12 INSECT-GALLS OF THE VICINITY OF NEW YORK CITY 



17. Oak Spindle Gall {Amphibolips ccelebs Osten Sacken). — Elongated, 

 spindle-shape, soft and green. Contains a kernel held in position by radiating 

 fibers. Length li in. On leaf of red oak {Qiicrcits rubra). Not common. 



18. Acorn Piam Gall {Amphibolips pruniis Walsh). — Globular, somewhat 

 wrinkled or smooth, fleshy but solid; resembles a plum or cherry. About ^ to 

 I in. in diameter. Bright crimson outside, pinkish inside and shading to 

 yellow towards the center. In the center is a single cell in which the larva lives. 

 On cup of acorn of red oak (Qitcrcus rubra). August and September. Some- 

 times rather common. 





19. Homed Knot Oak Gall (.4 ndricus cornigerus Osten Sacken) .—Irregularly 

 globular with many horn-like protuberances through which the gall-flics escape. 

 Very hard and woody. Color of the branch. Inside brown with many larval 



