68 
Indiana University Studies 
detached; the cell covered with a dense, whitish mass of wool which 
dries brown, the wool somewhat flattened, disc-shape, varying in diam- 
eter from 0.7 mm. in one variety to 3.5 mm. in another, averaging 
2.5 mm. Attached to veins on the under surfaces of the leaves; indi- 
cated on the upper surfaces by a smooth, naked, circular, papilla ele- 
vation with a slight indication of a central point, this papilla however 
almost lacking in a couple of varieties. On leaves of white oaks except 
the chestnut oaks (figs. 32, 33). 
RANGE. — Ontario to Minnesota, Florida, and Texas. Apparently 
confined to the eastern half of North America. 
This very common species has developed varieties in which 
the insects are usually distinguishable only by slight differences 
in size, color, and size of the areolet. These differences would 
not be enough to warrant the recognition of distinct groups, 
except that they are very constant in large series represent- 
ing several localities of a single faunal area, and are correlated 
to a large degree with host and distributional data. Never- 
theless in some cases I have not been able to distinguish 
material from undoubtedly distinct faunal areas. The galls 
of the several varieties differ mostly in regard to average 
size. Many of the varieties are confined to single hosts in 
distinct faunal areas ; in a few cases a variety seems to occur 
on two closely related oaks or over two adjacent areas. 
Pulvinus is a variety with a very distinct gall but the insect 
is indistinguishable from opacus. 
The species is closely related to Neuroterus niger which 
is evidently a more primitive species. The degree of separa- 
bility and the distinct form of the gall of verrucarum, its 
restriction to eastern North America, and its exclusion from 
the chestnut oaks, all suggest something of specialization. 
The best key characters for the insect of verrucarum are the 
small abdomen and the slightly and smoothly curved first 
abscissa of the radius; the eyes are smaller and the cheeks 
are wider than in niger. 
The known life history data are much the same for all 
of the varieties. The galls are first seen after mid-summer, 
in August further north, probably earlier further south; the 
larvae do not mature until late in the fall or early in the 
winter, then quickly becoming adults which remain in the 
galls on the dead leaves over winter, emerging in the early 
spring, March or earlier in the south to May further north. 
This is as much as is known of the species, the bisexual form 
