ON THE LIFE HISTORIES OF FOREST INSECTS 23 



instances proved all too true. But it must be remembered that the 

 study of the insect pests of the Indian forests is still in the pioneer 

 stage. Some considerable collections of forest insects — minute insects as 

 many of our tree pests are — were forwarded to the British Museum in 

 igoi. The answer came back that a large percentage of the species 

 appeared new to the Museum collections. Several of them are still without 

 a specific name. Investigation work and collection work carried out since 

 then has tended to show that the insect fauna of our forests, or perhaps it 

 would be more correct to say the insect fauna of our trees, is practically a 

 new field of research, a field as interesting as it is arduous. So far as has 

 been ascertained, a considerable proportion of the species of importance to 

 the forester have yet to be described ; and such descriptions, depending, as 

 they must do, upon the convenience of the savants who devote their life's 

 work to the particular family or group to which they belong, must be 

 awaited with patience. This does not, however, prevent our endeavouring 

 to ascertain the life histories of these insects in the forest, and to find out 

 exactly how they affect the forest officer. There are at the present moment 

 several examples of pests whose life histories are more or less completely 

 known, but which still await a specific name. This, however, is also the 

 case with some of our less well-known forest trees. 



It is not, perhaps, surprising that so many of the insects living in 

 and affecting the growth or destroying the trees of the Indian forests 

 should have remained up till now unknown, since it may be taken as a 

 general rule that — 



(i) Many of the insects whose grubs feed in the bast or wood of trees 

 are nocturnal and usually only appear upon the wing at night, when 

 they leave the trees on maturing, and then for only a comparatively 

 short period, from a few hours to a week or two at most. Many Ceram- 

 bycidae and Scolytidae only leave the trees in w^hich they were reared at 

 night, and then fly off in search of recently felled trees or sickly standing 

 trees, where they pair either outside the tree or after they have tunnelled 

 into it. If they pair outside the tree they hide during the daytime in the 

 shade of felled trees on the surface of the bark nearest the ground; or 

 they hide in the thick scrub jungle or beneath pieces of bark, stones, or 

 other refuse on the floor of the forest daring the daytime, and lay their 

 eggs in the crevices of the bark of sickly standing trees at night. As these 

 insects do not appear naturally on the wing during the daytime they 

 have not been caught by ordinary collectors, and so have not reached 

 European collections in the manner in which many of the insects of 

 the non-afforested areas have. 



(2) Many of the worst pests of the trees of the forest are minute 

 inconspicuous insects which have remained uncollected, and so unnamed 

 up to date. The family Scolytidae, containing large numbers of tiny insects 

 very difficult of classification, and yet of the very greatest importance to 

 the well-being of the Indian forests, is a case in point. 



