proceedings of the third entomological meeting 699 



1. The Beehole Borer of Teak. 



The Beehole borer, Diiomitus ceramicus, Wlk. (Fam. Cossidse) is- 

 the most serious pest we know of teak forests in Burma. It is apparently- 

 absent from India. The caterpillar is a heartwood borer, which attacks 

 teak trees of all ages and sizes from the sapHng 10 inches in girth to the 

 veteran overdue at the "saw mill. The larval gallery or so-called 

 " beehole," which Hes more or less vertically in the heartwood, attains 

 a length of nine inches, and the diameter of one's thumb. The life- 

 cycle is annual and the beeholes formed in one year are overgrown by 

 the next season's wood, so that by the end of its life the teak log may 

 be riddled with beeholes from the core to the skin. Such timber is of 

 course useless for constructional purposes. 



A rough estimate puts the loss at 20 per cent of the gross value of 

 teak in the natural forests of Burma. 



In pure teak plantations in which the borer increases rapidly the 

 loss is likely to be several times greater. No plantations are yet old 

 enough for the final felling, but there is every indication at present that 

 all trees in the final crop will be seriou.sly beeholed. 



The problem of the beehole borer is almost unique. Its work is 

 unusually inconspicuous in the forest and the location of infested trees 

 is in consequence extremely difficult, — even to an entomologist. Not 

 only are absolute numbers very small (there are perhaps not more than 

 one hundred individuals per acre each year), but for more than ten 

 months of the year they are hidden inside the trunk of the tree and no- 

 wood-dust or gum or discoloration is produced to mark the presence of 

 a single borer. The timber merchant is unable to judge if the trees he 

 purchases are badly beeholed, until he cuts them in the saw mill. 



For an insect of such obscure habits it is impossible to conceive 

 control measures based on direct trapping or destruction. Even if a 

 very attractive bait or lure were devised, its practical utilization would 

 be prohibited by the prolonged emergence period of the moth, a period 

 which extends over three months and represents a daily catch of two 

 moths only. And what sort of trap can one devise to kill two Cossid 

 moths per night in a Burma forest, that will not at the same time destroy 

 thousands of other insects of unknown importance ? 



Accepting the premise that we shall not abandon the poHcy of growing 

 teak pure or in plantations, we have now to devise some methods of 

 tending the crop throughout the rotation of, say, seventy years. An 

 obvious remedy is the use of an alternative food-plant as a trap- crop, 

 but at present none is known. In Java the pest is said to attack 

 Sfatliodea camfanulata and Sesbania grandifora, but we have yet to- 

 find an alternative host in Burma. 



