COUPER ON A GALL-PRODUCING HYMENOPTER. 



445 



1864.] 



as well, becoming, as in many other cases, a double evil, — for this 

 very Eurytoma may some year be produced in such abundance 

 that any of our useful cereals may be destroyed by it. It is 

 different from the barley-straw insect described by Harris in the 

 " New England Farmer," vol. ix, p. 2, as Eurytoma Jiordei. It 

 is larger, and only one insect is found in each gall. As soon as the 



Gall of Triticum repens. 

 a, the hole made by the insect by which it escapes. 



larva issues from the egg, it places its head downwards in the gall, 

 remaining in that position until it eats its way through. About 

 the end of September it ceases to feed, and prepares to meet a 

 Canadian winter (as far as I have investigated its history, it is 

 able to stand a very low temperature). By this time the gall is 

 hardened, and the larvae remain in a torpid state, becoming active 

 again in the following spring, changing to the perfect insect in 



