HEMIPTERA 



95 



because it appears in August, completes its life round in 

 only two years. The numerous pupal or nymph cases 

 seen on the trees in late summer are of this species. 



Plant Lice (Aphidae) 



The plant lice have a remarkable life history. Most 

 of them pass the winter in the egg state. At the first 



FlQ, 103. Eggs of plant lice on a maple tree in October. Photograph three times 

 natural size. 



appearance of leaves in the spring, the eggs hatch into 

 wingless females, no males being found until late in summer. 



