Paet I.] Stebbtng : Insect Pests of the Himalayan OaJcs. 13 
feed upon. Consequently barking the trees soon after felling will ensure 
the destruction of the XylotrecJi us beetles since their grubs spend the whole 
of the period of their existence in this stage in the bast layer and outer 
sap wood. The barking of the trees leads to the drying up of 
the bark and the death of the grubs. To make certain of protecting oak 
timber against the attacks of the oak timber longicorn borer it is 
absolutely essential that the tree should be barked as early as possible 
after felling in order to ensure that the ffrub does not g'et down into the 
sap wood to such a depth that the barking of the tree would have no 
harmful effects on it. Once it has got there the barking of the tree 
will not prevent the larva from making its destructive galleries in the 
heart wood of the tree and thus ruining the timber. 
Points in the Life Histories of the Xylotrechus Beetles requiring further observations. 
1. Where and when the eggs are laid. Is it on the bark in July, 
August ? 
2. How long the larva spends in the larval stage. 
3. Length of the pupal stage. 
4. The number of generations in the year. 
