84 NORTH AMERICAN INSECTS. 



vember nearly twenty generations are born ; and if their 

 number were not checked by their numerous enemies, as 

 well as by wet, damp weather and cold winters, all of our 

 vegetable productions would not suffice to nourish them. 



The principal species of this country, which may be seen 

 and examined every where, are : 



The ROSE-LOUSE (Aphis rosce\ which is green. 



The PIG-NUT LOUSE (Aphis caryce\ which is the largest, viz., one 



quarter of an inch long, and covered with 



a bluish woolly substance. 

 The CABBAGE-LOUSE (Aphis brassier), covered with a white mealy 



substance. 

 The WILLOW-LOUSE (Aphis salicis), which is black. 



Shield-lice (Coccus). 



The SHIELD-LOUSE, also called Bark-louse, or Scale In- 

 sect, is found upon the branches and leaves of trees and 

 bushes, upon which it sits motionless, as if it were glued 

 on, looking more like a wart than a living creature. This, 

 however, is the case only with the female, who inserts her 

 snout into the branch upon which she sits, and remains 

 there imbibing the sap of the plant. In this condition also 

 she deposits her eggs, and after having done so she dies 

 upon the same spot, leaving her dead and dried body a 

 cover and shelter to her young ones. The males have no 

 snout, and walk about the branches at their pleasure. 



The body of the Shield-louse is oval, and the head, tho- 

 rax, and abdomen run into one- another so imperceptibly, 

 that the whole appearance of the animal is like that of a 

 shield or buckler. Hence its name. 



I have before remarked, and I may often have occasion 

 to repeat the remark, that to the lover of Nature nothing, 

 even the most vile and insignificant object that lives, is 

 without some points of interest each has something curi- 

 ous in its construction or mode of life, or manner of rcpro- 



