HOMOPTERA 



455 



In a few genera the female does not molt the second exuviae*; 

 the body shrinks away from it, and transforms within it. In such 

 cases is it termed a puparimn. Figure 535 represents the scale of 

 Fionnia fionnicB; here the puparium can be seen through the trans- 

 parent scale. 



Fig. 533. — Kermes sp. on Querciis agrifolia : adult females on the stem ; immature 

 males on the leaves. 



The shape of the scale, and the position of the exuviae on it, fur- 

 nish characters that are very useful in the classification of the 

 Diaspidinas. 



To this subfamily belong some of the most serious pests of shrubs 

 and trees, as, for example, the San Jose scale and the oyster-shell scale. 

 The following are a few of the many well-known species of this very 

 important subfamily. 



*The term exuvice is a Latin word which had no singular form, the plural 

 noun being used as is in Enghsh the word clothes. Some recent writers use the 

 term extivia for a single molted skin. 



