PLATE XL Aphid Galls. 



i. Mordwilkoja vagabundus Walsh, — vagabond poplar gall, x I, 



2. Pemphigus populicaulis Fitch, x I. 



3. Hamamclisfes spinosus Shimer, x 1. 



4. Hormaphis hamamelidis Fitch, x 1. 



5. Phylloxera caryaecaulis Fitch, — hickory aphid gall, x 1. 



6. Chermes cooleyi Gillette, x 1. 



7. Chermes abietis Linnaeus, — spruce aphid gall, x 1. 



Photographs by B. H. Walden. 



