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Fig. 52. P. poputiconduplifoliiis. Galls collected at Orono, July 15, 1912. 

 Fig. 53. P. gravicornis. Galls collected at Orono, July 7, 1911. 



Fig. 54. Melanoxanthe7'iu7n salicis. Collection made at Orono, May 16, 

 1910. Fig. 55. Aphis populifoliae. Collection made at Veazie, July 18, 1912. 



