110 



GENERAL ZOOLOGY 



carnivorous and live either in or near the water. The bee- 

 flies (Bombyliidce) superficially resemble bees, having 

 spotted or banded wings and hairy bodies. They frequent 

 flowers and their long proboscis enables them to get nectar 

 and pollen. Their larvae are often parasitic on noxious 

 insects, such as caterpillars and grasshoppers, and hence are 

 beneficial to man. The robber-flies (Asilidae, Fig. 53) 

 are veritable hawks among insects. They are slender- 

 bodied creatures which fly with great agility, often captur- 

 ing insects larger than themselves on the wing. Though 





FIG. 53. Diptera, Bracyccra. Flower-fly, drone-fly and its "rat-tail" larvae, 

 robber-fly, flesh-flics and maggots on fish, horse fly with larva and eggs. 



generally beneficial, they sometimes do injury to bee- 

 keepers and are known in some parts of the country as 

 " bee-killers." The bot-flies (GEstridce) are parasitic and 

 have unique habits. The larvae live in the bodies of living 

 animals; the common one in the horse being found in the 

 stomach; those of man, the cow, and rabbit beneath the 

 skin. The tachina flies (Tachinidce) do much good by 

 destroying caterpillars and other insects. They lay their 



