290 [December 



I'ng considered of specific value. The larva of Dataua* ministra, Drury, 

 is described both by Harris and by Fitch as being always vittate with yel- 

 low, and having the superior surface of the first segment yellow. All 

 those that I have myself noticed on the oak, the apple, the wild-thorn, 

 and some other trees were so marked; and so conspicuous is the yellow 

 patch on the first thoracic segment, that Dr. Fitch has appropriately called 

 this larva "the yellow-necked worm." In the year 1861 I found numerous 

 mature specimens of this larva on the hickory, all of which varied from the 

 normal type in being entirely black, with no vestige whatever of any yel- 

 low markings. One of these I preserved in alcohol, and from some of the 

 others I obtained in 1862 2^29 imagos, which differ only from Dr. 

 Fitch's elaborate description of the imago (2nd N- Y. Report, p. 239), and 

 from the colored figure in the new Edition of Harris's Injurious Insects, 

 in being slightly smaller in expanse, (1.45 — 2.00 inch instead of 1.75 — 

 2.50 inch, Harris, and 2.00 — 2.40 inch. Fitch,) and in the fringe of the 

 front wings not being "edged with whitish on the apex." All the larvae 

 that I noticed in 1862 on the hickory were similarly devoid of the yellow 

 marking; and Abbott in his Insects of Geor(jia, (p. 161 quoted in the 

 first edition of Harris's luj. Ins. p. 318,) says that these larvae " besides 

 the leaves of a species of Andromeda also eat the leaves of several kinds 

 of walnut and oak; and that tliose vhich eat ivalnut leaves are always Idack 

 with white hairs, and when their food is of the oak that they are more 

 yellow; but that he had not observed any material difference in the moths." 

 For what reason I do not know, this quotation from Abbott is entirely 

 omitted in the recent edition of Harris's Book, (A. D. 18G2) and prob- 

 ably also from the edition of 1852 edited by Harris himself, of which the 

 edition of 1862 is professedly a reprint with additions from the author's 



MSS. 



In a family like Aphidse, where specific distinctions rest upon so uncer- 

 tain a basis, and are very generally evanescent in the dried specimen, it 

 must be obvious that it is pre-eminently important to carefully search for 

 available generic characters. My own investigations lead me to believe, 

 that generic characters are here correlated with important variations in 

 habits; and that species of the same genus do not sometimes live on the 

 external surface of plants, and sometimes in closed galls or follicles. 



* This insect is referred to Phahena by Drury, to Pygcera by Harris, to Pcfasia 

 (doubtiugly) by Westwood, to Datatia by Walker, and made the type of a new ge- 

 nus. Eumietopoiia, by Fitch, (N. Y. Reports, I. p. 241). Eumetopona should be Eu- 

 mdopa. otherwise it means not "handsome-faced", as its author intended, but 

 •• handsome-faced ass". 



