﻿OP THE STATE ENTOMOLOGIST. 119 



of the congeneric Grape species. Undergoing- all its ciianges above ground, the evolu- 

 tion of the Oak Phylloxera is much more easily studied than is that of the Grape Phyl- 

 loxera ; and I have had better fortune in obtaining the sexual individuals from the 

 winged females, though the few specimens mounted so as to be of any value for descrip- 

 tion, are all males. These beings are so excessively minute that their study is attended 

 with many difficulties, unless one can devote more time to it than has been at my dis- 

 posal ; yet, with the exception of the description of the true female, its natural history 

 may now be considered complete ; while the thorough observations of Balbiani on the 

 closely allied European Phylloxera quercus'^¥o\\?,c., will supply inferentially the miss- 

 ing data. We saw last year that the American Oak Phylloxera hibernates in the larva 

 state attached to the twigs. " As the leaves begin to put forth, our young Oak Phyl- 

 loxera cast off their Winter skin, and tlieir lethargy with it. They niay then be seen 

 crawling up and down the twigs, but do not settle on the leaves. Attaining, in a few 

 days, full growth, they begin a virginal reproduction by covering the twigs with eggs, 

 which hatch in just about a week if the weather is warm and propitious. Thus the 

 [Fig. '2'2.] hibernating lice acquire their growth, and give birth to the first 



"V^ //" generation, in the short space intervening between the opening of 



^^-^^^^^^^ /^ the buds and the full growth of the first leaves."— [eth Eeport, 

 p. 65. This first generation, which is sufficiently numerous, 

 as the hibernating mothers are very prolific, disperses over the 

 leaves,[and one generation of parthenogenetic wingless females, 

 follows another till the fifth or sixth, when, from the middle to 

 the end of July, the winged females begin to appear. There is the 

 \^/^ x>X same diminution in fecundity, until the appearance of the winged 

 [J cc c,:^» individuals that has been observed by Balbiani in the European 

 ^ quercus ; and the winged females, just as in the other species, bear 

 showlu'-^^KwfitHT ^01"^^^^ ^"'y ^ ^^^ ^^&' ^^ *^^^ sizes, which give birth to the sexual Indi- 

 es) and tarsus (c) ; tiieyiduals. These pair and the female lays the solitary e^s, which 



dot at side showing iiat- ^ ^ <-^<^ 



oral size. gives birth to the normal parthenogenetic mother, which hiber- 



nates as a larva. The variation to which the species is subject ; or rather the diflerent 

 forms which it presents, will be appreciated by the scientific reader from the following 

 specific diagnosis : 



SPECIFIC DIAGNOSIS OF rilYLLOXERA RILEYI Liclitii 

 Apterous, agamous ; normal form (a) : — 



Length, 0.01(5 inch, or rather more than l-;i as large as vastatrix, with which it agrees in 

 color. Proportionally more slender, with the abdomen more tapering. Body insected and 

 covered with tuliercles very much as in wingless radicicola form of vastatrix, but with an addi- 

 tional pair on the head, and those on the seventh abdominal joint always distinct. These 

 tubercles concolorous with the body, fleshy, more or less elongate — from 1-12— 1-G the veidth of 

 middle body— and surmounted at tip with a short, dark hair. The anterior tubercles longest ; 

 the lateral outline showing a series of thirty-six such tubercles, nearly equidistant, springing 

 at about right angles from surface. The intermediate dark points, on thoracic insections, also 

 as in vastatrix. Antennie precisely as in Vfls/a//('a.'. Legs with the ends of tibirc more swollen, 

 and the claws more prominent. Venter, with a dusty tubercle just inside each coxa. 



* There is some confusion as to what should really be considered the quercus of Fonscolombe, and 

 Signoret, Balbiani and Lichtenstein have each in turn recentlj' endeavored to define the European spe- 

 cies. Signoiet Avould reduce them all to three (Coinptcs Rendus, Dec. 7, IST-t) , as follows : 1. Ph. 

 quercus Fonac. =Balbianii Lichtn.=coccj«e(i Balb. 2. Ph. coccinea K{i\t.=quercus {Sign. )=^coccinea 

 Hayden. 3. Ph. corticalis Kiilt.=Lichtensteinii Ba.\b.=RileijiLiichtn. Lichtenstein, on the contrary, 

 makes four species (ifijf/', Feb. 8, 1S7.">) , as follows: 1. Ph. quercus ¥oi\sc. ^coccinea Uajden. 2. Ph. 

 Rileyi Lic\\tn.=corticalis Ko\\i\r,-=Lichtensteinii Biilb. 3. Ph. Balbianiiljicht. 4. Ph. acanthochcrmes 

 Kollar .=sf M/f/ejo. Sign . In either event the genus is much more poorly represented there than in Americ.i. 

 I would remark here also that I very much doubt whether our American Oak species occurs in Europe, 

 however closely the corticalis, which diflers in habit, may ic^cmble it in appearance. 



