DISTRIBUTION OF INDIAN FOREST INSECTS 



the Himalayan pines, but two different species of the genus infest the 

 three pines the blue pine, long-leaved pine, and the Pinus khasya of 

 Assam and Upper Burma. 



But whilst such marked limits can be placed upon the distribution 

 and host-plants of many of the coniferous bark-boring pests in the Western 

 Himalaya, the same limits cannot be assigned to the distribution of some 

 of the predaceous pests infesting them. For instance, the clerid Thanasimus 

 himalayensis preys equally upon all the various 

 species of bark- and wood-borers infesting the deodar, 

 spruce, blue pine, and long-leaved pine in the 

 Western Himalaya, appearing equally at home 

 between elevations of 2,500 ft. and 8,000 ft. A 

 Niponius also (N . canalicollis, of the family Histeridae) 

 preys upon the larvae and pupae of these bark- 

 borers, and is to be found not only in the above- 

 enumerated conifers, but also in the Pinus gerardiana 

 in the Suliman Mountains in Baluchistan, where 

 it preys upon the Polygraphus (P. trenchi) which 

 infests the pine in this locality. A curious distribu- FlG 6- 

 tion, since the genus is a Japanese one. canalicollis, Lewis. 



It may be mentioned that another member of 



this genus (N. andrewesi) is to be found preying upon the sal-tree Sphaero- 

 trypes both in the Siwaliks and United Provinces Terai, in the Central 

 Provinces sal areas, and again in Assam, whilst in Coimbatore it attacks the 

 Sphaerotrypes of the Anogeissus. 



Although I would not be understood to say that they do not occur, I 

 have not found the genera Polygraphus and Tomicus in the plains forest, their 

 places being, apparently taken by the genus Sphaerotrypes. 



Per contra, I have not found that the bostrychid genera D moderns 

 and Sinoxylon extend to a great elevation, beyond 4,000 ft. probably, in the 

 Western Himalaya. A species of Sinoxylon has been reported from the 

 Darjeeling district in the Eastern Himalaya, but the locality is not recorded, 

 and the district extends down to the plains. These two genera appear 

 to be particularly addicted to great heat requirements, either dry or 

 moist. 



From the above brief resume of the distribution of a few of the more 

 typical forest pests it will be apparent that it would be difficult to base a 

 distribution of certain groups of insects or of certain families, genera, or 

 species, either upon the species of trees they infest or upon certain classes of 

 mixed forests in which they attack the predominant species and some 

 of those others which are normally found in mixture with it ; for it has 

 been shown that the distribution of the particular insect may extern! far 

 beyond the limits of the predominant tree. Nor is it possible to base 

 distribution, in the light of our present knowledge, on particular /ones >| 

 vegetation, such as a hot dry one, hot moist, etc.; for certain specie^ 



