INDIAN FOREST INSECTS 



OF ECONOMIC IMPORTANCE. 



CHAPTER I. 



ON A STUDY OF THE DISTRIBUTION OF THE INSECT 

 FAUNA OF INDIAN FORESTS. 



THE work of investigation into the life histories of the insect pests of the 

 extensive Indian forests, forests covering an area whose climate varies from 

 tropical to sub-arctic, is yet in its pioneer stage. It will be readily under- 

 stood that the character and composition of forests growing under such 

 varied climatic conditions must of necessity differ enormously : from the 

 coniferous and broad-leaved (oak, chestnut, etc.) forests of the Himalaya, 

 through the forests of the hot dry zone, to those of the hot moist, finally 

 merging into the mangrove forests of the seaboard. And this change in 

 the vegetation is accompanied by a difference in the species and genera- 

 in some instances, it may be said, families of the insects which infest the 

 trees growing in a particular area. 



. Gamble has stated * that the Indian forests contain some five thousand 

 different species of trees, shrubs, climbers, and bamboos, covering about 

 one-third of the Indian flora. With this large number of species in the 

 forest to deal with, the investigator into the life histories <>f the insects 

 infesting them would also expect to find, with each change in the forest 

 flora, a corresponding change in the species or group of species of insects 

 infesting the trees of a particular locality. And this, to a certain extent, so 

 far as present investigation work has been taken, has proved to be the case. 

 It is too early yet to draw out a distribution list of the chief important 

 pests of the different classes of forest throughout the countrx, but .1 com- 

 mencement in this direction may be attempted. 



The work of the past decade and a half has made it possible to ^ive 

 broadly the limits within which some of the insect pests of the different 

 kinds of forest commit their depredations, i.e. the area within \\h 

 boundaries their attacks must be leaivd as those of dangerous foes. It 

 will be useful, therefore, as a preliminary to an account of the injurious 

 insects at present known, to glance briefly at the distribution of 3 few of 



* J. S. Gamble, Manual of Indian /'/w/'v/rv, lmn>. p. \\ii. 

 9003 I 1592/10 2000 5/1914 H \ S 



