CHERRY. LEAVES CHERRY LEAF PLANT-LOUSE. 131 



it, and returns to guarding his flock of aphides, till another of 

 the small ants approaches, which is similarly seized, but with the 

 same result as before. After two or three such encounters he 

 seems to suspect that some mischance has thrown him out of his 

 proper latitude, and he walks around to take a survey of the 

 parts adjacent. He no sooner leaves the flock of lice than one of 

 the small ants hastens to them and rapidly passes its sting around 

 among them, hereby marking them as its own property. From 

 that moment the large ant ceases to notice them, and the small 

 ones gather around and commence rubbing and nursing them as 

 attentively as though they were old acquaintances. It is evidently 

 the pungent fluid of their stings which they throw around among 

 the aphides which render them repulsive to the large ant; and 

 when he first seized one of these small ants it was the suffocating 

 fume of this fluid which induced him to drop his victim so 

 hastily, for their sting is not powerful enough to penetrate the 

 hard horny outer surface of his body. 



It is somewhat remarkable that, so closely related to each other 

 as the different kinds of cherry trees are, the aphides which in- 

 fest one of these kinds of trees do not establish themselves upon 

 the others also. Yet we never see the black aphis of the garden 

 cherry invading any of our native or wild cherry trees, and these 

 appear each to have a species of plant-lice peculiar to them which 

 seldom if ever fix themselves upon the foliage of the other kinds. 

 Thus a species which I described in the Fourth Report of the 

 State Cabinet, page 65, under the name of the cherry-inhabiting 

 aphis (-#. Cerasicolens), pertains to our common black cherry. 

 Another species may here be noticed which infests the under sides 

 of the tender apical leaves of the choke cherry, curling their 

 margins downwards and inwards, and changing them to a paler 

 yellowish green color. It may be named and characterised as 

 follows : 



The Cherry Leaf Plant-louse (rfphis Cerasifolia), measures 0.08 to the 

 tip of its abdomen, and 0.15 to the end of its wings, which expand 0.26. It is 

 black with a pale green abdomen, which has three dark green dots on each 

 side forward of the nectaries, and above these a row of impressed deep green 

 dots extending backwards past the nectaries with a deep green stripe upon the 

 middle of the back which does not reach to the tip; the sutures are also of a 

 deeper green color; the nectaries reach half way to the tip and are dusky at 



