i6o FAMILY BOSTRYCHIDAE 



Mandla takes some two to two and a half months, from February to near 

 the end of April, for the tree in question was a green healthy one before 

 being felled in February, and showed no signs of previous insect attacks. In 

 this tree I was able to see a good example of the way the beetle curves its 

 egg-tunnel concentrically round the rings of the wood. I show a diagram 

 of this in fig. 104 from a dra\ving made on the spot. 



These three sets of observations prove that S. crassuui has at least 

 three broods in the year in the Central Provinces, the first between 

 February and April, the second from April to July, the third from July 

 to September. It is possible that the beetles of a fourth may issue early in 

 November and tunnel into the shoots and twigs of trees to hibernate, or the 

 September generation may act in this manner. 



Towards the end of May 1906 I took the beetle in Dalbcrgia sissoo on 

 the Sunkos River in Assam. There is a considerable amount of more or less 

 scattered sissu growth along the banks of this part of the Sunkos. I 

 examined this to ascertain whether the leaf-rolling Apoderus weevils (p. 416) 

 were at work here. I did not find them, but I found a blown-down tree full 

 of the bostrychids S. crassum and S. anale. In this attack I noted particu- 

 larty the way the beetles sometimes carry a portion of their egg-tunnels, curving 

 round the circumference of the tree, leaving merely the thinnest of lamellae 

 of outer sapwood (in places where the bark had fallen off) as a protection to 

 the gallery, rather after the fashion in which termites work. This generation of 

 beetles taken on 26 May 1906 was just maturing, and the bulk of the beetles 

 would evidently issue early in June probably those of the second generation 

 of the year, who would lay the eggs of a third generation in June. 



I was down in Tenasserim in March 1905, and in the latter part of the 

 month I went for a trip up the Ataran River by launch. \Ye burnt fuel on 

 the launch, and an examination of this material showed it to be badly 

 infested by bostrychid beetles. One small log of Albizzia procera was almost 

 entirely riddled by S. crassum beetles, and scarcely scaled one-sixth of its 

 proper weight owing to the amount of wood which had been eaten out by 

 the beetles and their grubs. The whole of the interior was a network of 

 tunnels. The generation was just maturing, many of the beetles having 

 already left the tree. Numbers of others were engaged in eating out their 

 flight-holes. My attention was drawn to this, as the outer surface of the 

 log contained a number of holes much too small for S. crassum to leave 

 by. I thought another smaller bostrychid was present, but an exami- 

 nation showed these holes to be the partially eaten exit-holes of the 

 beetle. This was interesting, as it proved that the third \veek in March is 

 the time of appearance of what is probably the first generation of the 

 beetles issuing to lay the eggs of the second, and secondly that the 

 greater part of a flight of this species mature and leave the tree together, 

 and that there is consequently not so great an overlapping of genera- 

 tions as obtains amongst the Scolytidae. This I have noticed on other 

 occasions. 



