Borer Treatment

Timber Pest Inspections & Control

Geelong, Lorne, Surf Coast, Apollo Bay, Bellarine & Surrounding Areas

There are several types or wood borers (or “timber borers”) in Australia. Some can cause more serious damage than others so it is important to identify them.

Borers are actually the larval form of certain types of beetles. They damage wood by tunnelling at the larval stage for food or leaving an emergence hole on the surface of the wood after becoming a beetle. These emergence holes are quite visible and are usually the first signs of an active infestation of wood borer.

Treatment for wood borers includes replacing unsound timber, preferably using non-susceptible timber. Sound timber needs to be monitored to see if the infestation is active.

Active infestation can be treated – please contact us for a quote on a treatment program.

Of course, ideally  we would expose and destroy timber pests before they do any damage. Timber Pest Inspection Reports start from $325.

About the Borer Woodworm (Anobium Punctatum)

Courtesy of: Tim Hutton

Anobium Punctatum, generally known as the common furniture beetle or ‘woodworm’, has been perceived to be the main cause of damage to timber in the UK over the last 100 years. During the last 50 years, insecticidal treatments have been widely marketed and used to ‘treat and preserve’ timbers in buildings thought to be at risk from this organism. The perceived risk of woodworm infection and decay has become so integral to the culture of property management and building repair in the UK that most buildings which are more than 50 years old have been treated at least once, and many have been treated repeatedly on each change of ownership. This became almost automatic as mortgage lenders became convinced of the requirement for ‘guarantees’ that woodworm was not active in a building before issuing loans.

IDENTIFICATION AND LIFE CYCLE

Anobium punctatum is one of a large number of beetles that have evolved to exploit the cellulose in timber in temperate climates. It occurs naturally in the wild in the temperate woodlands of northern Europe and may have colonised other similar temperate environments, particularly in New Zealand and the east coast of North America. The adults are small oval brown beetles approximately 4-6mm long. When viewed from above, the head and eyes are invisible beneath the thorax and the wing cases have relatively straight parallel sides rather than an oval or round appearance. When viewed under the microscope, the surface of the wing covers are seen to be covered with fine yellowish hairs and longitudinal rows of pits are visible. The antennae should be visible extending from beneath: these have eleven segments with the last three segments enlarged so that these three together are longer than the combined remaining segments.

The adult beetles emerge from infected timber in the spring, generally between May and August in the northern
hemisphere, leaving a small round hole of approximately 1-2mm in diameter on the surface of the wood. The adult beetles mate soon after emergence: first, the female beetle appears to seek out suitable timber to lay her eggs and for the larvae to feed on, and the male then seeks out the female by tracking the pheromones she releases, giving preference to visual cues for standing timber. The adult beetles then die without causing further damage to timber.

The small pearl-like eggs may be seen with the naked eye in clusters of up to 50. These are only laid on dead timber where the bark has been removed and where there are suitable egg laying sites, such as cracks, crevices, exposed end grain or previous emergence holes. Anobium punctatum specialises in infecting the sapwood of temperate softwoods and hardwoods that have been dead for at least five years, but may also infect the heartwood of timbers such as beech, birch, cherry, alder and spruce, or timbers that have been modified by fungal attack. The eggs of Anobium punctatum generally hatch within six to ten days under suitable environmental conditions. As with many other insects, the majority of the lifecycle of Anobium punctatum is spent as larvae. These are greyish white in colour with a narrow dark band over the mouth parts and grow to about 6mm long. The front part of the body appears relatively thick or hunched and has three pairs of visible legs. The rear section of the body is thinner, with a rounded tail-end. There are transverse bands with two rows of spinules on the first six segments and a single row of spinules on the seventh segment. In the wild, the larvae generally spend a year excavating tunnels usually approximately 1-2mm in diameter and generally parallel to the grain of the timber. These tunnels are backfilled with the residues of the timber consumed, forming a cream-coloured powdery material consisting of lemon-shaped pellets when viewed with a microscope, which may feel gritty to the fingers if relatively fresh. It is in the larval stage that Anobium punctatum causes most of the damage to timber.

 

In the wild, after growing for about a year, the larva of Anobium punctatum forms a cell just below the surface of the wood where it pupates into an adult in approximately two to three weeks. The size of the larva when it pupates and the size of the adult and the resultant emergence hole will vary depending on the size of the larva at that time, and presumably on the relative suitability of the food and environment available. Anobium punctatum appears to have a preference for dead standing timber with the bark removed and only thrives under the conditions produced by the temperate climate of northern Europe. It therefore does not tolerate relative humidity below 60 per cent or timber moisture equivalents below 14 per cent, nor will it tolerate saturated timber and it will not thrive in temperatures much above 30°C.

THE CONDITIONS REQUIRED IN BUILDINGS

The environmental conditions within an occupied building are generally unsuitable for Anobium punctatum to lay its eggs, consume timber and complete its lifecycle. This is because it generally requires a relative humidity above 60 per cent for the eggs to hatch or for pupation to its adult form to occur. The sharply fluctuating and relatively low moisture contents of timber elements in an occupied building and the intermittent high temperatures that occur in many structures also prevent or restrict the growth and development of Anobium punctatum. For this reason, the insect generally requires at least three years to complete its lifecycle, not one, and the conditions required for it to flourish are only found in external structures such as outhouses and agricultural buildings, or in parts of a structure subject to chronic damp problems. However, it should be expected that at least 50 per cent of buildings in the UK have had some prior infection and decay by Anobium punctatum, and it is believed that nearly every house in New Zealand which is more than 15 years old has been subjected to some prior infection or decay. It has also been noted that almost every building in Germany has been infected.

Timber structures in buildings in the UK likely to have been infected and partially decayed by Anobium punctatum at some time are those which have been subjected to damp conditions persisting for over five years, but not subject to liquid water penetration. Typical causes include condensation and/or high relative humidity, generally as a result of inadequate ventilation and cold-bridge condensation. Poorly ventilated basement and sub-floor structures, particularly the cupboards and voids beneath staircases, and timbers in poorly ventilated roof voids are therefore often found to have been infected at some time. The latter may be a particular problem in the north and west of the UK due to the relatively high moisture levels and reduced summer temperatures in roof structures compared to the south and east. Similarly, it is not unusual to find evidence of past woodworm infection and decay around poorly ventilated and insulated skylights or roof hatches, and in floor structures of bathrooms and kitchens subject to intermittent water penetration and/or high relative humidity levels. Despite the above, infection by Anobium punctatum today is rarely active or structurally significant, and heating and ventilation on occupancy will generally prevent further infection or decay.

Factors preventing infection and decay by Anobium punctatum in buildings are generally the absence of suitable sapwood timber in persistently damp conditions, and the absence of suitable cracks, crevices or holes for deposition of eggs on finished timber surfaces. Historically, the most significant damage by Anobium punctatum was perceived as being the decay of furniture, hence its common name, the furniture beetle. This is probably because in the past furniture was commonly made of cheaper and less durable local timber such as beech. The relatively high proportion of sapwood in country-made or ‘bodged’ timber furniture would also be vulnerable to Anobium punctatum, and the cracks and crevices formed at the joints in furniture also make it vulnerable to infection and failure at these points. It is not unusual to find decay to the bottom of the legs of poorer quality antique furniture due to the relatively high proportion of sapwood on turned elements in these areas, and because legs were often in contact with damp solid floor structures.

As a food source, timber is generally deficient in available nitrogen and this is often a major restraint on the growth of organisms relying on timber as a primary food source. It is for this reason that pre-digestion by fungi or bacteria often makes timbers more vulnerable to decay by other organisms and why contamination with highly nitrogenous materials makes timber more vulnerable to decay. However, the glues used for the construction of furniture in the past were often based on animal products such as horn and contained high proportions of proteins and other nitrogenous materials. Their use in the joints of furniture therefore made the glued timber particularly attractive and vulnerable to infection and decay. More valuable furniture was often made with the heartwood of durable timber such as oak or, later, tropical hardwoods. These are generally resistant to infection and decay by the larvae and may represent the majority of antique furniture surviving today.

 

IDENTIFYING ACTIVITY

In most cases, infection and decay by Anobium punctatum is first suspected due to the discovery of typical small emergence holes in vulnerable timber elements and this is often the only symptom, resulting in unnecessary treatment. Diagnosis of Anobium punctatum infection has even been mistakenly made on the basis of holes made by drawing pins or from other causes. With experience, it is possible to distinguish emergence holes of Anobium punctatum from those of other woodboring beetles and from other causes. However, even when emergence holes are correctly identified, these are by definition the result of past infection and decay, as they are made by the adults emerging and leaving, so may no longer be active. More recent emergence holes can be distinguished by the This timber was infected by active Anobium punctatum and shows the typical holes and deposits of gritty yellow frass, which can be shaken out of old emergence holes by vibration from road traffic or building works long after infection has ceased to be active.

Paint finishes or special paper strips may be applied over suspected areas of Anobium punctatum infection to identify new emergence holes as these appear. Activity may also be monitored by trapping emerging adults with
electric UV flying insect traps, and by checking cobwebs, particularly around window openings, for caught adults.
Similarly, pheromone traps are widely available commercially to allow emerging adult males to be trapped. All of these techniques may be useful for general monitoring of activity and may also help reduce the risk of re-infection. However, it may not be possible to determine where the adults have been emerging from. The deposition of quantities of fresh gritty frass from the emergence holes may sometimes indicate active infection. However, frass may often be found coming out of emergence holes in previously affected timbers many years after active infection has ceased. This may be due to vibration caused by heavy traffic on adjacent roads or building works elsewhere on the structure. Again, the appearance of freshly deposited frass around emergence holes has often been the justification for extensive remedial treatments in the past, even when the infection by Anobium punctatum has been dead or inactive for many years.

Searching for live Anobium punctatum larvae within timber is generally destructive, and surprisingly few larvae may actually be found. It is possible to use highly sensitive piezoelectric microphones embedded in the timbers to monitor activity, but this is not yet the basis of an effective diagnostic technique for use in the field. Similarly, it is possible to identify recently produced frass using immunological or genetic techniques. Again, this is not yet the basis of a cost-effective field identification technique. In practical terms, the likelihood of significant Anobium punctatum infection is relatively easy to assess, in that if the deep moisture content of the timber is below 12 per cent, it is too dry for infection and decay to occur, while if the moisture content is between approximately 16 and 30 per cent it is possible, even if infection and decay is not present at the time of investigation. If a deep moisture content of 16-30 per cent is found in the sapwood of vulnerable timber, then an assessment has to be made whether this moisture content is likely to persist for over two years. If this is the case, then appropriate remedial measures should be considered. In all cases, a risk assessment of the significance of active or past Anobium punctatum infection must be made; for example, there may be a high risk that active Anobium punctatum may be present or may occur, but a low risk of structurally or aesthetically significant damage occurring given the low significance of the vulnerable sapwood component of the affected timber. Alternatively, there may be a very low risk of continuing active Anobium punctatum infection, but a high risk of structurally significant decay having occurred in the past, for example, to joints in vulnerable timber structures or to timber supporting a valuable finish. In the last 100 years, infection and decay of new furniture by Anobium punctatum has become less common. This is probably due to the increased use of tropical hardwoods and the application of Paper patch fixed to timber to detect fresh emergence holes: this can be a cost-effective way of monitoring activity by Anobium punctatum and the efficacy of measures to dry the structure.

Active infection and decay is therefore generally confined to older furniture, particularly that which has been stored for at least part of its life in damp, poorly ventilated and unheated conditions. In this context, it should be realised that a localised low level of Anobium punctatum infection may persist in infected timbers for many years after original infection, particularly under conditions which are generally unsuitable for the beetle to complete its life cycle. Adults may therefore eventually emerge from previously infected timber many years after original infection, with little or no risk of further infection or decay. This should not be mistaken for evidence of a sudden outbreak of active infection and decay.

Types of Wood Borers

Lyctid borer (Powder post borer)

  • Produce a very fine powdery dust, similar in consistency to talc
  • Attack the sapwood of certain hardwood timbers
  • Cause serious structural weakening in timber that has a high sapwood content

Treatment of lyctid borer is often unnecessary in the southern parts of Australia, where grading rules in sawmilling restrict the amount of sapwood contained in framing timbers. Timber over five years old is unlikely to contain these borer as they will have exhausted the food supply. If decorative timber becomes unsightly then treatment described below can be applied.

Anobiid borer

Produce a gritty ‘salt like’ dust. There are many different species of this borer, but two significant ones are:
Anobium punctatum (Common furniture beetle)

  • Attack furniture, structural timbers, flooring and decorative wood work
  • Prefer old, well seasoned timber, especially softwoods such as Baltic pine or New Zealand white pine
  • Attack some hardwoods, especially blackwood and imported English oak. Australian eucalypts appear to be immune
  • Prefer cool, humid conditions

Calymmaderus incisus (Queensland pine beetle)

  • Commonly found in Queensland
  • Attack softwood timbers such as Hoop pine and to a lesser extent Bunya pine and New Zealand white pine
  • Attack to timber in dark sub-floor areas is common

Good drainage and sub-floor ventilation will help reduce the risk of attack to softwood flooring timbers from these species.

About Termite Watch

Termite Watch is an Australian pest management company established in 1997. We are family owned and run. Based in the coastal town of Lorne southern Victoria, we service Melbourne, Geelong and the Great Ocean Road to Apollo Bay.

We offer pest control solutions that minimise the use of pesticides and the effect these can have on the environment.

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Our Service Area

Our service area includes Lorne, Torquay, Geelong, Anglesea, Aireys Inlet, Wye River, Apollo Bay, Kennet River, Bambra, Winchelsea, Colac, Deans Marsh, Ocean Grove, Barwon Heads, Drysdale, Clifton Springs, Forest, Gellibrand, Marengo, and Lavers Hill.

Commercial Pest Control

Termite Watch offers both residential and commercial pest control services. Our commercial pest control service encompasses a complete suite of solutions, suitable for any type of business. We offer:

  • Full programmes for Rodents and/or insects.
  • Affordable 6 or 12-month contracts.
  • Servicing Retauraunts, Hotels and Apartments.
  • Tailored packages for Holiday Rentals and Units.
  • Discrete control measures and programmes.
  • Estimates and Quotes performed free.

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