THE COMMON INSECT ENEMIES OF THE PLUM 1187 



them migrate to the leaves, causing them to curl and turn yellow. 

 The scales produce honeydew, which accumulates on the tree and 

 becomes infested with a black fungus, thus giving the tree an un- 

 sightly sooty appearance. 



Control. Lime-sulphur wash as used for the San Jose scale 

 should keep this species in check. Kerosene emulsion and mis- 

 cible oils applied in spring as the buds begin to swell have also 

 been recommended. 



INSECTS ATTACKING THE LEAVES AND STEMS 



The Plum Plant Louse 



The eggs of the plant louse, Myzus mahaleb Fonscolombe, are 

 deposited in fall on the terminal twigs of plum trees. In spring, 

 light green wingless aphids hatch from these eggs and make their 

 way to the terminal growth, where they breed until late spring. 

 At this time winged migrants are produced, and the lice leave the 

 plum to breed during the summer on various plants. With the 

 approach of fall they return to the plum. 



The Hop Plant Louse 



This species, Phorodon huniuli Schrank, is very similar in 

 habits and appearance to the preceding aphis, from which it may 

 be distinguished by minute structural differences. The lice breed 

 on the plum during fall and spring, migrating to hops during the 

 su miner. Although this is a serious pest of hop vines, it is seldom 

 abundant enough on the plum to be seriously injurious. 



The Mealy Plum Louse 



This aphis, Hycilopterus arundinis Fabricius, is of a pale green 

 color marked by three longitudinal dark stripes, and covered by a 

 whitish mealy powder. The lice spend the summer on various 

 grasses, breeding on the plum during fall and spring. 



The Rusty-brown Plum Aphis 



This reddish-brown plant louse, Aphis setarim Thomas, is especi- 

 ally injurious in the South, and it sometimes becomes a serious 

 pest in our own section. The life history is similar to that of the 

 preceding species. 



