Leaf, under side, double chambered conic or depressed (Fig. 5a) gall.
The latter condition is perhaps the more usual. In these forms, the
conic tip is sunken in the central fovea, the gall only measuring from
1½-2 mm. vertical diameter. The conic forms are as though the tip was
pulled out destroying the fovea. These often measure 5 mm. in height.
The width of the galls varies from 3-5 mm. Very light green, or when
older yellow to red, surface roughened with low tubercles as seen
with lens. Inner chamber sub-conic with short mucronate tip. Walls
of both chambers thin and smooth, outer wall slightly sticky. Base
of gall flat, arising from a definite pedicel, resting in a cup-like
depression, which is formed in a definite hyperplasia intercalated
in the leaf. Above, this hyperplasia is evident as a raised circular
area, 2½ mm. diameter, in the center of which is a minute light colored
papilla.
Rather common on _H. alba_. Collected in Hocking and Athens counties,
Ohio.
This double-chambered gall cannot be _Caryomyia inanis_ Felt, for it is
neither “globose and small.” The author describes elsewhere a specimen
which fits that description and is very probably produced by the
cecidozoon just mentioned. Absolute certainty, it must be remembered,
can only be obtained by checking the reared adult insects with the
original descriptions.
Sears described this gall from Cedar Point, Ohio, under the name
_C. inanis_.
Sears, Ohio Nat. 15:380, pl. 18, Fig. 18. 1914.