40 INDIAiN FOREST INSECTS 



pine, and these merely served as death traps for the deodar. At Pajidhar 

 in Jaunsar I saw a small plantation of young deodar entirely killed by this 

 overflow of the Polygrapiius from the already fully occupied blue pine. In 

 the same way if the casuarina of the East Coast plantations is mixed 

 with another species of tree to minimize the attacks of the Arbela cater- 

 pillar, care must be taken that a species is chosen which is not itself 

 attacked by the caterpillar. For Mr. C. E. C. Fischer has shown that 

 the larva feeds on the bark of a number of trees in addition to that of 

 the casuarina. 



(3) Felling Operations. — Properly regulated forest management ordains 

 that the forest shall be kept free of all dying trees, dead material, tops and 

 windfalls, etc. In the large areas which fall to the charge of the executive 

 officer in India this ideal is not at present a possibility. Something more 

 might, however, be attempted than is at present usually the case. The annual 

 felling operations as undertaken throughout the country are a direct source 

 of assistance to the insect pests of the forest. The difficulty in dealing with 

 the tops, an enormous mass of branch wood, is at present in many instances 

 an insuperable one over large areas where the management is on the 

 selection system. The same difficulty does not, however, apply to the boles 

 of the felled trees, which often lie in the forest from two to three months 

 after felling before being finally cut up and removed. In these boles thus 

 left unbarked incredible numbers of bark-boring beetles are bred. To quote 

 a few instances. In Jaunsar I calculated in igo2 that the trunk of a large 

 felled deodar go ft. in length from base of butt to the first branch 

 (diameter, 3 ft. at base and 10 in. at top) gave rise to 54,000 beetles, 

 allowing for casualties. 



Again, whilst in the Goalpara forests with Mr. Perree it was proved 

 beyond question that the larvae of the longicorn Hoplocerambyx spinicornis, 

 which lays its eggs in crevices of the bark of newly felled or dying standing 

 sal-trees, get down into the sapwood of the bole within a week of hatching 

 out, and that barking subsequently to this will not save the timber of that 

 bole from being riddled and ruined by the large tunnels of this pest. In 

 this case not only does the felled tree breed up future beetles, but at the 

 same time the timber itself is ruined. In a perhaps lesser degree this 

 is true in the sal areas of the United Provinces Terai and Central Pro- 

 vinces. The same tree if left unbarked after felling breeds out thousands of 

 the bark beetles of the genus Sphacrotrypcs, a species of which infests the 

 sal of the United Provinces Terai, the Central Provinces, and Assam. In 

 fact, there is no tree in India subject to the attacks of bark beetles which 

 if felled and left unbarked in the forest for a couple of months but gives 

 a home to thousands of maturing beetles which on leaving it search for 

 other similar felled trees or standing sickly ones in which to oviposit. For 

 it must be borne in mind that these bark beetles pass through from three 

 to five generations or life-cycles in the year. Consequently when the felling 



