ECONOMIC ZOOLOGY 



it away in disgust, but many a housekeeper will fish half a dozen filthy 

 flies out of the milk pitcher and "shoo" them off the cake without a 

 thought. To most persons " all flies look alike " and they do not realize 

 the number of species that are a pest to man and to the lower animals. 



FIG. 69. The house-fly, Musca domestica. (After Doane, Insects and Disease.) 



For example, the sheep bot-flies lay their eggs in the nostrils of sheep and 

 when the larvae hatch they crawl up into the frontal sinus causing 

 great suffering to the sheep and loss to the owner. 



The horse bot-flies lay their eggs on the body of the horse and when 



