A NOTE ON THE PRESERVATION OF BAMBOOS. 221 



invariably if not invariably), responsible for the riddling of bamboo in Calcutta 

 (and possibly to the south throughout the Madras Presidency) is D. mhiulus, 

 whilst its confrere D. pilifrons would appear to confine itself to Upper India. % 



A series of experiments and observations were conducted at the Indian 

 Museum throughout the greater part of the year 19f 3 (as fully detailed in the 

 note in the Appendix Series) with a view to ascertaining whether it was possi- 

 ble by impregnating or soaking the bamboo with some preservative material to 

 protect it from the shot-borer's attacks, It may be mentioned that incidentally, 

 in the course of these experiments, a large amount of information was obtained 

 on the life-history of D. minutus and of the reasons which lead to its being 

 such a pest within the area of its depredations. 



The bamboos experimented with were some from a lot received at the 

 Government Telegraph Workshops in Calcutta from Northern India. They 

 had been cut in the cold weather of 1902-03. As already explained in the 

 previous note, these bamboos were to be converted into field telegraph posts, 

 and in the hope of giving them some protection against the shot-borer pest, they 

 were subjected to a series of soakings in water, copper sulphate and Rangoon 

 oil. For over eight months untreated bamboos and those treated with one or 

 more of the above solutions were kept under close observation, all the lengths 

 experimented with having been received direct from the Workshops, chosen at 

 haphazard by the Superintendent. As a result of the cavefully recorded 

 observations throughout this period, it was proved that the untreated bamboos 

 were invariably attacked by the shot-borer, D. minutus, within a couple of 

 months, i.e., between March and May ; that soakings in water alone or water 

 followed by immersion in the copper sulphate solution were equally innoxious 

 to the beetles ; but that those bamboos which had proceeded the stage further 

 and had been soaked in the Rangoon oil were immune from subsequent attack 

 by the pest. It was shown that the insect passes through no less than five 

 generations in the year, different swarms of adult individuals appearing in 

 April, June, July, September and October, and that the attacks of one or more 

 of these generations with those of their resultant grubs would ordinarily have 

 reduced the bamboos, if untreated, to powder ; it was therefore held to have 

 been proved as a result of the experiments that the life of the bamboo had 

 been lengthened by at least a year as a direct result of the impregnation. 



It has since been possible to trace the history of these treated bamboos, all 

 of which were converted into field telegraph posts, a stage further in their 

 career, and the evidence that has been obtained both by the use of the posts in 

 the field and, equally important, by their storage in an open shed without any 

 special protection being afforded to them in the Workshop yard, points 

 to the wonderful efficacy of the oil treatment. It is the purpose of this 

 supplementary note to give publicity to this fact, firstly, owing to numerous 

 enquiries as to the necessary treatment to be given to the tambocs havirg 

 been received from the Public Works Department, and, secondly, tecauee the 



J nv/e Depart. Not. Ins. wh. aff. For J\o. 2, 1G8. 



