ORCHARD INSECTS OF THE PACIFIC NORTHWEST 



45 



BLACK CHERRY APHID 



The black cherry aphid (Myzus cerasi Fab.) is a large, shiny, 

 black aphid which occurs on the young foliage of cherry trees and 

 often interferes with the terminal growth. It is much more often 

 found on sweet cherry trees than on the sour varieties, and is particu- 

 larly injurious to young trees and to nursery stock. The leaves of 

 infested trees are severely curled (fig. 55) and covered with a sticky 

 honeydew. This aphid is a European species that has become 

 prevalent in the United States. 



LIFE HISTORY 



The winter eggs, which are tucked in among the buds, hatch 

 about the time the buds burst, and the young develop rapidly on the 

 new growth, curling the leaves and feeding within the protection 

 thus afforded. There are several generations. Winged adults develop 

 in the middle of the summer and migrate to water cress, peppergrass, 

 and other plants of the mustard 

 family. A later generation re- 

 turns to the cherry in the fall 

 and produces wingless individ- 

 uals that lay the overwintering 

 eggs. 



CONTROL 



Spraying after the leaves are 

 curled is of little use, but very 

 good control may be obtained 

 by spraying just as the buds are 

 breaking. Nicotine sulphate 

 (40 percent nicotine) may be 

 used in the proportion of three 

 fourths of a pint to 100 gallons 

 of water, with soap or casein 

 spreader, or added to dormant 

 sprays of lime-sulphur or oil. 



RED SPIDERS 



On cherry trees the common 

 red spider or 2-spotted mite ( Te- 

 tranychus telarius L.) is much 

 more injurious than other mites. 

 This species hibernates beneath 

 the fallen leaves or in other trash 

 and migrates into the trees in the spring as soon as the new leaves have 

 appeared. It is not often seen before June, and does its most serious 

 injury after the fruit has been picked. Cherry trees are frequently 

 neglected at this time and allowed to become dry; this condition 

 aggravates the injury caused by the mites and may very materially 

 reduce the succeeding year's crop by weakening the fruit buds. If 

 cherry trees have a dry and dusty appearance during the late summer, 

 it may be suspected that mites are on the trees. Closer examination 

 will reveal the webbing, in which the small greenish or yellowish 

 mites are running about. More complete descriptions of this and 

 other red spiders will be found on page 16. 



Figure 55.— Injury to cherry foliage by the black 

 cherry aphid. 



