FLIES. 133 



insects, and not being very good entomologists, 

 are deluded by the false appearance of these gay 

 deceivers, and so give them a "wide berth." 

 Thus Nature, through the operation of her laws, 

 has painted and given to these harmless flies 

 mimetic forms, that they may win in the great 

 struggle for existence. 



What curious life histories have many of the 

 flies ! The eggs of the different species are laid 

 in all kinds of situations, so that when the larvae 

 are hatched, each may find its own peculiar food 

 already at hand, on which it immediately begins 

 to eat and grow. Some kinds of maggots are 

 born in the nests of bees, and fed on the fat, 

 tender flesh of the bee larvas, that are carefully 

 tucked away in the cell cradles. The fly that 

 dares to enter such perilous places to deposit its 

 ova, must be dressed in bee's clothing, that the 

 little busybodies may not suspect that an inter- 

 loper is in their camp. On sunny days, quite 

 early in the Spring, if you are looking out for 

 such intruders, you will be most likely to find a 

 curious species darting here and there among the 

 cud-weed and first cinque-foil blossoms, .keeping 

 its conspicuously-colored wings extended, as it 

 hovers over a flower, as though it had learned the 

 trade of the humming-bird. This is a bee-nest 

 hunter. If it chances to alight, and you can cap- 

 ture it, you will see that its body is densely 



