126 CHERRY. LEAVES CHERRY PLANT-LOUSE. ITS NUMBERS. 



numbers which thus make out to stow themselves within a nar- 

 row compass are almost incredible. Upon the under surface of a 

 small leaf three-fourths of an inch long and half an inch wide I 

 have counted upon one side only of the mid-vein one hundred 

 and ninety of these lice. Yet this leaf was not more densely 

 covered than many others. The two surfaces of a small leaf but 

 an inch long would therefore furnish ample space to accommo- 

 date a thousand of these insects. 



As all the leaves are tender and juicy early in the season the 

 aphides multiply rapidly, and in about a month after the first in- 

 dividuals make their appearance, namely, between the 15th and 

 25th of June, as I find the dates entered several times in my notes 

 taken in different years, some of the trees become literally over- 

 run with these vermin, their black bodies covering not only the 

 under sides of the leaves but also the leaf-stalks, the tender suc- 

 culent ends of the twigs, and sometimes the green young cherries 

 and their stems; whilst a swarm of flies, wasps and other insects, 

 attracted to them to feast upon their honeydew, keep up a con- 

 stant buz and hum around the infested trees during warm sunny 

 days. The leaf of the cherry, however, is of such a tough coria- 

 ceous texture that it does not become curled and corrugated like 

 those of most trees when similarly circumstanced. Its edges 

 merely turn backwards or become slightly rolled. The tips of 

 the twigs, however, and the young leaves growing from them, 

 having their juices pumped out and drained by such a multitude 

 of tiny beaks, shrivel and die, looking as though they had been 

 scorched by fire; and the whole tree would soon perish, it is evi- 

 dent, if this severe infliction was protracted. But when the 

 aphides become thus numerous their natural enemies and de- 

 stroyers are attracted to the tree and multiplied in such numbers 

 as to make the most astonishing havoc among this feeble race of 

 beings. Although single trees in my grounds have been equally 

 infested in some former years, I never knew them all to be over- 

 run with these lice as they were the 25th of June the present 

 year. It was evident if the evil continued the trees could live 

 but a short time. But on examination upon that day I found 

 two or three yellow larvae of the Syrphus flies upon almost every 



