6 INSECT-GALLS OF THE VICINITY OF NEW YORK CITY 



HYMENOPTERA. (Bees, Wasps etc.) 



Family Cynipid^ (Gall-flies). 



The species belonging to this family are small wasp-like 

 insects termed Gall-flies because the majority of the species 

 live within Galls. In the adult Gall-fly, the abdomen is usually 

 much compressed and is joined to the thorax by a short pe- 

 duncle. The wings have comparatively few veins, while some 

 species are wingless. The antennae are not elbowed. They 

 consist of from 13 to 16 joints. The larvge are maggot -like. 



I. Spiny Rose Gall {Rhoditcs bicolor Harr.). — Spherical, covered with 

 many long prickly spines. Yellowish green sometimes tinged with red in 

 summer, and brown in winter. Soft in summer, woody in winter. Diameter 

 I to ^ in. On twigs of wild roses. Rather common. 



2. Rose Root Gall (Rhoditcs radicum Osten Sacken). — Irregularly rounded, 

 with a deep impression above and below at place of attachment. Smooth, 

 reddish brown. Pithy in substance, containing numerous cells. Length i \ to 

 2 m. At roots of the wild roses. Not common. 



