THE APPLE-TREE LOUSE. 433 



ored, thickened spots appear, and before the spores 

 are developed. (Ber/celej/.) 



3. Insects. (1) Apjjle-tree Louse — Aphis mali. 

 This is a small, green insect, which crowds upon the 

 tips of the young shoots, and of the leaves. It 

 sucks the juice of the tree, and causes the leaf to 

 curl under. This provides it with a shelter from 

 the dew and rain. It is very prolific. In the 

 autumn the male and female produce eggs, which, 

 during the winter, are laid in the crevices of the 

 bark. The females are hatched early in the spring, 

 and arrive at maturity in a few days. Without any 

 intercourse with those of the opposite sex in this 

 generation, they give birth to living young, bringing 

 forth about two daily for a period of two or three 

 weeks. The young soon become parents, and they 

 are thus multiplied almost inconceivably. From 

 twenty to forty generations are produced in a single 

 season. Mr. Curtis states that, from a single e^^, in 

 seven generations, seven hundred and twenty-nine 

 millions of lice will be bred, if unmolested ; and if 

 they all lived the allotted time, by autumn every- 

 thing upon the face of the earth would be covered 

 with them. 



On this account it is a source of gratitude that 

 Providence has given this insect so many enemies ; 

 perhaps no other has an equal number. These are 

 wasps denominated Crabonidae, and a number of 

 flies called golden-eyed and lace-winged. But one of 



