Gulf Construction Online - Masa employs tough pest management

Timber & Plywood

Al Shieshakly.

Masa employs tough pest management

Mousaied S Al Shieshakly* takes a closer look at the insects that infest wood and timber and provides guidelines on how to prevent the risk.

01 May 2010

ABOUT a third of each year’s forest crop is used in construction and the demand continues to rise. A significant portion of this rising demand can be met by increasing production, reducing waste during processing and protecting commodities in service from deterioration.

Efficient pest management greatly helps in protecting our existing commodities as termites and other insects infest and seriously damage wood.
Many of these, such as the various bark beetles, powder-post beetles and round- and flat-headed borers are found alive frequently in unseasoned wood. The pest management professional is usually most concerned with those insects that damage seasoned lumber. The characteristics of the damage done to wood by these insects are generally sufficient evidence to identify the insects to their family, but positive identification to genus and species requires examination of the insect itself.

Beetles & termites
Among the many different kinds of insects that attack wood and wood products, the destructiveness of powder-post beetles is second only to that of termites. They infest and re-infest dry seasoned wood, with the interior of such wood (usually the sapwood only) being completely riddled with holes or galleries and packed with wood dust or frass. Pinhole openings often called shot holes perforate the surface of infested wood. Both hardwoods and softwoods are attacked, although the family Lyctidae is specific to hardwoods such as ash, oak, fir, and some maple.
Powderpost beetles infest flooring, studs, girders, and other parts of the buildings, as well as lumber, crating, panelling, furniture, tool handles, gun-stocks, and many other wood articles. Structures are sometimes built with infested lumber. Beetles that attack softwoods often fly into crawl spaces beneath buildings and lay eggs on exposed wood there. The first evidence of infestation is usually piles of very fine sawdust on or beneath wood and small holes in the wood surface. At that point, infestation may have been present from three months to three years or more, depending on the species involved, environmental conditions, and type of wood attacked. In hidden areas such as crawl spaces, serious damage may be done before the infestation is discovered.
For termites, treatment procedures for the drywood species consists principally of structural fumigation or wood treatment. The direct wood treatment method (used for local treatment, such as wood injection) should be used only in the case of limited infestations. Extensive infestations should be controlled by fumigation or heat. Treatment of the entire structure usually involves fumigation, while partial (compartmental) treatments can be accomplished with heat.
Structural fumigation is done with sulfuryl fluoride (Vikane) as an example. Vikane has the advantage of rapid and uniform dispersion within the temperature range for climates where drywood termites are found. Such fumigations should be done only by professional thoroughly trained in the use of fumigants.
Direct wood treatment involves the preparation for the use of liquid, aerosol or dust formulation, where holes are drilled into the infested timbers through the termite galleries. Insecticide is then forced through these holes, to be dispersed through the galleries. The use of liquid insecticides, such as borates (disodium octaborate tetrahydrate), controls drywood termites when active galleries and access points in infested wood are pressure injected. Drione is an example of a dust used. Dust should be injected into the termite galleries in small amounts as excess dust will plug the galleries, and the termites will wall off and thus isolate these areas. When treating limited infestations, aerosol and liquid formulations are frequently used. After an insecticide has been injected into wood, the openings should be plugged with wooden dowels.

Other methods
Other methods of drywood termite control being used on a limited basis and still need further research and development, include heat, fumigation, extreme cold, electrocution and microwaves.
For the heat treatment, structures are tarped and hot air generated by specialised heaters is blown into the covered structure or a section of the structure, until temperatures reach a constant 140 to 150 deg F. Fans are used to circulate the heated air and to achieve a uniform temperature within the area treated for 35 minutes to kill the termites. Thermocouples, or temperature probes, are used to selectively monitor heated timbers which will reach 120 deg F. This can be quite an expensive process for treating an entire building, due to the prolonged time needed to achieve the needed temperature and is more practical and economical for smaller areas with exposed timbers, and where items that may be damaged by heat can be easily removed.
Liquid nitrogen has been used to create -20 deg F temperatures for at least five minutes for localised treatment of termites. Only limited areas can be cooled simultaneously to this temperature. Covering the surfaces surrounding the treatment area with insulating mats increases the efficiency of the treatment and reduces condensation. Many variables influence the efficacy of cold treatments; thus, future evaluation is needed.
Electrocution by delivering high-voltage and high-frequency energy to targeted sites in timbers, using a handheld unit, has been tried. Spot treatments for drywood termites or powderpost beetles are undertaken by delivering the electric charge to infested wood. Theoretically, the termites will be shocked and killed by the passing current. Drilling holes into wood and/or inserting copper wire into drill holes facilitates the passage of the current into infested areas. The devices are designed to avoid structural damage and electrocution of the control specialist. As with all other localised treatments, identifying all infested areas within a structure is essential to eliminating all the termites.
Units producing electromagnetic energy at microwave frequencies have also been used on a spot-treatment basis to eliminate drywood termites from structural timbers. The high-energy zone is very limited, so heat-vulnerable items usually do not need to be removed from the structure. However, the distance limitation on microwave transmission means that treatment areas are much localised; thus, infestation and their boundaries must be precisely identified to achieve control.
Heat fumigation, extreme cold, electrocution, and microwaves involve complex technologies that control specialists in some geographic areas will want to consider. Consumer preferences, applicator-safety, liability, economics and efficiency and effectiveness are some of the aspects each company needs to consider in deciding which control methods best suits their needs.
There are number of measures that should be considered for the prevention of non-subterranean termite infestation. All lumber, especially second-hand lumber should be carefully inspected for evidence of infestation before being used for construction purposes. Infested lumber should be treated, and moist or moisture-damaged wood should not be used. In existing buildings, all doors, windows (especially attic windows), and other ventilation openings should be screened with 20-mesh non-corrodible metal wire cloth. Screening will prevent winged termites from entering areas where colonies can be established. Chemically-treated wood will also prevent attack.
Lumber treated with wood preservatives can be purchased in many areas. An appropriate number of coats will fill many of the cracks and openings into wood. Larger cracks and joints can be filled with putty or plastic wood. While the use of steel, concrete, brick, or stone in construction instead of wood offers the best protection against non-subterranean termites, the use of these materials will not prevent attack of wooden materials inside unless all entryways are properly sealed.

Subterranean termites
Millions of dollars are spent every year on replacing termite-damaged timber and plywood and termite control. Termite management is currently undergoing an unprecedented change with new researches and technologies being introduced. Various control methods being used include termite baits, monitoring systems, aerosol application, timber and plywood preservation and termite proofing, termite-detecting electronic devices, and various electronic and electrical and physical methods.
There are certain factors that are favourable for termite attacks and make buildings more vulnerable and thus preventive and corrective measures are best applied during or before a building is constructed. The following conducive conditions can be managed to prevent or make the structure safer from termite infestation.
• Wood-to-ground contact: Most of the termite infestations inside a building can be traced back to some contact of wood with the ground, which provides food, entry point, moisture and easy access within the building. To prevent this, wood sidings, windows, and door frames should be at least 15 cm above the ground level. Wooden posts, door frames and stair carriages should never penetrate the concrete – they should be cut from the bottom and be supported by 15 cm concrete blocks.
Where it is not possible to remove the contact of wood with the soil, the soil must be treated with termiticide and the wood treated with wood preservative.
• Wood debris: Any cellulose materials below the soil attract foraging termites. Hence, stumps, boards, scrap wood, paper and cardboard boxes should be removed from under and around the building. During the construction phase, wood, timber or compost piles must not be placed near the foundation as it may provide a hidden route to termites.
Control of subterranean termites can be accomplished very easily in most cases. It requires removal of wooden debris from around or under the structure, correcting conducive conditions such as excess moisture, earth-wood contact and finally a termiticide barrier introduced into the soil around and/or under the structure.

* Mousaied Al Shieshakly is the owner and general manager of Riyadh-based Masa Establishment for Pest Extermination, Maintenance and Contracting, which this year marks 30th years in the pest control industry, having successfully treated thousands of dwellings, artwork, museums, antiques, wooden frames and other valuable materials from wood-infesting insects.