DISTRIBUTION OF INDIAN FOREST INSECTS 



Fig 



;. — Splieiioptcra ati'i'/iiiui, Kerrem. 

 tf I natural size, d e enlarged. 



Serious pests, small in si2e, there 



differs greatly from that in the Eastern portions of the range. And this 

 is only what might be expected, since the composition of the forest in the two 

 localities is entirely different. In the Western Himalaya, as compared with 

 the broad-leaved assemblage 

 of species characteristic of 

 the Eastern, the coniferous 

 forests predominate, and we 

 find classes of pests more 

 resembling those of the 

 European, American, or 

 Japanese coniferous areas. 

 Here again anomalies are 

 found in the distribution of 

 genera and species, and 

 even families. The impor- 

 tance of the families Bos- 

 trychidae, Buprestidae, and 

 Cerambycidae, all powerful 

 groups in the plains, has disappeared, 

 are in the two latter families, as witness the deodar buprestid Sphenopteni 

 aterrinia and longicorn Trinophyllnui cyibratuni, and the long-leaved pine 

 Nothorrhinn. But the great importance of the families as evidenced in the 

 plains forest has been outclassed here by the Scolytidae. This family in 

 the Western Himalaya contains an assemblage of pests who have at their 

 mercy the whole of the coniferous species, and in every instance, so far 

 as present investigations go, the species affecting a particular tree accom- 

 panies it from the centre to the limits of its habitat. Another point 

 about the distribution of some of these genera, which is known to be 

 the case in other parts of the world, is that one or more appear to be 

 confined to a particular species of tree. There are, e.g., three species 

 of Scolytiis known in the Western Himalaya (S. major, S. minor, and 

 5. deodar a), and they all infest' the deodar. I have never yet taken the 



genus from any other tree in the 

 Himala3'a, nor have I found it at all 

 in the plains. And yet in Europe the 

 genus is confined to broad-leaved trees ! 

 We must look to America for analo- 

 gous instances of its infesting conifers. 

 There is a Polygraphits {P. major), it is 

 true, which will also infest the deodar, 

 Fig. i,.—Polygraphus major, Stelx x i6. but only when it is unable to find a 



sufficiency of its own real host, the 

 blue pine. The important genus Tomicus, on the other hand, does not 

 appear to infest the deodar. One species {T. ribbcntropi) attacks both 

 blue pine (often in company with Polygraphus pint) and spruce (but not 



