FAMILY SCOLYTIDAE 



575 



Life History. — I first obtained some cocoons of this insect from larval 

 pupatin^-chambers of the scolytid in deodar-trees at Pajidhar in Jaunsar, 

 but failed to breed any flies from them, the cocoons drying up. 



I agrain found the insect in the Simla Catchment Area forests in 

 August igoS. I took from one of the galleries a nearly full-grown 

 Scolytus grub, fixed to the side of which was a small white hymeno- 

 pterous grub pointed at both ends. It was about a third the size of the 

 Scolytus larva and was stuck to it, feeding as an external parasite as shown 

 in fig. 360, a. 



When full-grown the Scolytus grub eats out in the bast and sapwood a 



pupating -chamber 

 in the manner al- 

 ready described 

 and then dies of 

 exhaustion. The 

 parasitic grub then 

 spins a small oval 

 papery cocoon in 

 the pupating- 

 chamber of the 

 Scolytus larva and 

 pupates here. The 

 fly matures in 

 about a fortnight 

 and crawls out of the tree by one of the neighbouring exit-holes of the 

 newly matured Scolytus beetles. 



After pairing, the female Braconid fly searches for a tree into which 

 the Scolytus beetles are tunnelling to oviposit, crawls down one of the 

 entrance-holes, and deposits her eggs in the egg-gallery of the Scolytus near 

 the latter's eggs. On hatching out, each of the parasitic grubs crawls 

 to one of the young Scolytus grubs and fixes itself to it. 



So far as my observations go the parasite appears to pass through as 

 many generations in the year as its host. Whenever I found a tree badly 

 infested with Scolytus tunnelling in it to oviposit I invariably observed 

 some of these flies hovering over the trunk searching for a suitable 

 entrance-hole to crawl into. 



Chalcid. — I have also taken specimens of an unidentified Chalcid fly and 

 grubs from the larval galleries of this scolytid. 



Fig. 361. — Bracon sp., parasitic on Scolytus tnajor, Steb. 

 Flv natural size and enlart^ed. North-West Himalaya. 



Niponius canalicollis, Lewis. ^ — This histerid beetle, which has been 

 already described on p. 507, is one of the chief predators on Scolytus major 

 and S. minor, entering the tunnels of the scolytids to oviposit in them. 



