OF THE STATE ENTOMOLOGIST. 



41 



the winged insects obtain in the other species of the genus that are 

 known, and have always been lool^ed upon as sexual. Signoret, an au- 

 thority on these insects, once so looked upon them, (10) but has lately 

 declared the shorter form to be a female emptied of her eggs. If this 

 be so, then the eggs must be laid before the insect arrives at maturity 

 (a highly improbable circumstance) ; for the characteristics which dis- 

 tinguish it are to be noticed in the pupa (Fig. 8, a), which is almost as 

 broad as long, with very large wing-pads and strong limbs ; while the 

 winged insect does not, as we have seen, carry any eggs. But, what- 

 ever the true nature and functions of these problematic or gynan- 

 drous individuals, it would seem, from some exceedingly interesting 

 observations lately made by Balbiani,* that they can not be males, if 

 there be any such thing as unity of habit and character among the 

 species of the genus. Balbiani has made the curious discovery, in 

 the annual development of Phylloxera qiiercus^ that the winged indi- 

 viduals, which appear in August, fly off to new leaves and deposit 

 t*''^' '"^ •] their unimpregnated eggs, to 



the number of five to eight. 

 These eggs ore of two differ- 

 ent sizes, the smaller being 

 readily separated from the 

 larger. They hatch in about 

 a dozen days, the smaller giv- 

 ing birth to males, and the 

 larger to females, which have 

 neither mouth-parts nor di- 

 gestive organs, and neither 

 grow nor molt after birth. 

 The sole aim of their exist- 

 ence is the reproduction of 



Type Radicicola:—*?, 6, pupa and imago of a problematic the SpeCieS, and they Crawl 

 ijidividual, or .'^upposeLl male; c, d, its auteniui aud .. i , , , ,i 



leg; e, vesicles fouud in abdomeu. actively about and gather in 



little multitudes in the crevices and interstices which are afforded 

 them. Tfie male, except in size, seems to differ from the female only 

 in having a small conical tubercle, which serves as sexual organ. 

 Coitus lasts but a few minutes, and the same male may serve several 

 females. Four or five days after birth the female lays a solitary egg, 

 which, increasing somewhat after impregnation, had caused her abdo- 



* Compter Rcndiis del' Academic des Sciences, Pariij, 1873, p. 884. 



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