The Scale Insects 



Fig. 149. — Cottony Maple Scale, Pulvinaria 

 innumerabilis. (Author's illustration.) 



most abundant in 

 species of which is 

 the group known as 

 the armored scales 

 (subfamily Diaspinae), 

 so termed because the 

 insect soon after set- 

 tling begins the secre- 

 tion of a scale by 

 means of threads of 

 wax exuding from 

 pores in the body 

 which eventually 

 blend together and 

 form an impervious 

 covering separated 

 from the insect's 

 body. The shape and 

 character of this scale is of importance in the classification of 

 the group but the most important characters are found in the anal 

 plate of the body of the female insect. A second large group 

 well represented in the United States is the group of naked bark- 

 lice, known as the subfamily Lecaniinae. In this group no true 

 scale is formed and the body is usually well arched so as to 

 become almost hemispherical. The third group (subfamily 

 Coccinae) comprises those forms known as mealy-bugs and re- 

 lated forms. These insects have no differentiated scale but are 

 all covered with a white waxy secretion, some of them having 

 conspicuous waxy egg sacs at the end of the body of the female. 

 The majority of species of scale insects at present found in 

 the United States are not indigenous to this country, but have 

 been introduced from abroad, most of them from European 

 regions, on plants and young trees and on fruit carried to this 

 country in the course of commercial interchange. 



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