164 THE STUDY OF INSECTS. 



Family COCCID^: (Coc'ci-dae). 

 The Scale-bugs or Bark-lice, Mealy-bugs, and otJiers. 



The family Coccidae includes the Mealy-bugs, the Scale- 

 bugs or Bark-lice, and certain other insects for which there 

 are no popular names. In this family we find those mem- 

 bers of the Hemiptera that depart most widely from the 

 type of the order. In fact this is a very anomalous group, 

 the species differing greatly in appearance, habits, and meta- 

 morphoses from those of the most closely allied families. 

 Not only do the members of this family appear very unlike 

 other insects, but there is a wonderful variety of forms within 

 the family, and even the two sexes of the same species differ 

 as much in the adult state as members of distinct orders. 



The males of Coccidae, unlike all other Hemiptera, 

 undergo a complete metamorphosis. The adult males have 

 only a single pair of wings, the hind wings being represented 

 by a pair of club-like halteres. Each of these is furnished 

 with a bristle, which in all the species we have studied is 

 hooked, and fits in a pocket on the wing of the same side 

 (Fig. 202). The male in the adult state has no organs for 

 procuring food, as the mouth-parts disappear during the 

 metamorphosis of the insect, and a second pair of eyes ap- 

 pear in their place. The adult female is always wingless, 

 and the body is either scale-like or gall-like in form, or grub- 

 like and clothed with wax. The waxy covering may be in 

 the form of powder, of large tufts or plates, of a continuous 

 layer, or of a thin scale, beneath which the insect lives. 



Among the Coccidae are found many of the most serious 

 pests of horticulturists. Scarcely any kind of fruit is free 

 from their attacks, and certain species of scale-insects and 

 mealy-bugs are constant pests in conservatories. The ease 

 with which these insects or their eggs can be transported 

 long distances while yet alive, on fruit or living plants, has 



