TERMITE PEST

Dominion, Volume 34, Issue 42, 13 November 1940, Page 9

TERMITE PEST

Establishment In New Zealand DAMAGE TO BUILDINGS Report By Australian Entomologist When it was discovered last year that Australian termites (white ants) had become established in Auckland and New Plymouth, and that they were causing serious damage to buildings and attacking power-poles, the New Zealand Government requested the Australian Commonwealth Council for Scientific and Industrial Research to make an officer available to report on the situation and recommend measures for dealing with the problem that had arisen. In accordance with this request Mr. T. N. Ratcliffe, senior entomologist, visited the Dominion some time ago and spent five weeks in the country. In his report to the New Zealand Government, a summary of which was made available yesterday, Mr, Ratcliffe states that the only way in which the spread of white ants in New Zealand could be checked, and the established infestation brought under control, would be. by an organized campaign of locating and poisoning colonies. "Termite infestation is not new to New Zealand,” says Mr. Ratcliffe. “A native species, calotermes brouni (commonly called the dry-wood termite), attacks timber in buildings, particularly in the North Island, and sometimes does considerable damage. C. brouni is what is known as a wooddwelling termite, the colonies being confined to the timber on which they feed, and requiring no soil connexion. Certain relatively innocuous wooddwelling species have been introduced into New Zealand from Australia: the termites whoch had given rise to anxiety, however, were species of the notoriously destructive soil-dwelling t subterranean) genus coptotermes. Species of this genus form colonies which may contain up to and over a million individuals, and which can operate a considerable distance from their nests. "The nest takes the form of a .more or less spherical mass of concentrically arranged chambers with thin and brittle papier-mache-like walls, and is usually located in the heart of a stump, tree, post, or pole, near ground level. The termites reach the wood on which they feed by subterranean galleries; and if the wood is out of contact with the ground, they will build earthen covered runways over inedible materials (brick foundation walls, for instance) to reach it. Timber Eaten Away. "The introduced coptotermes are easily distinguished from the native dry-wood termite. They are smaller and much more active. They usually occur in large numbers and the damage done to timber is characteristic, the wood almost always being eaten away to a series of thin parallel sheets. Another characteristic is their habit of Alling cavities and cracks in in timber with clay. "The destructive powers of the different species of coptotermes vary. The operations of a populous"colony of one of the more voracious species can, in five or six years, reduce a timber building to a dangerous condition, necessitating extensive reconstruction. On the oilier hand, a house may be infested for a decade without serious dam- ■ age being done. -Three species of coptotermes have become established in New Zealand. One of them, C. acinaeiformis, is the , most destructive species of the genus, being Australia’s principal pest termite. The other two can be regarded as of secondary importance. They have not yet demonstrated their ability to spread under New Zealand conditions. It may be mentioned that 0. acinaeiformis (which can and is spreading in New Zealand) does not occur in the cool temperate regions of Australia. There is reason to believe that it would not flourish in many parts of the South Island or in the more elevated parts of the North Island. Indeed, the whole of the South Island may escape infestation. Auckland Infestation. "From the observations made and the information received during my visit, ■the following picture of the extent and nature of the established coptotermes population in New Zealand was obtained. In Onehunga there is an ‘infestation area,’ extending from Grey Street in the south, along Queen Street, Trafalgar Street, Auckland Road and Manuktiu Road to the level of Beckenham Road or Gladwin Road. "Outside this main area of infestation coptotermes has been discovered in apparently isolated spots in the following districtsßemuera,’ Herne Bay, Grey Lynn, Mount Albert and Devonport; and there is also a ‘spot infestation’ in south Onehunga. In New Plymouth there is a small infestation area, also of unknown width, extending for about 300 yards along Breakwater Road; and one ‘spot, infestation’ was discovered in Morley Street, opposite Western Park. Information was also received suggesting that coptotermes'might be established in Dannevirko and Wanganui; but I was not able to confirm this. Unfortunately there is reason to believe that C. acinaeiformis is responsible for practically all the New Zealand infestation. Attack on Poles. "In the main Onehunga infestation area the termites have already demonstrated the great adaptability they display in Australia. They have attacked, and are attacking, fence posts, poles, ete.; growing trees (a puriri and a pohutakawa were observed to be infested, as was a tree of th<- latter species in New Plymouth) ; and the timber in buildings, even in brick residences. "'The number of poles infested by coptotermes is a striking feature of the situation; and it has naturaliy attracted notice. Since the poles are of Australian hardwood, and the termites of Australian origin, there might bo a tendency to jump TO the conclusion that, these poles are rhe cause of the spreading infestation. This is not so, however. The poles tire being infested in situ, just as are, the fences, the buildings, and the trees. '1 hoy are frequently infested because, as ereet- ■ ed in New Zealand, they provide the conditions known to be essential for the successful foundation of new colonics by the winged reproductive forms after the socalled swarming flight, these conditions being decaying wood in contact with the ground. "The present extent of the infestation in New Zealand and the total number of buildings affected are relatively unimportant matters in comparison with the following facts which are revealed by an examination of the infested areas in Auckland and New Plymouth:—(lt Coptotermes Acinaeiformis is finding conditions very much to its liking, for it is obviously spreading actively; colonizing flights of winged reproduetives regularly occur, and

the successful foundation of new colonies has repeatedly taken place; (2.1 the lowbuilt New Zealand timber houses may be said to invite infestation; the wood of which they are constructed is susceptible (none of the main timbers used in building construction —rimu, totara, matai, kauri, heart or sail —appear to possess any resistance to coptotermes) ; and they are built in such a way that the termites have no difficulty whatsoever in gaining access to them; (3) the damage liable to be done before an infestation becomes obvious may involve costly repairs ; thus one or two houses are known to have been substantially' recoustructed, and oue has been completely rebuilt, as a result of coptotermes damage. Destructive Potentialities.

"The implication of these facts should be immediately obvious,” Mr. Ratcliffe continues. "Given the opportunity, which ■ they will take unless prevented, the introduced subterranean termites can and will do an immense amount of damage. It would he foolish to attempt to estimate their destructive potentialities under New Zealand conditions, but in this connexion it may be mentioned that in Adelaide, a city of stone aud brick buildings, where, moreover, it is standard practice to use jarrali (a resistant timber) for bearers, joists, and plates, it is estimated that the damage done annually by termites is to the value of at least £40,000 —and coptotermes acinaeiformis is the species primarily concerned. It should be perfectly clear to every thoughtful person that with the introduction, establishment, and spread of this termite in Netv Zealand, the Dominion is now confronted with a very' grave problem indeed, and one which, if not faced and tackled without delay will be increasingly difficult to handle successfully. “The only’ way in which the spread of coptotermes in New Zealand could be checked, and the established infestation brought under control, would be by an organized campaign of locating and poisoning, colonics whensoever they' were operating. Thoroughness and vigour would have to be the keynotes of such a catnpaigu, which could clearly only be carried out under Government aegis. Unless inspectors could enter any place or premises where infestation might exist, and unless every infestation discovered were treated, it would hardly be worth while undertaking the campaign at all. “A flourishing mature colony ot coptotermes will liberate, each year, some 50,000 winged reproduetives, any pair of which, if it is successful in finding suitable conditions, can found a new colony. Thus if a householder refused, perhaps under the impression that he was thereby protecting his own interest, to permit his premises to be inspected and treated, he would in effect be protecting a focus of danger. The continued existence of even a few large colonics would nullify all the effort put iutq an otherwise successful control campaign. For this reason I do not thing that a campaign of control could be carried out with the necessary degree .thoroughness unless those conducting it were given special powers, such as could only be couferred on them by legislative action. ‘•The extermination of a colony oi soil-dwelling termites (the nest and reproductive centres of which is often virtually impossible to locate, and may be some distance from the scene of the insects’ operations) is not a simple matter. The mere killing, say, by fumigation, of the insects present in the timber ot a building will not result in the extermination of the colony, neither will it in any way render the building immune from further attack. The only method of treatment likely to be effective consists of the use of poison dusts, which are disseminated through a termite colony •by the social habits of the insects themselves. I have discussed with the Aew Zealand authorities the question of poison dust treatment, and have provided them with all the information available on the matter.

"I found it difficult to offer advice regarding tlie extent, to which terinite-proot building construction should be adopted in New Zealand, as Illis must depend on the results obtained by the campaign of control. It might be as well to point out, however, Hint termite-proof construction cannot be dispensed witli allogether, for the complete eradication of coptotermes in New Zealand cannot be hoped for; at best its spread can be checked and the established infestations brought under control. “The general public learned of tlie presence of eopto termes in Auckland a little over a year ago, when news ot its occurrence got into tlie Press. Learning no.w that it has established itself, and very solidly, in an area over a mile across, and’ has got. a foothold in lialt n dozen districts as far apart as south Onehunga and Devonport. people will naturally assume that the pest is a rapid spreader. Fortunately, this is not so. despite tlie fact that tlie i-<doiiy-foiinding reproduetives can be carried several miles by the wind. "From tlie size of some of lhe colonies discovered in Auckland and our knowledge of the rate of growth of colonies of these soil-dwefling termites, it is possible to state categorically that coptotermes must have been introduced _ into Auckland at least 25 years ago. This, on the whole, is encouraging. It. means that the trouble is likely to develop comparatively slowly; and if tlie problem is tackled vigorously, tliere is more than a reasonable chance that the pest can be bottled up. and the termites kept out pf all hut a few e-m.'ill areas during the lifetime of most of the existing tiiule-i- buildings. Another encouraging tiling is that from our knowledge of the habits ol these termites in Australia it is fairly certain that, they do not constitute a menace to the commercial forests of the Dominion.