THE HOUSE-FLY. 



355 



in all directions. A few beetles are phosphorescent. Such 

 are the fire-flies, the cucuyo of the West Indies, the glow- 

 worm, and certain grubs, such as Astraptor illuminator 

 (Fig. 340), Melanactes, and the young of a snapping beetle. 



Fig. 343.-Bot-fly of the ox and its larva. 



Order 13. Siphonaptera. The fleas (Fig. 341) are wing- 

 less, with sucking mouth-parts; all the palpi four-jointed. 



Order 14. Diptera. The common house fly (Fig. 342) is 

 a type of this division, all the members of which have but 

 two wings, while the tongue is especially developed for lap. 

 ping up liquids. The common house- 

 fly lives one day in the egg state, from 

 five days to a week as a maggot, and 

 from five to seven days in the pupa 

 state. It breeds about stables. 



The Tachina-fly is beneficial to man, 

 from its parasitism in the bodies of 

 caterpillars and other injurious insects. 



The bot-fly (Fig. 343, Hypoderma 

 lovis DeGeer) is closely allied to the 

 house-fly, but the maggot is much 

 larger. The larval bot-fly of the horse lives in the stomach, 

 that of the sheep in the frontal sinus. 



The Syrphus flies (Fig. 344, Syrphus politus Say) mimic 

 wasps ; they are most useful in devouring aphides, while in 



