254 Forty-second Report on the State Museum. [112] 



Although with no new observations to present upon this insect, the 

 inquiries recently made from some of the eastern fruit districts in 

 the State of New York, of means for preventing its injuries, call for 

 information in regard to it, and the following is, therefore, accordingly 

 presented, compiled from the writings of Dr. Fitch and other careful 

 observers : 



Myzus cerasi, the Aphis cerasi of Fabricius, is the common black aphis 

 of the garden cherry, Gerasus vulgaris — long known as quite destruct- 

 ive to cherry trees in Europe, whence it has doubtless been intro- 

 duced in this country. It is rare to find a tree that is wholly exempt 

 from it, and it often occurs in such incredible numbers upon the 

 underside of the leaves, that, completely covering them, it overflows 

 upon the leaf-stalks, the ends of the tender twigs, and even upon 

 the young fruit. The larger infested leaves do not carl but turn 

 backward or roll slightly. The more tender leaves upon the delicate 

 twigs being drained of their juices, shrivel and dry and die, as do 

 also the tips of the twigs. To such prodigious extent does this species 

 sometimes multiply, that a single young tree that had attained a 

 height of ten feet, harbored, according to a calculation made by Dr. 

 Fitch — by taking the average number on a single leaf, counting 

 the leaves on a branch, and the branches on a tree — at least 

 12,000,000 of individuals. 



Life-history. 



Its life-history, according to Dr. Fitch, who had not observed its 

 underground operations, is the following: It makes its appearance as 

 soon as the leaves put forth in the spring, hatching from eggs 

 deposited the preceding autumn. During the spring and summer, 

 winged and wingless forms are found; nearly all are without 

 wings, and all are females. They continue to produce living young 

 throughout the summer, which, when hatched, are smaller and of a 

 brighter color than when mature. They multiply with exceeding 

 rapidity, so that by the middle of June, in New York, the trees are 

 literally overrun with them. Toward the latter part of the month, 

 they are often attacked so vigorously by the larvae of Syrphus flies 

 and the lady-bugs {Coccinellidce) that their ravages are temporarily 

 checked and their numbers greatly diminished. If apparently exter- 

 minated, new broods shortly appear and resume their work, but they 

 are incapable of inflicting as serious harm upon the now mature foli- 

 age, as at their first advent. On the approach of cold weather, male 

 aphides make their appearance, and eggs are deposited at the base of 

 the buds and in the crevices of the bark for the continuation of the 

 species another year. 



