PARASITISM AND DEGENERATION 



365 



loses most of its outward resemblances to the other members 

 of its class (Fig. 225, e}. 



Certain insects live sedentary or fixed lives. All the mem- 

 bers of the family of scale insects (Coccida?), in one sex at 

 least, show degeneration that has been caused by quiescence. 

 One of these coccids, called the red orange scale, is very 



FIG. 225. Three crustaceans and their larvse : a, Prawn, Peneus; b, Peneus, larva; 

 c, Sacculina, parasite; d. larva Sacculina; e, barnacle, Lepas, quiescent; /, larva 

 of barnacle. (After Haeckel.) 



abundant in Florida and California and in other orange-grow- 

 ing regions. The male is a beautiful, tiny, two- winged midge, 

 but the female is a wingless, footless little sac without eyes or 

 other organs of special sense, and lies motionless under a 

 flat, thin, circular, reddish scale composed of wax and two 

 or three cast skins of the insect itself. The insect has a long, 

 slender, flexible, sucking beak, which is thrust into the leaf or 

 stem or fruit of the orange on which the " scale bug " lives and 

 through which the insect sucks the orange sap, which is its only 

 food. It lays eggs or gives birth to young under its body, under 



