1 64 A NATURALIST IN THE GREAT LAKES REGION 



Fig. 172. — Six typical oak galls (from Felt): a, Spong>' oak apple, Amphi- 

 bolips confluentus; b, Hollow oak apple, A. inanis; c, Woolly leaf gall, Ajidricus 

 flocci; d, Oak fig gall, Biorhiza forticoniis;. e, Woolly stem gall, Callirhytis setni- 

 nator; /, Knot gall, C. punctatus. 



