INSECT PESTS 157 



composed of both males and females are 

 produced, the sexes mate, and eggs are 

 laid which pass the winter on dead stems 

 or in the ground. According to present 

 knowledge the eggs hibernate on clover or 

 vetch. The sweet pea aphis derives its 

 food by sucking on the plant juices (fig. 



32). 



The sweet pea aphis is not only a pest 

 by itself, but it also aids in carrying the 

 virus of mosaic from plant to plant. 

 Moreover, plants which have their juices 

 constantly depleted by numerous sucking 

 aphids are thereby weakened and easily 

 fall the prey to diseases, especially streak 

 and anthracnose. If the green aphis could 

 be successfully controlled, nearly 80 per 

 cent of the other troubles would be pre- 

 vented from getting a start. 



Greenhouse sweet peas are not exempt 

 from the attacks of the aphis. In the 



