Callirhytis quercusoperator (Osten Sacken) occurs from New England to North 
Carolina and west to Iowa. It causes the formation of woolly galls on the staminate 
flowers of various oaks. When the adults emerge, they oviposit in immature acorns. 
This results in the formation of so-called acorn pip galls within the acorn cups. In 
heavy infestations, acorn crops are reduced. Callirhytis quercusfutilis (Osten 
Sacken) induces globose, grayish galls up to 11.4 cm long on the main roots of 
young white oaks just below the ground line. 
Neuroterus quercusbatatus (Fitch), the oak potato gall (fig. 203). occurs from 
Ontario and Rhode Island to Florida and west to Illinois on white oaks. There are 
two generations per year. Adults of the first generation emerge in May from galls 
produced on the preceding year’s growth. Second-generation adults emerge from 
green galls. Females of this generation lay their eggs in the same galls from which 
they emerge. 
Neuroterus floccosus (Bassett), the oak flake gall, induces small. hemispherical 
galls from 1.5 to 3.5 mm in diameter on the lower surface of terminal leaves of 
white oaks. These galls are covered with white hairs and often occur in large 
numbers on a single leaf. Heavily infested leaves curl and are unsightly on shade 
trees. 
Neuroterus noxiosus (Bassett), the noxious oak gall, occurs on swamp white 
oaks from New England to Virginia and in the Central States. Heavily infested trees 
may be severely disfigured. 
/ ff 
Courtesy Ill. Nat. Hist. Surv. ~ Courtesy Am. Mus. Nat. Hist. 
Figure 202.—Gouty oak galls caused by Figure 203.—Oak potato gall on white 
Callirhytis quercuspunctata. oak caused by Neuroterus 
guercusbatatus. 
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