Some Important Orchard Plant Lice 9 



The green apple aphis, hke the preceding species, causes Httle 

 curHng of the fohage at the Ijeginning of the season. Later its 

 activity resuhs in the most pronounced curhng. 



The rosy apple aphis, on the other hand, produces much curl- 

 ing of the foliage, probably Ijecause it devotes its attention more 

 exclusively to the leaves. 



Ijoth the green apple aphis and the rosy, especially the latter, 

 have done very serious injury to fruit, causing it to be knotted 

 and gnarled and never to reach a salal)le size. 



Recently it has been shown that plant lice can and do spread 

 fire l)light.- It is thought that such of them as hatch from eggs 

 which were laid in Ijlight cankers may carry the blight germ to 

 other parts of the tree. 



Fig. 3. Injury to fruit 



The extent of the injury depends upon the abundance of the 

 lice. When very plentiful the tree mav l)e almost defoliated 

 and the crop utterly ruined. In 191 5 the injury was general 

 throughout the state and orchards everywhere showed the work 

 of plant lice. The season of 19 16 showed a smaller amount of 



'Merrill, J. H., IQ17. Further data on ihc relation of aphides and fire 

 hlisht ( Bacillius aiiiyloronis ) . In jour. Ivcon. luit., v. 10, p. 45-47. 



