620 



NEW YORK STATE MUSEUM 



Small, bladderlike galls on upper surface of soft maple leaves 



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



Affecting linden 

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



Linden wart gall, Cecidomyia v e r r u c"i c o 1 a, p. 631 

 Top-shaped galls on upper surface of linden leaves 



Linden mite gall, Eriophyes abnormis, p. 631 



A ffecting ash 



Elongated, greenish or reddish brown galls on the leaf midrib 



Ash midrib gall, Cecidomyia pell ex, 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, Colopha ulmicola, 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, Agromyza aeneiventris, p. 634 

 Folded, convolute masses of foliage 



Vagabond gall, Pemphigus vagabundus, p. 635 

 Oval, somewhat elongated galls on the leaf petioles of cottonwood 



Poplar leaf stem gall, Pemphigus populi-transversus, p. 635 

 Imperfect, globular galls at base of cottonwood leaves 



Basal leaf gall, Pemphigus-populicaulis, p. 636 



Affecting willows 



Galls on shoots 



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



Irregular fusiform enlargements on the young shoots 



European willow gall midge, Rhabdophaga s a 1 i c i s, p. 299 



Galls on leaves t 



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



Willow apple gall, Pontania p o m u m, p. 636 

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



Pontania p i s u m, p. 637 



