42 SIXTH ANNUAL REPORT 



men to swell and enlarge a little prior to oviposition. Two or three 

 days after this operation the mother dies ; but the males live as long 

 again. 



This solitary egg, which Balbiani calls the winter egg, soon takes 

 on a dark color, which indicates its fecundity and distinguishes it from 

 parthenogenetic eggs of both the winged and wingless females. It is 

 surmised that this egg passes the winter to give birth in spring to the 

 form destined to recommence the cycle of development belonging to 

 the species. 



These discoveries are truly remarkable, and appear to me all the 

 more so since Balbiani* likewise found that the individuals which 

 never become winged attain maturity without laying eggs on the 

 leaves on which they were born, but crawl on to the branches and in 

 the interstices of the old scales at the base of the new year's growth. 

 There they lay a number of eggs, vjhich are ahsolutely lihe those de- 

 posited hy the wwged females, and, like them, produce the sexual 

 individuals: i. e., hoth males and females. Now, this does not corre- 

 spond with what I have seen myself of the species, or with what has 

 been described by others; for the apterous individuals o? querous sur- 

 round themselves with eggs on the leaves where they are born. 



M. Maxime Cornu has already announced having found a sexual in- 

 dividual, without mouth-parts, of the Grape Phylloxera; and it is quite 

 likely, now that Balbiani has paved the way, that we shall next year 

 have its natural history complete. But whether the Grape Phylloxera 

 produces this fecundated and solitary egg or not, such an egg is neither 

 essential to its winter life, nor to that of an American species (Phyl- 

 loxera Rileyi Lichtenstein), which will be described further on, and 

 which is, in every respect, very closely allied to the European quercuu. 



While, therefore, there is yet much to learn in the life-history of our 

 Grape Phylloxera, the facts which I have already unequivocally stated, 

 as well as those which I shall now proceed to give, remain indispu- 

 table, and do not seem fully to accord with Balbiani's discoveries. 



As fall advances the winged individuals become more and more 

 scarce, and as winter sets in only eggs, newly-hatched larva^, and a 

 few apterous egg-bearing mothers, are seen. These last die and dis- 

 appear during the winter, which is mostly passed in the larva state, 

 with here and there a few eggs. The larv£e thus hibernating (Fig. 5, h) 

 become dingy, with the body and limbs more shagreened and the claws 

 and digituli less perfect than when first hatched ; and, of thousands 

 examined, all bear the same appearance, and all are furnished with 

 strong suckers. As soon as the ground thaws and the sap starts in the 



* Auctore Dr. Fr. Ciiziilis, si.-t rf|)oi-ti'il in tlic Message)- da Midi, November 10, 1873. 



