COCCIDAE — SCALE-INSECTS 



595 



the young Coccids are all similar, male and female being indistin- 

 guishable. A difference 

 soon appears, with the 

 result that the male, after 

 passing through more 

 than one pupal condi- 

 tion, appears as a winged 

 Insect. The female never 

 becomes winged, but, if 

 we may judge from the 

 incomplete accounts we at 

 present possess, her de- 

 velopment varies much 

 according to species. In 

 some she retains the legs, 

 antennae, and mouth- 

 organs ; in others she 

 loses these parts, though 

 retaining the original 

 form in a general manner ; 

 while in a third {Mar- 

 garodes) she becomes en- 

 cysted, and apparently 

 suffers an almost com- 



FiG. 290. — Instars of Dadt/lopius citri. (After Ber- 

 lese.) A, Egg ; B, youug larva ; C, first male 

 nymph ; D, second male nymph ; E, adult male ; 

 F, adult female. All equally magnified. x 20. 



plete histolysis, reappearing after a very long period (it is said 

 it may be as much as seven years) in a considerably altered form. 

 The post-embryonic development of Aspicliotus nerii has been 

 studied by Schmidt ^ and Witlaczil,^ whose accounts agree except 

 as to some points, such as the number of ecdyses. The young, or 

 larva, is hatched with fairly well-developed legs, antennae, and 

 rostrum ; there is no external difference between the sexes. The 

 larva selects some spot on the plant and drives its rostrum therein, 

 thus becoming fixed ; moults occur, and the body excretes waxy 

 matter from its sides in processes that fell together and form the 

 shield; the female becomes much larger than the male. The 

 legs and antennae of both sexes disappear, so that the power of 

 movement is completely lost. The mouth-parts also atrophy. The 

 female after this undergoes no further change, except that of 

 growth in connection with ovarian development. The male, 



1 Arch. Naturgesch. li. i. 1885, p. 169. " Zeitschr. wiss. Zool. xliii. 1886, p. 156. 



