ON METHODS OF PREVENTING INSECT ATTACK 41 



season closes at the end of March in the plains the beetles bred out of 

 the felled trees must seek standing diseased trees in the forest or wind- 

 falls in which to oviposit, and failing such must infest green trees ; for 

 fresh living bast and sapwood is a necessity for their larvae, which 

 can neither live nor find sustenance save in sappy fresh bast and sap- 

 wood. 



The point of the argument is, then, that though at present the number 

 of beetles breeding in the tops of felled trees cannot be prevented, in the 

 plains at any rate, it would be advisable to insert a clause in the felling 

 contractor's agreement making it imperative that the trees he fells should be 

 at once barked. Such a clause would do a great deal towards keeping down 

 some of the most serious of the pests of the trees. 



In the coniferous forests, where the danger from bark beetles is far 

 greater than in the broad-leaved areas, the thicker branches of the tops 

 should also be barked, and wherever possible the tops should be burnt or at 

 least have the outer bark carbonized so as to render it unpalatable to bark 

 beetles. 



(4) Fires. — The danger to be feared from fire running through a forest 

 is due to the fact that a number of trees, the number depending upon the 

 intensity of the fire, are liable to become weakened in health and thus to 

 lose vitality. In this state they afford suitable material for the oviposition 

 purposes of bast- and wood-feeding beetles, and, under the attacks of 

 these, trees which might otherwise have recovered in time, finally suc- 

 cumb and die. The danger from fires overrunning a forest, so far as 

 subsequent insect attack goes, is greater in coniferous forests than in broad- 

 leaved ones. 



Present observations would seem to indicate that fires in deodar, blue- 

 pine, or spruce forests in the Western Himalaya are, if the trees are at all 

 scorched, almost invariably followed by an attack of the deodar Scolytu^ 

 beetles, and the spruce and blue-pine Tomicus and PolygrapJms. In the Pimis 

 longifoUa areas the fires which sweep over considerable tracts of the Kumaun 

 district forests have led to the trees being seriously attacked in parts by the 

 Cryptorhynchus weevil, the Capnodis and Anthaxia buprestids, the Nothorrhina 

 longicorn, and the Tomicus and Polygraphns bark beetles. 



After a fire has occurred in a coniferous area in the Himalaya the 

 closest scrutiny should be kept on the trees during the following two years, 

 and those seen to be infested with bark beetles should be cut out, cut up, 

 and the bark burnt. 



Similarly, when a severe fire has run through an area of young sal-tree 

 growth, trees whose vitality has been much lowered will be infested by the 

 Sphacrotrypes bark beetles. 



The timber of trees dying or newly killed by fire is at once infested 

 by Sinoxylon and other wood-borers ; sissu, sal, Tenninalia, Pterocarpus, 

 etc., being liable to such attack. 



