THE WOOD-BORER AND ITS CONTROL.

New Zealand Journal of Agriculture, Volume XVIII, Issue 4, 21 April 1919, Page 198

THE WOOD-BORER AND ITS CONTROL.

By

A. H. COCKAYNE,

Biologist

Various timbers are often destroyed through the larval activity of certain beetles popularly known under the general name of the “ woodborer.” Timber affected with these insects is often said to be affected with dry-rot, a term that really should be used only when the damage is caused by one of the timber-rotting basidiomycetes. It is generally considered that an introduced . beetle, cosmopolitan in its distribution and known scientifically as Anobium domesticum, is the one mainly responsible. There are, however, many New Zealand species of Anobium, and several of these undoubtedly cause considerable damage.

The extremely bad reputation that the Anobium wood-borer has gained as a timber-destroyer is due to the fact that it is extremely

partial in its attacks to the New Zealand white-pine (kahikatea) and kauri. As both these timbers were commonly used in houseconstruction in the earlier days of settlement the wood-borer soon became a serious consideration. So bad are its ravages on whitepine, especially any that may contain sapwood, that this timber fell into complete disuse for internal house-construction. For many years white-pine was almost unsale-

able, and it was not until the advent of export dairying that this timber again became valuable.

Anobium domesticum is likely to bore into a very .large variety of timbers, especially any that may contain appreciable amounts of sugar in their wood-cells. In general, however, it is only in white-pine and kauri that the most extensive damage is done. In both these timbers good heart-wood is likely to be affected, but with other timbers, such as red-pine (rimu), only the sap at times is likely to become riddled by the larvae of the beetle. When timbers are stored for many years without much free ventilation species not normally affected may be attacked. This has well been shown in museum material from time to time.

The life-history of Anobium domesticum has not been worked out in detail in New Zealand, but it here seems to follow much the same lines as in Europe and America. The larvae, after tunnelling and feeding in the timber from one to three years, emerge during the months of November and December. During this period a good many may be swept up each day from the floors of affected houses. The beetles each day lay from eighty to one hundred and fifty eggs. This will be done in crevices in the wood, or short bores will be made and several eggs deposited in each hole. In affected timbers the eggs are frequently laid inside old tunnels, and this often makes it impossible to spray for

killing the young larvae before they enter the wood. Anobium domesiicum is not really single-brooded, but as beetles usually emerge each early summer it is generally looked upon as such.

CONTROL MEASURES.

The control of wood-borer falls under two headings —(i) in house or building timber, and (2) in movable furniture. So far as woodborer treatment in building-timber is concerned, this is yearly becoming of less importance. The majority, of the old : badly infested houses have been replaced by buildings , in which white-pine is no longer used. It is only occasionally that renovation of badly infested buildings can be satisfactorily undertaken. The replacement of floorings and linings with red-pine or black-pine (matai) can, however, be done at times. When infested material is . removed it is best done in late autumn to early spring, and the timber removed should be destroyed as soon as possible. The joists, &c., should be sprayed with a solution of arsenate of lead, using it at the rate of 1 lb. to 28 gallons of water.

In houses where only one or two boards are affected I always recommend the removal of the affected timber rather than to attempt any direct control. If, however, the cost of doing so is prohibitive, the affected wood should be sprayed in November, December, and January three times with a mixture of benzine and creosote, using five parts of benzine to one of creosote, or a -mixture of benzine and naphthalene, dissolving about the equivalent of two moth-balls of naphthalene to every | pint of benzinfe. Benzines of the type of “ Powerin ” will be found very effective, as they evaporate a little slower than do the lighter types. Spraying with arsenical compounds is . often recommended, but the habit of the beetle laying its eggs in old tunnels often makes this method unsatisfactory. The adult beetles appear to feed very little, and any poisonous spray must kill the larvae emerging from the eggs rather than the mature insect.

So far as furniture is concerned a word of warning against the purchase of second-hand furniture'is necessary. In many cases such furniture will be the means of introducing borer. Care should always be taken to see that any such furniture is sound before introduced into a house. Borer in chairs, tables, pianos, and other articles of furniture should be systematically treated. Benzine and creosote squirted into each hole with a small pipette, and then the entrance stopped with a pellet of soap, will be found the best treatment to adopt. Where the wood is extremely badly affected it will be best to get rid of the article rather than try to control the borer. A very good method of dealing with the pest is to keep a sharp lookout for the appearance of any dust or frass being ejected from the holes. Whenever this occurs the larvae are very easily reached with an application of benzine, and treatment directly such dust appears is often entirely satisfactory, even when only once applied.

As a rule the early calf thrives the best. It is good practice to wean before the normal summer dry weather sets in, for then there is sufficient succulent herbage for the calves, and they do not receive a. check.