TIMBER PESTS.

Press, Volume LXIII, Issue 19154, 10 November 1927, Page 4

TIMBER PESTS.

DESTROYING THE BORER. CLEANING-IT TIME. At the invitation of Mr X. K. McKcnan. of the New Hydro-Vacuum Co., Ltd., 31' Collins street, Melbourne, a number of men interested in the timber business visited Mr Martin Hannah's timber exhibit at the Melbourne Show to see a display of timber seasoned by u new process, and old timber treated for the eradication of the borer, white ant, and similar pests. The processes by which the timbers are treated in each case are based on a system of operations within a vacuum, and it is claimed that they will revolutionise the timber industry.

In regard to the seasoning process, it, is claimed that by the new method freshly-cut green timber can be thoroughly seasoned in nine days, though in the ordinary way the seasoning process takes one to two years. It was explained that under the new process the green timber was stacked on trucks and run into a concrete kiln, which then was hermetically sealed. A vacuum was drawn, and when the atmosphere pressure was so released the cells of the timber exuded moisture towards the vacuum. The exudation took place evenly from the inside to the outside of the timber, and the moisture as it reached the surface was evaporated by heat supplied by a system of pipes heated by steam or electricity.

Samples of various Australian timbers seasoned in nine days by the new process were on view at the exhibit. They were straight, dry, ami strong, showing, to all appearances, that their quality and strength had not been impaired in the slightest degree by the rapid method of seasoning. Some of the samples were sai' 1 to have been seasoned (by the new method) eighteen months ago, and they showed no sign of warping or cracking.

Rapid Heating Process. There were on view also a sideboard of ash and a secretaire of Queensland maple,'the timbers of which were said to have been sea. ncd by a rapid heating process, but without the vacuum, sixteen years ago. They, too, were in perfect condition. Samples of timber preserved by the application of creosote oil under the vacuum process were exhibited. The use of creosote oil, it was explained, had a world wide recognition as the best means of preserving timber, but the mere external application of the oil to wood was not effective in killing borer, white ant, or fungus. The vacuum process enabled timber to be impregnated with creosote oil in a few hours, and the complete penetration prolonged the life of the wood, and gave immunity against attack by insect pest or fungus. One sample was a small piece of timber in the midst of a white-ant nest. It was in perfect condition, though it was claimed that the wood had been in the n£st for three months, under the supervision of the Government Entomologist, Mr C. French, jun. Samples of timber in which borer and white ants had been by the new process were of particular interest. It was explained that the infected timbers were placed in the seasoning kiln, and when the vacuum was created m poisonous gas was introduced. In a few hours all forms of life—whether they be egg, larval, or beetle forms—in the timber were destroyed completely, without injury to the timber or polish. The Beetle Stage. It is once more the time of year when sawmillers and timber merchants (and builders with timbcryards) should take special trouble to clean up their logskids, mills, yards, and timber-racks; for it is at this time that the boring insects start to emerge in beetle stage for the purpose of propagating their species. All log or wood refuse, dockings, and wood litter should be thoroughly raked up and burnt, and all old buildings, empty timber skids, racks, etc., should receive a liberal spraying with creosote. Even the yard roads and spaces between and underneath the racks and stacks should be sprayed also. Such precautions would very largely prevent the spread of borers to existing stacks and* stocks of timber, and would assist materially in reducing the borer menace. As illustrating the necessity for these precautions, we, recently had sent to us from Greymouth a sample of otherwise sound, clean 0.8. rimu, from a stack in the railway workshops yard there, which was thoroughly riddled with borings of a fairly large grub. A specimen of the beetle found in the borings was also forwarded for identification purposes. The specimens were submitted to the Government Entomologist, who at once identified the beetle as the "two-toothed longhorn," otherwise ambeodontus tristis (or the "lesser hu-hu"). This beetle is a native of New Zealand, and one time confined its attentions to dead or injured trees in the bush, or tho dead timber left on bush clearings. Of recent years, however, this destructive insect has enlarged its sphere- of activities, and is now very prevalent in houses, particularly in "Wellington. Insectivorous Native Birds. The reason for the spread of this insect is undoubtedly the upsetting of tho balance of nature by the disappearance of a number of our insectivorous native birds and the reduction in numbers of others. Moreover, of recent years, more and more farm lands have been cleared, and on the older felled country the logs and stumps are now quickly disappearing. Hence the boring insects are forced further afield and to new environments in search of timber on which to live—for they "bore to live," not necessarily "live to bore."

Recently, also, there was sent forward to us for identification of the insect, a section of a rimu log, from Taumarunui district, that had been very heavily attacked by a borer on the mill log-skids. The log had been felled only about six weeks when the depredations of the borer were detected, and it was found that the sap was very freely infected under the bark. Tho insect responsible has been identified by the Government Entomologist as a native weevil known as the "platypus," and it has always been fairly prevalent in most bush districts. It particularly attacks unhealthy or dying trees, and is the first to get busy on dead or dying timber after a bush burn. It it "also responsible for the "pinhole" bores found so often in the heart of beech (or birch), particularly in tho butt. In the case of the sample of log referred to, it is probable that the tree was attacked before being felled, and that the tree was unhealthy and pos-

sibly in process of dying from old age or suppression by taller and more vigorous growth surrounding it.—"lndustrial Bulletin."