620 NEW YORK STATE MUSEUM 



Small, bladderlike galls on upper surface of soft maple leaves 



Bladder maple gall, K r i o p h y e s q u a d r i p e s, p. 630 



Affectintr linden 

 Sub-globular greenish or whitish galls on both sides of leaf 



Linden wart gall, C e c i d o m y i a v e r r u c i c o 1 a, p. 63 1 

 Top-shaped galls on upper surface of linden leaves 



Linden mite gall, Eriophyes a b n o r m i s, p. 631 



Affecting ash 

 Elongated, greenish or reddish brown galls on the leaf midrib 



Ash midrib gall, Cecidomyia p e 11 e x, p. 632 

 Lobulate green or brown deformed catkins 



Ash flower gall, Eriophyes f r a x i n i f 1 o r a, p. 633 

 Affecting elm 

 Cockscomblike structures on the upper surface of elm leaves 



Cockscomb elm gall, C o 1 o p h a u 1 m i c o 1 a, p. 186 

 Solitary, spindle-shaped galls on the upper surface of red elm leaves 



Red elm leaf gall. Pemphigus u 1 m i f u s u s, p. 633 



Affecting poplar 

 Irregular, subglobular enlargements of the young twigs 



Poplar twig gall, A g r o m y z a a e n e i v e n t r i s, p. 634 

 Folded, convolute masses of foliage 



Vagabond gall. Pemphigus v a g a b u n d u s, p. 635 

 Oval, somewhat elongated galls on the leaf jietioles of cottonwood 



Poplar leaf stem gall. Pemphigus p o p u 1 i - 1 r a n s v e r s u s, p. 635 

 Imperfect, globular galls at base of cottonwood leaves 



Basal leaf gall. Pemphigus p o p u 1 i c a u 1 i s, p. 636 



Affecting willows 

 Galls on slioots 



Fusiform apical galls Willow club gall, Rhabdophaga rigidae, p. 636 



Irregular fusiform enlargements on the young shoots 



European willow gall midge, Rhabdophaga s a li c i s, p. 299 

 Galls on leaves 



Smooth, globular or slightly oval galls like a miniature apple, occur on the leaf midrib 



Willow apple gall, P o n t a n i a p o m u m, p. 636 



Subspheric, pealike, yellowish galls on the underside of willow leaves 



Pontania pisum, p. 637 



