﻿158 



EIGHTH ANNUAL REPORT 



the progeny from these eggs have, for the most part, failed, I have this year succeeded 

 in hatching them without difficulty, and present a tube with living individuals, and also 

 mounted specimens for the inspection of members, 1 have also succeeded in getting 

 both sexes of the American Oak Phylloxera and in thus completing the natural history 

 of both species. 



Though this true sexual form of vastatrix, from the winged and agamous female, 

 has never before been carefully observed and described, it was nevertheless anticipated 

 by Balbiani in his studies of the European Oak Phylloxera {Phylloxera gicercus Fonsc.) 

 and by myself in my studies of the American Oak species {P. Rileyi).* Balbiani had 

 also obtained what is evidently the same from eggs deposited by wingless, hypogean 

 mothers late in the season and after the winged mothers cease to lly.f 



The winged females carry in the abdomen from three to five and sometimes as 

 many as eight eggs. These eggs are of two sizes — the smaller, which produce males, 

 about three- fourths the size ot the larger, which produce females. As the whole organ- 

 ization of these aerial mothers — with the stout proboscis and ample^wings — indicates, 

 freedom and nourishment are needed to bring the eggs to perfection and cause their 

 proper oviposition. In confinement in small vessels, where these requisites are not 

 easily furnished, the eggs are generally voided, with the death of the parent, on the 

 sides of such vessels ; and those freely laid are with the greatest difficulty brought to 

 the hatching point. Only in two instances did 1 succeed in doing this last year. These 

 failures in the past find their explanation not so much in the difficulty of supplying 

 the natural conditions, as in lack of experience as to what those conditions were. 



"Whether owing to the want of down on the Clinton leaf, or to the fact that the 

 minuteness of the eggs makes it about as difficult to fiad them on a square four feet of 

 earth surface as the proverbial " needle in a haystack," the eggs found on the vine in 

 the aforementioned musUn enclosure were very few compared to the number of winged 

 insects which must have come out of the ground. It was also next to impossible to 



[Fig. 48.] 



Sexed Phylloxer.e : — a, female vastatrix, ventral view, showing egg thvongh transparent skin; 

 b, do, dorsal view; c, greatly enlarged tarsus; d, shrunken anal joints as they aitpear after oviposition; 

 fi, male carycecaulis, dorsal view — the dots in circle indicating natural size. 



* Seventh Mo. Ent. Rep., p. 119. 



t Comptes Rendus de I' Acad des Sc, Pai'is, Nov. 



