 

 strong feet are powerless to escape. Other flies and 

 Hymenoptera are usually their food, but flying beetles, es- 

 pecially the Cicindelidse are often caught and they are known 

 to seize and destroy large dragon flies. In an instance that 

 the writer observed, a female seized a pair of her OAvn species, 

 and, thrusting her proboscis into the thorax of the male, car- 

 ried them both off together. 



The larvse live chiefly in rotten wood, under bark, or in soil 

 containing decomposing vegetable matter, under leaves, etc., 

 and feed upon grubs and other larvae. The larvse are cylin- 

 drical in shape, with parchment-like skin, the abdominal seg- 

 ments sometimes girdled with rounded tubercles, or with 

 abdominal protuberances for locomotion. The pupse are free, 

 with strong booklets at the anterior end, and the abdomen is 

 provided with spiny girdles, mixed with hairs above and be- 

 low ; the last segment has two short divaricate booklets and 

 several smaller projections. 



The young larvse sometimes bore their way completely 

 within the bodies of other larvse, remaining there till their 



