Insect Galls 
t Leaves of poplar, Populus tremuloides, showing 
numerous globose red-tinted galls from which Mycodiplosis 
populifolia Felt was reared. (Original) 
2 Cyme of elderberry, Sambucus canadensis , show- 
ing several enlarged blossoms infested with maggots of the 
elder flower midge, Youngomyia umbellicola O. S: 
(Original) 
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