INSECT-GALLS OF THE VICINITY OF NEW YORK CITY 35 



77. Hackberry Nodule Gall {Pachypsylla cdtidis-gcmma Riley). — Variable in 

 size and in shape. Bud-like and looking as if formed by the agglomeration of a 

 number of rovmded nodules. Hard and woody, with a number of cells inside. 

 On branches of hackberry {Celtis occidcntalis). It is a deformation of the 

 young bud. Common. 



78. Hackberry Blister Gall {Pachypsylla celtidis-vesictilum Riley). — Circu- 

 lar, flat and blister-like. Convex on the tmder side with a small nipple in 

 the middle. Green. In numbers on leaf of hackberry {Celtis occidcntalis). 

 Common. 



79. Hackberry Nipple Gall {Pachypsylla celtidis-mamma Riley). — Repre- 



