118 PLUM, PEACH, AND CHERRY INSECTS 



where they become attached. In the fall they migrate to the under 

 side of the branches (Fig. 141). 



Control. Commercial lime-sulfur may be used as a spray 

 against this insect, applying it before the leaves appear. The 

 spraying may be repeated in July, employing the summer strength. 

 Directions for using this are found upon the can. 



ATTACKING THE LEAVES OF PLUM 



The Plum Gall-mite. This is not an insect, but an allied form 

 belonging to the branch of the animal kingdom known asArach- 

 nida. Like other members of the group, it has, in the adult 

 stage, eight legs instead of six. It is sometimes called the Pear- 

 leaf Blister-mite. (See page 1 10) . It is barely visible, but is destruc- 

 tive, in that by its work it causes 

 the leaves to become distorted 

 into the peculiar galls shown in 

 the illustration (Fig. 142). 



Control. The only method 

 of control that can be suggested 

 at this time is to pick off and 

 burn the abnormal leaves, thus 

 destroying the pests within. 

 Commercial lime-sulfur is used 

 ^ as a dormant spray to destroy 



the winter forms. 



The Plum-leaf Aphis (Hyo- 



lopterus arundinis). The eggs of this aphis are laid on the plum 

 twigs in the fall and hatch in the spring. Two or three genera- 

 tions are developed in the early summer on the plum, and then the 

 insect migrates to other food plants, returning to the plum in the 

 fall. This migration is accomplished by winged generations. 



Injury. This louse is extremely injurious in that it sucks the 

 juices of the leaves and tender twigs, causing the leaves to drop 

 prematurely, checking the growth of the tree and preventing the 

 proper fruiting. If it occurs hi large numbers, the tree appears 

 blighted. 



Control. About a week before the buds open, spray the trees 

 with one of the tobacco extracts, such as Black Leaf 40; or 

 us'e whale oil soap, one pound to fifty gallons. Trees sprayed with 

 lime-sulfur for the twig borer just before blossoming should not 

 be troubled with aphids. This compound might also be used on 



