130 LETTERS TO MR. GIBB [CHAP. xv. 



further notes now. I am sorry not to have acknowledged 

 them and the information in the letter accompanying them 

 sooner, but I had a deal of work, and some temporary 

 difficulty from breaking a blood-vessel in one eye. How- 

 ever I am thankful to say that is all right again. 



I have no doubt you are right about the weather making 

 a most important amount of difference in extent of injury 

 both from Hessian fly and Diamond-back attack. If it had 

 been hot I am afraid Plutella cruciferarum (Diamond-back 

 moth) would have done a deal of mischief. The little 

 Charlock weevil, Ceutorhynchus contractus (see my seven- 

 teenth, 1890, report), has been doing a great deal of mischief 



In usual position, and also with wings expanded magnified ; 

 also natural size. 



FIG. 14. CHARLOCK WEEVIL, CEUTORHYNCHUS COATRACTUS. 



to young turnips at some places on the east side of the 

 country. 



July 30, 1894. 



The V. polychloros specimen came to hand little, if at all, 

 injured by its journey, and in beautiful order for figuring. 

 I am very glad to have it, for besides proving the caterpillars 

 to be of the " great tortoiseshell," 1 had the opportunity of 

 seeing the row of long bristles or stout hairs about a third 

 along the lower part of the front edge (the costa) of the 

 fore-wings. This row of hairs is the structural difference 

 between this " great tortoiseshell," and the "small tortoise- 

 shell " (which is without them), but otherwise the two species 

 are so much alike that there used to be doubts whether they 



