Drywood termites in Queensland
B.C. Peters and J.F. Kennedy
Australia has more than 300 species of termites in three broad categories - subterranean termites, dampwood termites and drywood termites. Subterranean termites are generally ground-dwelling or require contact with the soil or some constant source of moisture. Dampwood termites generally live in damp rotting logs or rot pockets in dead or living trees. Drywood termites obtain water from the wood in which they feed and have no contact with the soil, nor any other source of moisture.
This publication deals only with the drywood termites of economic importance in Queensland. Biology, pest status and control measures are discussed.
Biology of drywood termites
Three genera (groups) of the family Kalotermitidae are included here with drywood termites: Incisitermes, Bifiditermes and Cryptotermes.
Incisitermes barrett Gay and I. repandus (Hill) occur in coastal areas of north Queensland. They cause little economic damage. Bifiditermes improbus (Hagen) can cause damage in power poles. Eleven species of Cryptotermes are known to occur in Queensland. Most of these are confined to the coastal and adjacent tableland areas, but some have been recorded further inland. Generally each species has a relatively restricted distribution within these areas.
Figure 1. Three forms of the West Indian drywood termite
Reproductive Soldier Nymph
Of the five species which attack timber-in-service, only one is native to Queensland. Three of the four exotic drywood termites are confined to a small area in north Queensland, and the fourth to specific areas in south-east Queensland.
The native drywood termite Cryptotermes primus (Hill) is widely distributed throughout coastal and adjacent tableland areas and is common in most pre-1940 domestic areas in Queensland. It can attack dead wood of living trees and timber-in-service. Colonies have up to 200 individuals, generally with less than 10 soldiers. Soldiers are pale cream in colour, 4-6 mm in length with short thick dark heads. Alates are pale yellow-brown with iridescent wings. Frequently, damage is caused to timber-in-service including house stumps, flooring, skirting boards, beams, furniture and fence posts. The native drywood termite is very common in the sapwood of house stumps which may act as a source of infestation in flooring. Sometimes it enters flooring through emergence holes of the Queensland pine beetle. In natural situations, it is often found in association with other termite species.
The West Indian drywood termite Cryptotermes brevis (Walker) (Figure 1) is considered the world's most destructive drywood termite and has caused considerable economic damage to timber-in-service wherever it has become established. The only places in Australia where this has occurred to date are Brisbane, Maryborough and Rockhampton in Queensland. It also has been recorded in Sydney and Canberra. An eradication campaign was implemented in Maryborough in 1968 and extended to Bundaberg in 1974. The West Indian drywood termite was proclaimed a notifiable disease under the Diseases in Timber Act 1975. In 1976, it was discovered in several multi-storey buildings in Brisbane and a major fumigation program was undertaken in 1979. About 570 buildings, including suburban houses, and many furniture pieces have been treated in Queensland since then. West Indian drywood termite attack is restricted to construction timber, furniture and, rarely, paper products. There is no record of its occurrence in other situations. It is most commonly found in pine, especially hoop pine, and cabinet woods such as maples Flindersia spp., red cedar Toona australis and silky oak Grevillea robusta. The faecal pellets ('frass', Figure 2) of this termite from hoop pine are characteristically reddish-brown, gradually blacken with age and are usually different in shape from that of the native drywood termite. Typically C. brevis frass is larger and more pointed and the head of the soldier more wrinkled than that of C. primus .
Fig 2. Drywood termite frass
Cryptotermes cynocephalus Light and C. domesticus (Haviland) have been introduced to areas around Cairns, and further northward, from South-East Asia and the Pacific region, principally through commerce. Similarly, Cryptotermes dudleyi Banks has been introduced to Thursday Island and is established. In these areas C. domesticus, in particular, causes substantial damage to houses (flooring, internal partitioning, battens, plywood sheeting and doors), furniture, posts and stumps. Attack has been recorded in a wide range of timber species. Only on Yam Island and at Mossman has C. domesticus been recorded in dead stumps and native shrubs in natural bushland.
Building inspection
Regular inspections will not prevent attack, however, they will minimise the amount of damage caused before infestations can be eliminated.
Where to look
Drywood termites may be found in any wooden part of a building from ground to roof, in furniture, ornaments or paper articles. They have been found in a wide range of timber types. Most rainforest timbers, pines and less dense hardwoods can be attacked. The sapwood of most timbers used in buildings and furniture is also susceptible.
What to look for
Look for small piles of frass (Figure 3). The frass consists of pellets which are hard and smooth with a sandy feel, quite small (about five pellets on a pinhead), and similar in shape, size and colour (light to dark brown, sometimes black or reddish). Unlike ant debris, with which they can be confused, the piles do not contain fibres or parts of dead insects. Careful examination of the timber near the frass usually reveals a small hole (about 1 mm diameter). This may be difficult to find as it is often sealed when not in use. Sometimes infestations are discovered by accidentally breaking into a gallery in floor boards, window sills or other wooden parts of a building. Rarely, collections of termite wings may be found around windows or in the corners of rooms.
Fig 3. Frass and section of pine showing galleries
What to do
If evidence of drywood termite activity is found, collect a sample of the frass or termite wings. Where possible, collect and preserve several soldiers and forward to a scientific authority that has a termite specialist.
Prevention
Most of the preventative strategies employed against subterranean termites in houses do not prevent drywood termite attack. Drywood termites can enter a house by two means; introduced in infested second-hand timber (including furniture) or by flight. Thoroughly examine second-hand timber and furniture for drywood termite activity before taking it into a house. Prevention of entry by flight is more difficult. Most modern building designs, however, do not favour entry of drywood termites in this manner. In older houses on stumps, treatment of the lower surface of flooring with a suitable oil-based insecticide may be useful, especially where borer activity may act as a point of entry for drywood termites. Since drywood termites fly weakly, the rate of spread by flight is very slow. Therefore, when dispersal from a house occurs, adjacent houses are most at risk from attack. It is in your interest to acquaint your neighbours with the habits of drywood termites.
Fig 4. Fumigation of a large city building
Fig 5. Fumigation of a suburban house
Treatment of active infestation
Whenever drywood termite activity is suspected, send a sample for identification. The identification, extent and site of activity will help determine the appropriate treatment.
Cryptotermes brevis
The West Indian drywood termite is a notifiable disease under the Diseases in Timber Act. Necessary treatment of this termite is presently undertaken and supervised by the government, without cost to the householder. Tent fumigation of buildings is used to eradicate this pest (Figures 4 and 5). Strict supervision and specifications ensure set standards are maintained.
Other species of economic importance
Where other species are involved, you may have several options depending upon the extent and site of activity. The extent of the infestation can be found by 'sounding' the timber with a blunt instrument, such as the handle of a screw-driver or chisel. Areas of infested timber sound hollow when hit.
Badly damaged timber should be removed and burnt and replaced with non-susceptible or suitably pre-treated timber. Areas with minor damage can be treated by drilling into the galleries and injecting an oil-based insecticide. All infested areas must be treated to obtain maximum penetration into the galleries. Unpainted or bare surfaces may then be brush-treated or sprayed with the oil-based mixture. Poor penetration can be expected with any insecticide where the surface to be treated is painted.
Where the timber is vertically oriented, for example, VJ wall boards and timber house-stumps, the injection should be as close to the top as possible. Distribution of the chemical is thereby assisted by gravity. A schedule of two treatments in the first six months and then a treatment each four to five years may be appropriate, depending upon circumstance. The success of a treatment may be difficult to assess as frass may continue to be expelled due to movement of the timber.
Tent fumigation may be very effective against infestations, but it confers no immunity. Its application for general timber pest management is not recommended because cheaper, safer, more persistent and less disruptive alternatives are appropriate.
Living trees
Drywood termites in living trees usually do not pose a threat to the tree. Cryptotermes primus and C. domesticus can attack both the dead wood of living trees and timber-in-service. Where drywood termite activity in a tree is suspected, collect a sample of frass and, where possible, several soldiers. Label and dispatch the samples as described above. These reports and collections will also help in defining the distribution of both native and introduced drywood termites.
Infestations in trees may be managed by tree surgery in which the affected tissue is removed and the wound allowed to dry and heal. Oil-based insecticides should not be applied to the wound as these may adversely affect the tree. Removed wood should be burnt.
Summary
Drywood termites cause considerable damage to timber structures in coastal areas and adjacent tablelands in Queensland. Each of the four introduced species has a restricted distribution within this zone, but the native C. primus is more widespread. Other native species are of little economic importance. Knowledge of the habits of drywood termites and regular inspections of buildings and houses are the best insurance against these pests. The West Indian drywood termite is a notifiable disease and treatment, at present, is undertaken and supervised without cost to the householder. Therefore, identification of species is recommended before treatment is implemented.
Source of information
Peters, B.C., J. King, & F.R. Wylie. (1996) Pests of Timber in Queensland. Queensland Forestry Research Institute, Department of Primary Industries, Brisbane, 175 pp. Available from Queensland Government Publications
Related DPI&F notes
Anobiid beetles in timber in Queensland
Borers and the householder in Queensland
Powderpost beetles in Queensland timber
Subterranean-termite-baiting systems
Subterranean termite infestation in buildings
Subterranean termites in Queensland
Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Department of Primary Industries and Fisheries Queensland has taken all reasonable steps to ensure the information in this publication is accurate at the time of publication. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter.
Last updated 24 January 2007
