INSECI> AIIl-.( I IXr; PARK AND WOODLAND TKKES 637 



on S discolor. A smooih, llcsh)-, sessile, s^lobiilar, or sliLjlitly o\.'il 

 monothaiainous i^all, like a iiiiiiialure a|)plc, .3 to. 55 inch (.liaincler, s^row in^f 

 on one side of the midrib of a leaf, and extendini,"- to its edge or be\<>ntl it. 

 The i^rincipal part of the i^^all projects from tiic mulerside of the leaf; verj' 

 rarely it is bisected l)y the leaf. Color or^enish yellow, sometimes with a 

 rosy cheek, es|)ecially th(! upper surface and often with little dots. l'"idl\- 

 mature July 31. An analoffous i^all is formed in Iuiro|)c on various willows 

 by N e m a t u s i^ a 1 1 i c o 1 a W'estw. 



The transformations to the \x:llowish red adidt occur within the ^j;a\\ in 



case of specimens reared by Walsh. There was no earth in the jar and 



some cocoons were spun between the? trails. 



Pontania pisum Walsh. 



Siibs)3lierical, pealike, pale yellowisli galls growing on the underside of the leaves of 

 S a 1 i X discolor are the work of this si)e(ies. 



This i^all-making sawlly is a common species in some sections at least, 

 and on breaking open the hollow galls a whitish, i 8-footed caterpillar with 

 a slightly dusky head and dusky mouth parts ma\' be fountl within. 



The gall has l)een described b\- Walsh as follows : 



A subspherical, pealike, hollow, pale yellowish green gall, alwa\s 

 growing on the underside of the leaf and almost always from one of the 

 side veins (in one case from the midrib) and attached to the leaf by only 

 a minute portion of its surface; .18 to .28 inch in diameter, and a few, 

 immature, only .08 inch in diameter. Almost invariably there is but one 

 gall to the leaf, but on four leaves there were two, and occasionally two 

 are confluent. Surtace in some smooth and even, without pubescence ; in 

 others a little shriveled, generally studdetl in the mediimi sized ones 

 with four to 12 small, robustly conical nijiijles, which in the larger ones 

 have burst into a scabrous brown scar. Only in 3 out of 62 was there any 

 rosy cheek, as in S. p o m u m". The ])oint of attachment is marked on the 

 upper side of the leaf by a brown subhemispherical depression. 



The final transformations to the black yellowish marked adult occur 



in the ground. 



