THE OPEN TYPE OF WING-GROWTH 75 



showing their characteristic features, though they are relatively 

 shorter than in the adult. The compound eyes have as yet 

 but few facets, and there are only four segments in the feeler 

 (Fig. 41 a), though the terminal one (the fourth) has the same 

 distinctive form as the sixth in the adult. After the first 



\ 



n 



FIG. 41. FEELERS OF VARIOUS INSTARS OF A WINGLESS VIRGIN 



FEMALE OF Aphis pomi, 



a, new-born ; b, second ; and c, third stages ; d, adult, 

 x 80. After Baker and Turner, Journ. Agric. Res. V. 



moult the number of eye facets is increased and the feeler 

 (Fig. 41 b) has five segments, a short penultimate one being, 

 as it were, intercalated ; and in the third stage (c) this region 

 is divided into two, the full number (six) of the adult being 

 thus attained. At the third stage also small wing-rudiments 



