APHIDS 



51 



(Black Leaf "40" 1 to SOO or Black Leaf 

 1 to 50). A badly infested tree will re- 

 quire three gallons or more. The lice 

 hibernating on the trunk can be destroyed 

 by a winter application of lime-sulphur. 

 The stock of the Northern Spy Apple is 

 resistant to the Woolly Aphis. 



Pe.\r. See Apple. 



Quince. See Apple. 



Pomegranate. See Apple. 



PLUM .VJfD PBUIVE 



Tlie Mealy Plum Aphis 



Hyalopterus anindinis Fabr. 

 This is a longish, rather narrow aphid. 

 It is pale green in color and is covered 

 with a whitish mealy powder. It inhab- 

 its the plum during winter and spring, 

 often becoming intensely abundant on 

 the leaves during March and April. In 

 May the great majority of the lice be- 

 come winged and migrate to grasses, but 

 a few remain on the plum during the 



Fig. 9. Effect of Woollj 



Aphis on Root. 



— EssiK. 



Fig. 8. 

 Twigs. 



Galls Caused by "Woolly 



Aphis on 

 — Essig 



summer. Migrants return in October to 

 the fruit trees and produce the sexed 

 forms. The winter eggs are laid on the 

 twigs around the axils of the buds. This 

 aphid is a cosmopolitan species and is 

 probably of European origin, and it and 

 the two following plum plant-lice may 

 be controlled in the manner advised for 

 the Green Apple Aphis. 



The Hop Aphis 



Phorodon humuli Schrank 

 This is a pale green non-pulverulent 

 aphid at times injurious to plums. Its 

 life history is similar to the preceding 

 species, the alternate host-plant being the 

 hop. 



The Rusty-brown Plum .Vpliis 

 Aplii.s seUiriae Thos. 

 This is a small rusty-brown aphid 

 which often infests the young leaves and 



