Callirhytis cornigera (O. 8.), the horned oak gall, occurs from 
southern Canada to Georgia and Iowa. It produces galls on the 
twigs of pin, scrub, black, blackjack, and water oaks. Injurious 
infestations have been observed on roadside and woodland oaks 
in the Niagara area of Canada. 
Calliirhytis (=Andricus) gemmaria (Ashm.), the ribbed bud 
gall, occurs from Massachusetts to Florida, Illinois, and Texas. It 
produces somewhat conical, strongly ribbed galls about 5 mm. 
long on the twigs of black oaks. These galls sometimes occur in 
such large numbers as to cause infested twigs to split and die. 
Entire young trees are sometimes killed. 
Callirhytis operator (O. 8S.) occurs from New England to Vir- 
ginia and Texas and 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. C. futilis (O. 8.) produces globose, 
grayish galls up to 414 inches long on the main roots of young 
white oaks just below the ground line. 
Neuroterus quercusbatatus (=batatus) (Fitch), the oak potato 
gall (fig. 197), occurs from Ontario and Rhode Island to Florida 
F-520107 
FIGURE 195.—Heavy infesta- 
tion of galls on twigs of 
Nuttall oak in the Missis- 
sippi River Delta region. 
480 
