1 64 A NATURALIST IN THE GREAT LAKES REGION 



FIG. 172. Six typical oak galls (from Felt): a, Spongy oak apple, Amphi- 

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

 flood; d, Oak fig gall, Biorhiza forticornis; e, Woolly stem gall, Callirhytis semi- 

 nator; f, Knot gall, C. punctatus. 



