THE GRAPE PHYLLOXERA. g 



Type Radicicola or Root-inhabiting. — We have seen that, in all 

 probability, gallmcola exists only in the apterous, shagreened, noii- 

 tubercled, fecund female form. EacUcicola, however, presents itself 

 in two principal forms. The newly-hatched larvse of this type are un- 

 distincjuishable, in all essential characters, from those hatched in the 

 galls ; but in due time they shed the smooth larval skin, and acquire 

 raised warts or tubercles which at once distinguish them from gallmcola. 

 In the development from this point two forms are separable with suffi- 

 cient ease, one (a) of a more dingy greenish-yellow, with more swollen 

 fore-body, and more tapering abdomen; the other (/3) of a brighter 

 yellow, with the lateral outline more perfectly oval, and with the abdo- 

 men more truncated at tip. 



Fig. 4. 



Type Radicicola — «, roots of Clinton vine, showini; relation of swellincrs to leaf-galls, and power 

 of resisting decomposition; 5, larva as it appears when hibernating; c, d^ antenna and leg of 



^ decomposition; 6, larva as it appears 

 same; e,/, g^ forms of more mature lice. 



The first or mother form (Fig. 4,/, g) is the analogue oi gallmcola, 

 as it never acquires wings, and is occupied, from adolescence till death, 

 with the laying of eggs, which are less numerous and somewhat larger 

 than those found in the galls. I have counted in the spring as many 

 as 265 eggs in a single cluster, and all evidently from one mother, who 

 was yet very plump and still occupied in laying. As a rule, however, 

 they are less numerous. With pregnancy this form becomes quite 

 tumid and more or less pyriform, and is content to remain with 

 scarcely any motions in the more secluded parts of the roots, such as 

 the creases, sutures, and depressions, which the knots afford. The 

 skin is distinctly shagreened (Fig. 4, /i), as in gallmcola. The warts, 

 though usually quite visible with a good lens, are at other times more 

 or less obsolete, especially on the abdomen. The eyes, which were 

 quite perfect in the larva, become more simple with each moult, until 

 they consist, as in gallmcola^ of but triple eyelets (Fig. 4, Jc), and, in 

 the general structure, this form becomes more degraded with maturity, 



