12 



K. Takahashi 



Dift'ercuces between the winged 

 and wingless forms in the nymphs?. 



In the first und second instars, the nymphs of the winged form usually do 

 not differ from the corresponding stages of the wingless form, but in the third and 

 fourtli instiirs they always differ structurally. 



However, as already stated, in some species of Hormaphidina, the nymphs 

 of the winged form even in the first iustar are distinctly different from those 

 of the wingless in tlie number and distribution of the wax-pores on the body. This 

 might be taken as an indication in some species at least that whether the aphida 

 become winged or wingless is not determined by the external factors after being laid. 

 In some Hormajjhidina, as already stated, the antennae and legs of the nymphs of 

 the alcyrodiform female become more rudimentary as the growtli proceeds, while 

 those of the nymphs of the winged form become better developed in the later instars. 



In the third instar of the M'inged form, the mesothorax is developed, the wing- 

 pads begin to appear, and the third antennal joint is often longer when compared 

 with tJiat of the corresponding stage of tiie wingless form. The tliird antennal 

 joint of ihv winged form, in some species, as Oreij/na hamhimfo'iae Takali. and 

 others, is longer when compared with that of the wingless form even in the second 

 instar, and in the grown nymphs of some Hormaphidina and Pemphigina, tlie anten- 

 nae of the winged form are longer and with moi'e joints than tliose of the 

 apterous form. In the fourth instar of the winged form, the wing-pads are well- 

 developed. 



The eyes of Orcijma, CerutupliAS. Jleurodaphis, Astogojjteri/x, Cervaphis, 

 Ncoiiln/Uiijihix and others are composed of three facets in all the instars of the wing- 

 less form, as well as in the first three instars of the winged, but in tlie fourth iustar 

 of the winged form, as well as in the winged adults, they are coniposed of numerous 

 f;u-ets. 



In the genera <.)rc<jmu, ^Uenrodaplils, jtsteijoj>lcr//x, Vcrvupliis, Ncophijlhtiiliif!, 

 Grecuidea and otliers, the head and pronotum which are usually defined in the 



