370 



General Biology 



a combination of six feather dusters and thirteen damp sponges. While 

 the constant 'cleaning' movements of flies are clearly designed to rub 

 off and scatter the adhering germs everywhere they go." 



There are "little house flies" (Fannia canicularis) which probably 

 most people believe grow into the regular house flies. Their breeding 

 habits and feeding places are quite similar to house flies, but, as flies 

 hatch in the adult form they do not grow after once becoming flies. 



Other flies, such as bluebottles, greenbottles, and flesh flies or blow- 

 flies, are also found about the home and frequently lay their eggs on 

 meat. These flies are scavengers. 



In the south there is the screw-worm fly (Chrysomyia macellaria) 

 which deposits its eggs on wounds, for the maggots of this species feed 

 on living flesh. It is these flies also which are likely to lay their eggs 

 in the nostrils and ears of children or even of adults as they sleep out of 



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Fig. 241. 



I. Typhoid fever or house-fly (Musca domestica). a, Adult male; b., pro- 

 boscis and palpus of same; c, terminal joints of antennae; d., head of female; e., 

 puparium; /.. anterior spiracle; all enlarged. (Howard and Marlatt, Bull. U. S. 

 Dept. of Agriculture, 1896.) 



II. Metamorphosis of Saw-Fly. 



III. Tsetse fly, which causes a disease of cattle in Africa, enlarged. (L. 

 O. Howard.) 



IV. Larvae of bot flies attached to the walls of the stomach of a horse. (.After 

 Osborn.) 



