HOW TO KNOW THE IMMATURE INSECTS 



25b. Penultimate abdominal segment shorter than ultimate, or if long- 

 er, then without a deep transverse depression; apical segment 

 not as above, the hairs not closely approximated 26 



26a. Thoracic segments each with 2 long hairs, one on each side on 

 ventro-lateral margin; apical segment with 6 or 8 long hairs; 

 head well developed, forwardly protruded, and more or less cone- 

 shaped when viewed from above, appearing flattened when view- 

 ed from side; penultimate segment usually shorter than ultimate 

 or not much longer; body straight in life. 



Fig. 556 Family ASILIDAE 



Around 4,000 species of the 

 robber flies have been describ- 

 ed. The larvae inhabit soil 

 with decaying organic matter 

 Fig. 556. Promochus vertebrotus Say. where they prey upon other 



insect larvae. 

 26b. Thoracic segments without hairs, if present, they are very weak; 

 apical segment without distinguishable hairs; head not mucli 

 protruded, directed downward, not cone-shaped, with a dorsal pro- 

 tuberance when viewed from side; penultimate segment distinctly 

 longer than ultimate; body usually curved in a half circle in life. 



Fig. 557 FamUy BOMBYLIIDAE 



About 1,800 species of bee 

 flies are known. The first in- 

 star larvae are slender and 

 legless with hairs on thorax 

 and anal region which disap- 

 pear in the latter instars. They 

 are predacious or parasitic on 

 the larvae of bees and wasps, 

 pupae of tsetse flies, caterpil- 

 lars and also on the eggs of 

 Fig. 557. Spomopolius ffulvus Wied. beetles and grasshoppers. Some 



Hemipenthes have been reared 

 from ichneumonid cocoons. 

 That would suggest that they 

 ore hyperparasitic. 



Key to the PUPAE of the more important families 

 of DIPTERA 



(After John R. Malloch, 1917) 

 la. Pupa not enclosed within the larval skin, if so, the head is distinct 

 as in the larva, or the puparium is slightly flattened dorso-ventral- 

 ly, its texture leathery, not sclerotized, and the anterior respiratory 

 organs not distinguishable; adult or pupa emerges through a rec- 

 tangular split on dorsum of larval skin. 

 Suborder ORTHORRHAPHA 2 



199 



