66o 



British Crops of 1908. 



[dec, 



young trees, it will be necessary to take active measures against 

 them, but unless this occurs, in view of the great assistance 

 derived from their presence in combating the saw-fly, it would 

 be advisable neither to destroy nor encourage them. 



In districts where the attack of the saw-fly is pronounced 

 it would be well to postpone the planting of young larch trees, 

 unless some remedial measures such as have been suggested 

 can be carried out. If the land cannot be spared another 

 species of conifer might be planted, as N. erichsoni strictly 

 confines its attention to the larch. 



If the natural means of control, such as birds, are encouraged, 

 and it is upon these and the parasites that the extermination 

 of the pest chiefly depends, the attack will last for a much 

 shorter length of time, and there will ultimately be a less 

 pecuniary loss than if a policy of laisser faire be adopted. 



Description of Figures. 



Fig. 1. — The Small Field Vole, Microlus agrestis, which leeds largely on the 

 larvae of the saw-fly during the winter months. (Three-quarters 

 natural size.) 



,, 2. — Cocoons of Nematus erichsonz, from which the larvae have been extracted 



by the Field Vole. The teeth-marks are distinctly visible on many of 



the cocoons shown. (Natural size.) 

 ,, 3. — Dead terminal shoots of larch, showing characteristic curled appearance, 



caused by the wounding of the stem by the female saw-flies in depositing 



their eggs. 



,, 4. — Mesoleius aulicus, Grav. An Ichneumon parasite of the larch saw-fly. 

 Three times natural size, which is shown by the cross-lines. 



I am indebted to Ur. O. V. Darbishire for photographing Figs. I and 2. 



THE BRITISH CROPS OF 1908. 



The preliminary statement of the estimated yield of the cereal, 

 pulse, and hay crops in 1908 was issued on the 6th November 

 and that relating to the potato and root crops on the 

 23rd November last. The average yield per acre of each of 

 these crops is given in the following table, which also shows 

 the difference from the result recorded last year, and from the 

 average of the ten years 1898-1907. 



