INSECT TRANSFORMATION 



Very different is the fate of the larva destined to develop 

 into a female scale-insect. Resembling closely the male larva 

 during the first stage, she passes into a similar quiescent con- 

 dition beneath a protective scale of distinctive form (Fig. 49 

 a c). For the rest of her life she remains with feelers and legs 

 vestigial or absent, her body increasing in size so that she be- 

 comes considerably larger than her mate, but with the develop- 

 ment so arrested or degraded that when the adult state is 



FIG. 49. MUSSEL SCALE-INSECT (M 'ytilaspis pomorum). 



a, female (ventral view) showing eggs protected by " scale " ; b, female (dorsal 

 view), x 24. d, male "scale," x 12. c, female, and e, male "scales" on 

 twigs, natural size. From Howard, Yearbook, U.S. Dept. Agric., 1894. 



attained she seems to be little more than a limbless egg-bag. 

 Among the " mealy bugs " members of the genera Dactylopius 

 and Pseudococcus for example the female (Fig. 50) does not 

 lose her feelers and legs ; she is able, therefore, to move about 

 and, though she never acquires wings, she does not undergo 

 the extreme degeneration noticeable among the true scale- 

 insects. The waxy secretion forms a threadlike or felted 

 covering for the female's body, often extending over the eggs 



