1906 ENTOMOLOGICAL SOCIETY. 71 



the middle of the under side of the galL Hypertrophy polythalamous. 

 Larval chambers about 1-2 m.m. in diameter. It is found on the upper side 

 of the leaf. Occurs on White Oak (Quercus alha). Common. 



Furry Ball Gall on Oak {Neitrotus floccosus). 

 This is a small spherical gall about 3 m.m. in diameter, which occurs 

 on White Oak on the veins of the leaves upon the under side of the leaf. 

 The gall is thickly covered with fine short hair which forms a cushion all 

 round it. The gall is rather hard, and in the centre of it is a very small 

 thick-walled shell about .25 m.m. in diameter. Occurs on White Oak (Quer- 

 cus alba). Not common. 



Pointed Bullet Gall on Oak (Holcaspis duricaria). 



A spherical ball-like gall produced upon the stem of White Oak and 

 Burr Oak. A short point at the apex of the gall distinguishes this species 

 from globulus. Hard and woody, with a small cavity in the centre, con- 

 taining a small, oval monothalamous, thin-walled, larval chamber. Oc- 

 curs on Burr Oak (Quercus macrocarpa). Common. 



Little Oak Apple (Andricus palustris). 



This gall is produced by a malformation of the leaf blade, nearly al- 

 ways at the outer edge. It is a spherical, monothalamous, hollow ball, pro- 

 jecting from both sides of the leaf. It is from .9-1 cm. in diameter and 

 comparatively thin-walled. The interior cavity is lined with smooth tissue 

 and contains only a small thin-walled ball which rolls about freely in the 

 gall. The single chamber of this ball contains a small larva. This hall is 

 about 2 m.m. in diameter. The insect emerges, through a small hole cut in 

 the side of it, in May. The gall is green or green and red. Occurs upon 

 the leaves of Pin Oak (Quercus palustris). Not common. 



Oak Midrib Gall (Andricus piger). 



This gall is an irregular, woody swelling of the midrib of Burr Oak. 

 It averages about 7/8 inches in length, and about 5/8 inches in diameter. 

 Externally it is green, glabrous or slightly pubescent and projecting on 

 both sides of the leaf. Internally it is dense and somewhat woody in struc- 

 ture, and containing numerous small cells about .5 m.m. in diameter, sur- 

 rounding each of which is a layer of harder tissue. These are the larval 

 cells. The gall-flies escape early in June through holes cut through the 

 gall. Occurs upon leaves of Burr Oak (Quercus mucrocarpa) . Common. 



Furry Ball Gall on Oak (Andricus lana). 



This gall is produced upon the midrib upon the under side of the leaf 

 of the Burr Oak. It is a white, furry, hemispherical mass, varying from 

 4-11 m.m. in diameter. This is composed of innumerable fine, woody fibres 

 to which are attached small round kernels, in each of which is a minute 

 white larva. These kernels are attached to the midrib of the leaf. Occurs 

 upon leaves of Burr Oak (Quercus Tnacrocarpa) . Not common. 



Willow Apple Gall (Pontania pomum). 



A smooth, fleshy, sessile, globular or slightly oval monothalamous gall, 

 like a miniature apple. About 1 cm. in diameter, growing on one side of 

 the midrib of the leaf and extending to its edge or beyond it. The principal 

 part of the gall projects from the underside of the leaf. Color greenish yel- 

 low, often with a rosy cheek. Mature about Tuly 31st. Occurs on many 

 species of scrub willows (Salix sp.) Common. 



