mSECT-EATING BIRDS. 



197 



or plant-lice wliicli are found on almost all kinds of plants are 

 produced in spring from eggs laid the season before, and 

 through the summer only females are developed. At the 

 last of the season 

 males and fe- 

 males both ap- 

 pear, and eggs 

 are laid for the 

 brood which 

 hatches early in 

 the spring. Reau- 

 mer says that one 

 individual in one 

 season may be- 

 come the progen- 

 itor of six thou- 

 sand millions. Fig. 6.— Chuck-wlUs WidowT 



The silk-worm moth produces about five hundred eggs ; the 

 great goat-moth about one thousand ; the tiger-moth one 

 thousand six hundred ; the female wasp at least thirty thou- 

 sand. There is a species of white ants, one of which de- 

 posits not less than sixty eggs a minute, giving three thou 

 sand six hundred in an hour. How then shall this enor- 

 mous mass of insects be kept in check ? What shall prevent 

 them from overrunning the country, destroying the crops and 

 devastatino; the land ? 



FOOD OF BIEDS. 



Various causes operate to check 

 the undue increase of insects, and 

 the chief of these is the appetite 

 and instinct, which a wise Provi- 

 dence has given to birds. If the 

 number of eggs produced by in- 

 sects is wonderful, the number de- 

 stroyed by a single bird is no less 

 so. Audubon says a woodcock will 

 eat its own weight of insects in a 

 single night. Dr. Bradley says 

 that a pair of sparrows will de- 



Fig. 7. — Woodpeckers. 



stroy three thousand three hundred and sixty caterpillars in a 



