FIELD BOOK OF INSECTS. 



Coccidae sometimes produce living young and reproduce 

 without sexual union, but these phenomena are not so 

 general as among the Aphididae. A single female Coccid 

 may give birth to thousands of young, but these do not 

 reach maturity as quickly as do the plant-lice. The males 

 of many species of scale-insects are unknown, probably 

 because their small size and short life have caused them 

 to be overlooked, rather than because they are rare or 

 absent. 



Three of the subfamilies are of especial economic im- 

 portance to us; they are the Dactylopinas or Mealy Bugs, 

 the Coccinas or Soft Scales, and the Diaspinas or Armored 

 Scales. 



Dactylopinae 



The female Mealy Bug undergoes but little change of 

 form as it matures and it is able to move about. No real 

 scale is formed, at most a sort of cottony sac, and this 

 usually only when the insect is nearly full-grown. 



A common species in greenhouses is Pseudococcus citri. 

 The oval body is bordered by a white fringe and covered 

 with a mealy deposit. The eggs are laid under the female 

 in a loose nest of sticky, white fibers in such quantities 

 that she is forced to stand on her head in order to feed. 



Phenacoccus acericola frequently occurs in great numbers 

 on maple leaves. The female is light yellow but covered 

 with a mass of powdery, slightly stringy, white wax about 

 three times her own bulk. 



Various species of Kermes occur on oak. The adult 

 females are relatively large and look like galls. 



Coccinae 



The Soft Scales are usually of considerable size as com- 

 pared with other scale-insects; their surface is rather 

 waxy and their form more or less convex. Such "scale" 

 as they have is merely the thickened surface of the insect 

 itself and not a separate structure. 



Females of Pulvinaria secrete a mass of cottony material 

 in which they place their eggs. P. innumerabilis is the 



92 



