138 



AN INTRODUCTION TO ENTOMOLOGY. 



AA. Body of insect covered by a scale composed in part of moulted skins and 

 partly of a secretion of the insect. 3. DIASPHSUE. 



Sub-Family I. COCCIN^E. 



The sub-family Cocclnce includes those Coccids of which the 

 females undergo the least change in form during their development. 

 The majority of them retain a form not much different from that of 

 the young larvae ; but in some genera the body becomes a globular 

 mass, with little or no indication of segmentation. The most im- 

 portant characters, as the family is now understood, are the multi- 

 articulate labium, and the absence of anal plates. Plate IV. i<^rep~ 

 resents the typical form of the female adult in this sub-family; \e 

 represents the caudal end of the body of the same. The most com- 

 mon exception to this form is that of the genus Kermes described 

 below. In most genera of this sub-family the body of the female 

 becomes enclosed in a cottony or felt-like sac. In some, as the 

 mealy-bugs, this takes place just before they begin to oviposit ; 

 while in other genera the greater part of the life of tlie insect is 

 passed within the sac. In this and the next sub-family the caudal 

 style of the male is short ; and the last abdominal segment bears a 

 pair of long waxy filaments. Each filament is supported by one or 

 more hairs, at the base of which are the spinnerets from which the 

 wax is excreted (Plate IV. \a and \b]. 



Mealy-bugs, Dactylopius. The mealy-bugs are the best known 



members of this sub-family, as they are 

 the most common and most noxious of 

 green-house pests. Fig. 122 represents 

 D. longifilis, a common species in green- 

 houses. D. destructor (Fig. 123) is an- 



FIG. 122. Dactylopius longifilis, 

 female, enlarged. (From the 

 Author's Report for 1880.) 



FIG. 123. Dactylopius destructor, 

 female, enlarged. (From the 

 Author's Report for 1880.) 



other common species, which differs in lacking the long filaments 



