KNOW YOUR ENEMY

Termite behaviour

Termites are good at predicting weather changes. Even before a heavy warm-season downpour begins, swarms of the reproductive caste termites (alates) are released from the nest and fly away to form new colonies. Fortunately, of the millions that set out, only an occasional pair succeeds in finding a suitable site, and many of these are taken by predators or die by desiccation. Warm humid weather conditions are favoured for the short flights, which usually occur during the warmer months.

Once established and mature, the Queen termite can produce up to 2000 eggs a day! This represents a huge potential for ever increasing timber destruction, if conditions are right.

Main and often subsidiary nests are excavated underground or in rotted tree stumps and woodpiles, wherever humidity is high. Underground galleries are dug to search for wood. The galleries preserve the moist atmosphere of the nest, shield the termites from light and protect them from predators (largely ants). Their network of galleries can stretch for a hundred meters from the nest in search of food.

Where their galleries leave the ground (for example to feed on a house’s floor framing) the termites construct shelter tubes with the same properties as galleries. They are usually about 20mm wide and look like piled-up mud trails, being constructed of soil and fecal material, bound together with termite saliva. These mud shelter tubes are the best way of identifying termite activity. The tubes may be seen climbing up the walls between the ground and floorboards, or if your house has stumps, snaking over ant caps between stump and bearer.

Once new food is found, the colony can virtually excavate the whole of the inside of the timber, leaving only a honeycomb of tunnel walls and a thin outer layer which preserves the controlled atmosphere. The destruction can be devastating and may be remarkably quick.

A full statement may not be possible until after the termite treatment has taken place (for fear of disturbing their active workings and making treatment ineffective) but the expert should be prepared to make out a statement soon after the treatment has had its effect. Other experts such as the Archicentre Inspection Service may be needed to assess the structural repair needed for the house.BORERS

There are several types of timber borers in Australia, some serious and some not, so it is important to identify them if you think you have a problem. Borers are actually all different families of beetles. Some of the relatively harmless ones not needing any special eradicative treatment are pinhole borers, longicorn borers and auger beetles. Pinhole borers cannot survive in timber once it has dried out, so they normally leave before, or soon after, the timber is used for construction. You can identify them by examining their “flight holes” (the holes made when leaving the timber). These holes will rarely have borer dust (or frass) around them, since in most cases the insect is long gone or dead. They leave relatively few holes unlike the more destructive species shortly to be mentioned. Longicorns leave oval-shaped holes 6-10mm in size as they emerge from framing timbers or wall linings. They are not a serious structural problem because, unlike the more destructive species, they cannot breed in the timber and therefore cannot proliferate.

The size and shape of their flight holes makes this borer easy to identify. Auger beetles, again fairly harmless, are harder to distinguish from the more destructive Iyctid borers mentioned below. One way of telling them apart is that auger beetles leave far fewer flight holes since they cannot proliferate in the timbers, so are far fewer in number. However, differentiating them from Iyctids is not normally important, since if conditions are right for auger beetles, they are even better for Iyctid borers, so if one species is present, you will normally find the other.

Lyctid borers

Lyctids are very common in Australia and attack the sapwood of certain hardwood trees. Sapwood is the living band of wood around the outside of the tree. Each State has its own regulations limiting the amount of sapwood to be cut from felled trees, some States try to eliminate its use altogether, or require susceptible sapwood to be treated. In the southern States, Iyctid attack to the sapwood of framing timbers is common. But the amount of sapwood in a framing timber is usually small, so borer attack will not seriously affect the timber’s strength. And being out of sight, the borers will rarely be noticed. However, within three to five years of the house being built, Iyctids could be found in skirting boards and architraves and these are highly noticeable timbers. Because timbers like skirting boards are thin, they could in some cases be cut almost exclusively from the outside of the tree and be largely made of sapwood, food for Iyctids. So these timbers could be riddled with Iyctids. Lyctids can be recognised by their 2mm holes and large quantities of flour-like dust. Although not a problem structurally, they are certainly unsightly and have probably put the wind up more homeowners than any other single cause. If Iyctid attack is visible, you could replace the affected timbers. Otherwise, they do not need any special treatment.

Anobiid borers

Anobiid borers are more serious and attack softwoods, especially varieties of pine (although very rarely do they attack the common Pinus radiata). Like Iyctids, anobiids are widespread throughout Australia. The Anobium punctatum species especially loves Baltic pine, commonly used 40 to 140 years ago but still occasionally used for floorboards and weatherboards. The “Queensland pine” anobiid Calymmaderus incisus located from northern NSW and farther north has a similar love for Hoop pine. Anobiids tend to channel along the grain of the wood, making the odd 2mm pinhole and leaving large quantities of loose gritty dust with a texture of fine table salt. They are capable of eating for years and will happily chomp away anonymously under the carpet. Be suspicious if your floorboards get spongy as this is a common area for them to attack. You will probably first notice the floor feeling spongy at one end of a large room (like the living room) because a big floor area will deflect more noticeably. Also be aware that second hand or antique furniture, or old floorboards may contain borers, so examine such articles well before introducing them into the house. Anobiid damage must always be attended to. Homeowners have sometimes stopped infestation by removing all significant borer-infested timbers and replacing them with non-susceptible timbers, then monitoring the results. Such treatment is only worthwhile if sub-floor humidity is simultaneously reduced, because borers thrive in damp conditions. Humidity can be reduced by removal of debris, increasing sub-floor ventilation (cleaning out vents and possibly adding more) and draining damp soil where necessary.

In some cases Anobiid-infested timbers need chemical treatment. As with termite eradication, it is recommended that only currently licensed members of your State’s pest control association be contracted and that they should provide a written description of proposed treatment as previously outlined.