FAMILY SCOLYTIDAE 4^3 



even bent sharply to one side, but this hitter is not usnaL It was especially 

 visible in the case where the insects w^ere egj^-layinj,^ in ver\' green trees (fig. e). 

 The number of eggs laid is thirty-five to forty on each side of the gallery, or 

 seventy to eighty in all per beetle, and the larval galleries are two inches in 

 length. The male beetle remains alive whilst the female is eating out the 

 egg-gallery and ovipositing, and is usually to be found blocking the entrance- 

 tunnel near the pupating-chamber. Since the beetle is preyed upon by 

 Xipouius andrewesi (p. 480), which enters the tunnels of the bark-borer, the 

 continued presence of the male would seem to be for the purpose of 

 protecting the female ; or it may be, as already mentioned under siwalikensis, 

 that the female pairs with the male several times during the process of 

 constructing her gallery. 



At the end of April the insect is to be found in the full-grown larval, 

 pupal, and immature and mature beetle stages in the trees, this being 

 evidentl}- the first generation of the year. A proportion of the beetles will 

 have already issued and will be found egg-laying in other trees. A com- 

 parison will thus show that this insect in Assam is nearly a generation ahead 

 of its confrere S. smmlikensis of the Northern India sal areas. The fact 

 that a generation of beetles has left the tree can easily be ascertained, 

 as, owing to the ends of the larval galleries, i.e. the pupal chambers, 

 being all situated on the circumference of a rough ellipse, and to the 

 fact that the mature beetles bore straight out of the bark from the pupal 

 chamber in the bast layer and sapwood, a regular series of exit-holes form- 

 ing an ellipse is to be seen on the outer bark. When they have matured 

 the beetles leave the trees in swarms together at night, and search for 

 suitable trees in w^hich to oviposit. By the middle of May the beetles of the 

 first generation of the year were busily egg-laying in the Kachugaon forests, 

 and some larvae had already hatched out and commenced to eat out their 

 galleries. x\t the end of the month some of these latter were already 

 tw^o-thirds grown both in the Kachugaon forests and in the Rajabhatkhowa 

 sal areas. This is as far as the life history has been carried. I am of 

 opinion that it will be found that the insect has at least five generations in 

 the year, the beetles of the second appearing the first or second week of 

 June; those of a third at the end of July; a fourth in the middle 

 of September; and a fifth towards the end of October. It is the grubs 

 and the beetles of this last generation which hibernate and egg-lay in the 

 following March. As soon as the first snap of cold makes itself felt, the 

 grubs will leave off feeding and remain in a comatose condition in their 

 galleries. The beetles which have already issued probably do as their 

 Northern India ally does, bore into the thick bark of sal-trees and hiber- 

 nate in this. It is not impossible that in the hot damp climate of Assam, 

 in favourable seasons, the October beetles may pair and oviposit at once, 

 and that a sixth generation may be passed through before the advent of a 

 cooler temperature puts a stop to their work. The beetle tunnels into and 

 feeds in green shoots of the sal in its mature state. 



H H 2 



