WOOD BORERS.

Hauraki Plains Gazette, Volume XXXV, Issue 4651, 21 January 1924, Page 1

WOOD BORERS.

DAMAGE TO TIMBER.

ADVICE BY EXPERTS. A bulletin on wood borers Issued frcin the New South Wales Technological Museum will probably be found of great interest to many people, for the damage caused by borers to timber in New South Wales is without doubt, increasing from year to year (states the Sydney Morning Herald). The trouble is of direct importance to the architect, builder, furniture- manufacturer, and hoiisehohler.r Most people are entirely ignorant of,-the' habits of the borer, and it is with a view to disseminating the results of investigation into the insect’s life and outlining precautions to be taken against its destructiveness that the bulletin has been issued. The authors, Mr T. G. Roughr ley (economic zoologist) and Mr MB. Welch, B.Sc. (economic botanist) have discharged their task th broiighly yet simply.

Though few species of forest trees are immune from borers, Messrs, Roughley arid Welch direct attention mainly to the type of borers - which infect seasoned timber and those which confine' their attention to unseasoned wood., Referring to the latter it is recommewded ■ that to minimise risk the bank should be shipped frorii logs as soon as possible after being felled, so that the surface may dry quickly and lose its attraction for the beetle. The life cycle of the beetle has not been accurately established, and pending further research ft is considered imperative that no time should be lost in milling particularly in the case of cabinet timber, and that treatment by creosote should be resorted to. Should the borer gain entry to the green log the only effective treatment is that of steaming in a steam box. A DESTRUCTIVE FOREIGNER. The boi;er, most destructive to seasoned timber is the grub of the “ powder post beetle,” an insect first detected in Brazil, but spread thence by commerce all over the world. It is the grub or larva, living on the tissues of the wood, which does practically the whole of the damage in the interior of the timber ; it is th« beetle, which bores • the so-called flight holes ” seen on the surface. The first external evidence of borer attack- is usually indicated by small heaps of powder coming from pinholes. These holes are made by beetles leaving the timber, and not, as is often conjectured, by the grubs. Whilst the holes seen on the surface may be few in number, the grubs may have been devouring the interior of the wood for 12 months or more, and very considerable damage may have been done during the time, without shbwing any signs of infectation. It is frequently thought that the grub bores the holes, to the Surface and crawls away in search of other timber, into which it penetrates and begins its work of destruction anew. This, however, is entirely erroneous. In the first place it carefully avoids coming to the surface, for when once there it is entirely helpless. Although provided with a pair of eyes and three pairs of legs, these organs are.very primitive, and it can neither .see nor crawl about. - In the second place, it cannot bore its way into timber from the outside. RESPONSIBILITY OF MILLERS. The powder post borer does much damage to h ardwoods, such as scantlings, floorings, and joists, but it confines activities to sapwood, or timber from the outer portion of the log. It also attacks the sapwood of Tasmania.! oak, cedar, Japanese oak, maple; myrtle, silk oak, and other woods. In condemning the milling sapwood the authors of the pamphlet say: “ Tne principal source of the trouble lies in the milling of immature logs. Mills operating in the vicinity of Sydney have in the past supplied timber in which a very great percentage of the wood consisted of sap. In a recent inspection of a number (about 400) of ehlirch seats, 90 per cent, were found to be damaged by the powder post borer. This was founi to be due entirely to the use of spotted gum saplings, which could net have been much more than six inches in diameter. Such narrowsighted business methods are doing incalculable harm to the reputation of our magnificent hardwoods, which are undoubtedly equal to any timbers in the world. The use of edgings for cutting into small dimensioned battens for tiles, etc., cannot be too strangely condemned. It should be made illegal to dispose of sapwood intended for constructional work, unless it is previously given some approved treatment.”

The life history of the furniture grub and beetle resembles that of the powder post beetle in its essentials, with this main difference, that whilst the powder post beetle deposits its eggs in the pores of the the former lays them in cracks and crevices. There is a difference in habit, too, for the “ powder post beetle ” shows a partiality f or newly seasoned timber, but the furniture beetle has a decided preference for wood which is old and thoroughly dry. The use of creosote, orthodich lot-benzine, turpentine, corrosive sublimate, and arfeenate of soda is recommended as deterrents and eradicators. But the most positive of all-remedies is heat.