478 FAMILY SCOLYTIDAE 



The mother beetle, as is the case with the Scolytus of the deodar, remains 

 alive for a considerable time after finishing ovipositing, the entrance-tunnel 

 in the bark and the egg-gallery being kept free of all wood particles and 

 dust : the larval galleries are, however, closely packed with these materials 

 and larval excreta. The female finally dies in the entrance-tunnel, and 

 thus blocks it. The predaceous histerid beetle Niponitis andrewesi appears 

 to be aware of this habit of the Sphaerotrypes, and usually crawls down the 

 entrance-tunnel, thus reaching the lower part of the egg-gallery, where she 

 oviposits whilst the bark beetle is still engaged in eating out the upper 

 portion of her gallery and completing her egg-laying operations. 



The eggs laid by the March beetles are those of the first generation of 

 the year. The larvae hatch out within three to four days of the eggs being 

 laid, perhaps in even a shorter period, and become full-fed at about the end 

 of April. The pupal stage lasts from ten days to a fortnight, and the first 

 generation of beetles issues some time in May. The May beetles lay eggs 

 which give rise to the second generation of beetles about the end of June to 

 the middle of July ; these lay eggs which produce a third generation of beetles 

 at the beginning of September; a fourth generation of beetles, from eggs 

 laid about the first week in September, emerges in the first week in October ; 

 the eggs from these give rise to the beetles which are found in the bark 

 of standing trees in the winter season ; they issue about the middle of 

 November. It is probable that the whole of this, the last generation of the 

 year, rarely matures before the first cold of the winter sets in. The immature 

 pupae and full-grown larvae have then to hibernate in this condition in the 

 larval galleries. To do this the larva spins around itself a fine silken cocoon, 

 and thus usually manages to pass safely through the winter. Most of the 

 pupae are probably killed off by the cold. 



In May 1902 I discovered the beetle tunnelling into a small green shoot 

 of a living sal-sapling in the Dehra Dun forests. The beetle was alive 

 and only the extremity was visible, the rest of the insect being buried in 

 the green shoot. In subsequent years I was able to corroborate this 

 observation and to ascertain definitely that the beetle tunnels into and 

 feeds in young green sal-twigs. 



During the cold season of 1908, Mr. Reich, a third-year student at 

 the Imperial Forest College, Dehra Dun, discovered a dying Anogeissus 

 latifolia tree in the Garhwal Division showing the characteristic galleries 

 of this insect. Unfortunately no beetles were procurable. The writer 

 had previously taken the insects tunnelling into newly felled Anogeissus 

 latifolia posts in April 1905, at Horai, in the Kumaun Division, United 

 Provinces. 



In September of 1908 and of 1909 I had some green sal and Tenni- 

 nalia tomentosa trees felled at Lachiwala, in the Dun, and investigation 

 showed that the Sphaerotrypes also infests the Tenninalia in a manner 

 similar to that of S. globulus (cf. pi. xlii), although not apparently so readily 

 as the sal when the two trees are present together in the locality. 



