APPLE LEAVES, PLANT-LOUSE ITS FECUNDITY. 51 



insect depredators will be destroyed and the health of the tree 

 promoted. These eggs hatch quite early, as soon as the buds 

 begin to expand, and the young lice locate themselves upon the 

 small, tender leaves, inserting their beaks therein and pumping 

 out their juices. All of the lice thus hatched are females, and 

 reach maturity in ten or twelve days. Without any intercourse 

 of the sexes, these females that were produced from eggs, now 

 commence giving birth to living young, bringing forth about two 

 daily, for a period of two or three weeks, when having become 

 decrepid with age, they perish. The young mostly locate imme- 

 diately around the parent, as closely as they can stow themselves. 

 Upon a young leaf, in a space less than half an inch long and the 

 tenth of an inch wide, I counted thirty-six young lice and four 

 winged females, which Lad recently alighted there to begin a new 

 colony. The young reaching maturity after a similar length of 

 time in their turn become parents. Thus these vermin continue 

 to breed, and as fast as new leaves expand they are in readiness 

 to occupy them. When favorable circumstances attend them, 

 their multiplication surpasses all power of computation. In the 

 warmth of summer they attain maturity in less than half the time 

 they do early in the spring. And like most of the species of the 

 Aphides they at this period of the year produce winged as well 

 as wingless females, the former dispersing themselves to found 

 new colonies upon other trees. It is reported of the insects of 

 this family, that there are from sixteen to twenty generations 

 in the course of the season, from twenty to forty -young being pro- 

 duced from each parent. Thus, from one egg, as stated by Mr. 

 Curtis, in seven generations, 729 millions of lice will be bred. 

 And if they all lived their allotted length of time, by autumn 

 everything upon the surface of the earth would be covered with 

 them. When cold weather begins to approach, males as well as 

 females are produced, and their operations for the season close 

 with the deposit of a stock of eggs for continuing their species 

 another year. On the last day of last October, it being a warm 

 sunny day, after many nights of frost, I observed myriads of 

 winged and apterous lice wandering about upon the trunks, the 

 limbs and the fading leaves of all my apple trees, many of them 

 occupied in laying their eggs. These were scattered along in 



