THE JIG USE-FLY. 



375 



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. 345), Melanactes, and the young of a snapping beetle. 



Fig. 347. Bot-fly of the ox and its larva. 



We now come to the second series of orders, the Meta- 

 lola. 



Order 6. Diptera. The common house-fly (Fig. 346) is 

 a type of this division, all the members of which haye 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. 347, 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. '348, Syrphus politus Say) mimic 

 wasps ; they are most useful in devouring aphides. 



