“Rounded, irregular, hard swelling on the under side of the hickory
leaf, on the mid-rib near the base of the leaf about half an inch long.
In July, pale yellowish and contained in several small hollows, minute
whitish larvæ, with breast bone narrowed anteriorly and ending in a
point.” Osten Sacken.
This form is so different from the other itonid galls of the hickory
that the writer is inclined to place it here tentatively. It is very
similar to _Phylloxera caryævenæ_ Fitch, with the exception that the
hyperplasia extends below the leaf, while in the phylloxera gall it is
developed on the upper side. The writer has observed orange colored
larvæ in the aphid galls, but they were not definitely determined to be
itonid.
Since this type of gall has not since been reported as definitely
caused by itonid larvæ, it is barely possible that Osten Sacken
described the empty phylloxera gall above mentioned containing
inquilinous itonid larvæ. The writer found many of these galls deserted
by the aphids in the middle of July and Pergande states that the aphid
nymphs begin to leave the galls in July. At this time, these galls
are a “pale yellow” color as described for the “cynipsea” gall. The
writer’s observations were made in southern Ohio, while Osten Sacken’s
were made in the vicinity of Washington, D. C.
Osten Sacken, Lowe’s Monogr. Dipt. N. Am. Pt. 1. p. 193. 1862.