442 



AN INTRODUCTION TO ENTOMOLOGY 



are either wingless or have vestigial wings. The fore wings 



are usually large, com- 

 pared with the size of the 

 body; the hind wings are 

 always greatly reduced in 

 size; usually they are a 

 pair of club-shaped hal- 

 teres, but in a few forms 

 they are more or less 

 ^ wing -like. Each hind 



Fig- 513-— Wing of Pseudococcus. (From Patch.) ^^^^ -g fu^^jghed with a 



bristle, which is hooked at the end and fits into a pocket or fold 

 on the inner margin of the fore wing of the same side ; in a few spe- 

 cies there are two or three or more of these hamuli. 



The venation of the fore wings is greatly reduced; a wing of 

 Pseudococcus (Fig. 513) will serve to illustrate the usual type of wing- 

 venation found in this family. 



The legs are wanting in many adult females, having been lost 

 during the metamorphosis. In adult males they are of ordinary 

 form; except in a few species, the tarsi are one-jointed, and each is 

 furnished with a single claw. Accompanying the tarsal claw there 

 are often a few long, clubbed setce, the digitules (Fig. 514) ; these are 

 tenent hairs ; some of the digi- 

 tules arise from the tip of the ^^-"--i ^.""'X^ — —.^ d 

 tarsus, and some from the 

 claw. 



The caudal end of the ab- 

 domen of the male usually 

 bears a slender tubular pro- 

 cess, the stylus. In some spe- 

 cies the stylus is as long as or even longer than the abdomen; in others 

 it is short, and in some it is apparently wanting. The stylus serv^es 

 as a support for the penis, which is protruded from it and in some 

 species is very long. 



The female coccid 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. 



The eyes of coccids exhibit varying degrees of degeneration and 

 retardation of development. The extreme o£ degeneration is found 

 in the females, where there is only a single simple eye on each side 

 of the head; this is probably a vestige of a compound eye. In the 

 adult males of the more generalized forms, compound eyes are present ; 

 and in some of these forms, there are also ocelli, two in some and three 

 in others. When compound eyes are present the facets are usually 

 large, and not closely associated. In the more specialized forms, 

 instead of compound eyes there are on each lateral half of the head 

 from two to eight widely separated simple eyes, which may be 

 scattered vestiges of compound eyes. 



Fig. 514. — Leg of a female Lecanium: 

 digitules. 



d, d. 



