336 AGRICULTURE OF MAINE. 



a. PLANT LICE. 



Besides the woolly aphis which does its chief damage to the 

 apple roots, several species of aphids attack the leaves, and 

 tender stems. These are minute insects about % of an inch 

 long. They pierce the tissue of the shoots with their beaks 

 and suck the sap or infest the leaves causing them to curl, or 

 become sickly. Some species of these pass their whole life 

 upon the apple while others spend part of the year on other 

 plants. But as all the important species return to the apple 

 twigs to lay eggs in the fall and as they resemble one another 

 closely, both in appearance 'and manner of injury, it is not 

 necessary to discuss more than two species here. 



Aphids are frequently attended by ants which are attracted 

 by honey dew, a sweet secretion of the aphids, and the presence 

 of ants about the apple leaves is a pretty certain sign of aphid 

 infestation. 



Lady beetles (figs. 52, 53) both in the adult and larval stage 

 feed greedily upon aphids and should not be mistaken for in- 

 jurious insects. Syrphus maggots also are among the most 

 beneficial insects in the State in this respect, as they destroy 

 aphids in great numbers. 



I. Green Apple Aphis. 

 (Aphis pomi De G.) 



The body is pear-shaped, the colors being yellowish green, 

 greenish, or darker, varying considerably in detailed markings 

 and in the sever^ generations. 



Winter eggs (fig. 30) are deposited by the sexual females in 

 the fall. They hatch in the spring, and, like the species next 

 considered, the aphids developing from them cause a curling 

 of the leaves. The green apple aphis infests the apple through- 

 out the year. Upon the hatching of the winter eggs in spring 

 a succession of agamic generations is produced, the earlier 

 ones, except the first, with numerous winged individuals which 

 migrate to other trees and establish new colonies. 



