198 



INTRODUCTION. 



The larvae of the ScolttidjE very closely resemble those of trie- 

 ordinary Ehykciiophora ; the head, perhaps, is a little longer 

 and stronger, and the mandibles, as might be expected, somewhat 

 longer and more developed : the larva of Platypus is somewhat- 

 different from the ordinary Seolytid larvae, being more elongate 

 and cylindrical and terminating in a short spine. 



About 1500 species are known as belonging to the family. 

 Most of the principal genera are represented in India and Ceylon, 

 and, in view of the ravages they commit on forest-trees, a know- 

 ledge of the habits of these insects and of the means of reducing or 

 exterminating them is of the utmost importance for all who are 

 connected with the Department of Woods and Forests in India 

 and Burma. 



It may, perhaps, be of advantage in this connection to quote 

 the general description of the life-history of the Scolytldvi;, which 

 was kindly communicated to me by Mr. W. F. Blandford for my 

 work on the British Coleoptera (v, p. 401) : — 



" In the fact that the female enters the trunk or plant to lay 

 her eggs the Scolytid.e differ from aJl other Bhynckophora by 

 which the eggs are deposited from the outside. 



" The process of establishing a brood begins in every case by 

 the formation of a vertical entrance-hole through the bark, which, 

 in the wood-boring forms, is continued deeply into the tree, but 

 which, in the bark-feeding species, only reaches at most the 

 surface of the wood. 



" To begin with the latter: — The entrance-hole is usually gnawed 

 by the mother; but some species are polygamous, and in these the 

 male performs the operation. He then hollows out a small 

 irregular cavity — the brood-chamber; there certain females betake 

 themselves, and, after impregnation, commence the ' mother-gal- 

 leries ' at the junction of wood and bast. In the monogamous 

 species the female is fertilized in the entrance -passage or just 

 outside it. From the termination of the entrance-hole the 4 mother 

 galleries' run- — sometimes two in number; in the polygamous 

 species they form a star-shaped system radiating from the brood- 

 chamber. The eggs are laid alternately on the right and left of 

 the galleries in small excavations from which the larval galleries 

 start. Occasionally they are laid in a clump, and the larvae feed 

 in an irregularh' advancing column without forming distinct 

 galleries. The dead body of the mother is usually to be found 

 at the end of her gallery, and it may thus often serve as a clue to 

 a species which is met with in the larval state. 



" The larval galleries usually commence at right angles to the 

 4 mother-galleries ' — at least at their middle ; but they often change 

 their direction irregularly, the different shapes of the borings 

 being characteristic of the species. Their length is variable, and 

 depends on the extent to which they are channelled in the wood. 

 In some species the galleries, which score the wood deeply, are 

 only about one inch in length, while in others they are often four 

 or five inches long and sometimes very irregular; they end in an 



