﻿OF THE STATE ENTOMOLOGIST. 93 



immense numbers that disperse through the air to new fields, from a 

 single acre of infected vines, in the course of the late Summer and Fall 

 months. 



If to the above account we add that occasionally individuals aban- 

 don their normal underground habit, and form galls upon the leaves 

 of certain varieties of grape-vine, we have, in a general waj', the 

 whole natural history of the species. 



DIFFERENT FORMS PRESENTED BY THE SPECIES. 



The differences in form and habit which the species presents will 

 be best appreciated by recapitulating them in tabulated lorm : 



1 — The gall-inhabiting type [gallicola — Sixth Kop., Fig. 4,) forming galls on the leaves, 

 and presenting : 



a — The ordinary egg {ibid. Fig. 4, c,) with which the gall is crowded : 

 b — The ordinary larva {ibid, Fig. 4, a, b) : 



c— The swollen, parthenogenetic mother, without tubercles {Ibid, Fig. 4, 

 /, 9-, h) : 

 ^ — The root-inhabiting type {radicicola, Sixth Rep., Fig. '),) forming knots on the roots, 

 and presenting : 



aa — The ordinary egg, differing in nothing from a, except in its slightly larger 

 average size : 

 bb — The ordinary lai'va, also differing in no respect from b : 



d — The parthenogenetic, wingless mother, the analogue of c, but cov- 

 ered with tubercles {ibid, Fig. 5,/, g) : 

 e — The more oval form, destined to become winged {ibid. Fig. 5, e) : 

 /^The pupa, presenting two different appearances {^ibid, Fig. G, e, /, 



and Fig. S, a): 

 g — The winged, parthenogenetic female, also presenting two different 

 appearances {ibid. Fig. 6, g, h, and Fig. S, b) : 

 h — The sexual egg or sac deposited by g, being of two sizes, and giving birth 

 to the true males and females : 

 Z -The male: 

 j — The true female : 

 k — The solitary impregnated egg deposited by j : 



bbb — Tlie larva hatched from /.-, which, so far as known, does not differ 



from the ordinary larva, except in its greater prolificacy: 

 I — The hibernating larva {ibid. Fig. 5 b), which differs only from b in 

 being rougher and darker. 



Thus the insect is found in at least a dozen distinct forms, exclu- 

 ding the variation that some of these forms are subject to ; while, in 

 addition to what we already know of its power to change its habit, I 

 will add that Balbiani reports having succeeded, by gradually accus- 

 toming the species to new conditions, in making the progeny of the 

 root-louse live above ground, where, singularly enough, they did not 



