Plate c. 



Eriophyes sp., (under^surface) Populus 



grandidentata. 

 Eriophyes sp., (upper surface) t Populus 



grandidentata. 



3. Eriophyes sp., Populus treuiuloides. 



4. Eriophyes sp., Tilia Europea. 



5. Eriophyes sp., Betula papyrifera. 



(i. Phloeeoptes aceris, Acer sacchariiium. 



[135] 



