1891.] EEL-WORMS AND INSECT DIAGRAMS 209 



about it, but it has been a long, severe labour, and I tho- 

 roughly believe that on the adoption of the arsenical 

 insecticides depends the success of the English orchard 

 growing in the future. 



So far as I see, the " grubs " have not been the least the 

 worse for the cold of the recent frost so long as they were in 

 their self-made shelters below ground, but we carried devas- 

 tation amongst hundreds of Cockchafer grubs, Melolontha 

 vulgaris, by ploughing. The larvae were too torpid to bury 

 themselves, and the birds disposed of them very thoroughly. 



Dr. Lindeman writes that he "had a district inspection 

 set on foot " to find presence of Tylenchus devastatrix in 



i, Adults ; 2, anterior of female, showing mouth- 

 spear ; 3, embryo in egg all greatly magnified, 

 anterior portion 440 times (from figures by Dr. J. 

 Ritzema Bos). One of the causes of clover-sickness. 



Tulip-rooted " 

 oat plant. 



FIG. 47. STEM EEL-WORMS, TYLENCHUS DEVASTATRIX. 



Russia, but "always with negative results." This is very 

 interesting. 



June 26, 1891. 



Did I tell you that my sister has been preparing a set of 

 twenty-four diagrams same size and in the same style as 

 that of the Hessian fly ? These are of our most destructive 

 or most remarkable insect pests and our Royal Agricultural 

 Society has approved so highly of those which are printed 

 that they have arranged for her to transfer to them the 

 ownership of copyright of the set. This gratifies her very 



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