ZOOLOGY 



Fig. 85. — Robber- 

 fl\-. Nat. size 

 Photo, by W. H 

 C. P. 



walls of this tube, and travel on until they make their way out 

 through the sldn to the surface. Another injurious species is 

 the sheej) l5ot-fly, whose larvse cause "staggers" in sheep. 



The flower-flies (SyriDhidse^), like the bot-flies, mimic honey- 

 bees, bumlilel^ees, and wasps. The adults feed on the pollen 

 and nectar of flowers, and even imitate the 

 humming of the bee. The larvse of some 

 forms feed upon plant-lice ; others, upon de- 

 cajang vegetable matter. They may occupy 

 the nests of various stinging Hymenoptera. 

 The larvae of some species are known as rat- 

 tailed maggots on account of their ha^dng 

 a characteristic appendage. These are some- 

 times found floating in foul water or even in 

 salt water (Fig. 84 a). 



The robber-flies are usually of large size, 

 have a short head, prominent eyes, legs covered with stiff hairs, 

 and aVxlomen either long and slender (Fig. 85) or stout. 

 These flies attack and devour other flies and even insects much 

 larger than themselves, such as bumblebees and dragon-flies. 

 The horse-flies include the largest flies, and those whose 

 bite is the most painful (Figs. 86, 87). The female sucks the 

 blood of various short-haired domestic animals, especially of 

 horses and cattle. The male, however, feeds on flowers. The 

 lar\-i:e are carnivorous and live in the earth or ■water. 



The long-horned flies (Nematocera) have generally slen- 

 der bodies and long antennce composed of six or more joints. 

 The larva; arc frequently aquatic or infest plant tissues, but 

 are not parasitic upon animals. To this suborder belong the 

 black-flies, gall-gnats, mosquitoes, and crane-flies. 



- syrphos, a Greek name for a gnat. 



