THE BIOLOGICAL REVIEW. 73 



ENTOMOLOGY 



CANADIAN GALLS AND THEIR OCCUPANTS. 

 DIPLOSIS THURSTONI, N.S. 



Galls found on the upper half of the stems of Hclianthus 

 ■divaricata, appearing like a swelling of the stem ; symmetrical, 

 varying from ovate to spindle form, the long diameter of gall in 

 the axis of the stem of the plant ; color, the same as stem of 

 plant. The measurements of four galls were, 8x6 mm., 

 diameter of stem below gall 2 ; 15x7 mm., diameter of stem 

 below gall 3 ; 13 x 7 mm., diameter of stem below gall 3 ; 

 23 x 7 mm., diameter of stem below gall, 3. 



The walls of this gall are woody, hard and about 1 mm. in 

 thickness. The interior is filled with a soft, pithdike substance, 

 through which the Diplosis larvae tunnel and on which they 

 feed, and each gall contains from one to ten larvae. 



This is the rarest of the three Heliantlius galls found here. 



One specimen was collected by Mr. Jas. Thurston, April 25, 

 1892, and handed to me ; from this came a $ Torymus, May 

 10, 1893. 



I made a collection of four galls, September 11, 1893, an ^ P ur 

 them in a glass jar in the usual way. On April 18, I opened 

 one of the largest of these galls, and found ten orange-colored 

 cecidomyid larvae. 



May 20, 1894, two producers emerged, and on June 2, two 

 producers and two ^ Torymus. 



The producer of this gall, for which I propose the name 

 D. thurstoni, in -honor of the discoverer, is of the usual Diplosis 

 form and size ; the head and thorax are dark grey ; the 

 abdomen, velvety black, with six white cross bands, interrupted 

 on the dorsum ; the legs are long, and have white annulations. 



The first longitudinal vein of the wing is parallel with the 

 costa, and joins it about its middle, near the angle of an 



