378 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



manure, the others breeding in cow manure, human excrement 

 or other filth. Each female lays from 120 to 150 eggs at a 



FIG. 166. The house-fly, Musca domestica. (Eight times natural size.) 



time, and may lay five or six batches of these at intervals of a 

 few days. These eggs hatch in ten to twenty-four hours, and 



