i68 



THE STUDY OF INSECTS. 



Mealy Bugs are the most common and the most noxious of 

 green-house pests ; and in the warmer regions, as in Florida, 

 they infest plants in the open air. Two species are shown 

 greatly enlarged in Figures 204 and 205. These insects are 

 extremely difficult to combat, as the white powder with 

 which the body is clothed protects them from the sprays 

 and washes ordinarily used. 



Kcrincs, — Species of this genus are common upon oaks 

 wherever they grow. These insects are remarkable for the 

 wonderful gall-like form of the adult females. So striking is 

 this resemblance, that they have been mistaken for galls by 

 many entomologists. Figure 206 represents a species of this 

 genus upon Qiiercus agrifolia. The gall-like swellings on the 

 stem are the adult females ; the smaller scales on the leaves 

 are the immature males. 



Orthczia (Or-the^zi-a). — The members of this genus 



occur not uncommonly on vari- 

 ous weeds. They are remark- 

 able for the calcareous secretion 

 with which the body is clothed. 

 This is in the form of long 

 plates. Figure 20J represents 

 a nymph ; in the adult female 

 the secretion becomes more 

 elongated posteriorly, and 

 forms a sac containing the eggs 

 mixed with a fine down. Later 

 when the young are born, they 

 remain in the sac till they have 

 themselves secreted a sufficient 



^"- ^.J^.C!r':'^kv^^^^^^ amount of the lamellar matter 



to cover them. 

 Pithnnaria (Pul-vi-na'ria). — This genus includes species 

 in Avhich the body of the female resembles Lecanium, de- 

 scribed below, but which excrete a large cottony egg-sac. 

 This eee-sac is not ribbed, but 'is of the form shown in 



