The subterranean termite Reticulitermis flavipes (Kollar) is probably the most destructive and widely distributed species in North America. This species has acclimatized to southern Ontario to such a degree that 27 municipalities report some degree of infestation.
Subterranean termites were first reported in Ontario at Point Pelee in 1929. It has subsequently been reported in Toronto (1938), Windsor (1950), Kincardine (1954), Oxley (1955), Amherstburg and Dresden (1968) and Guelph (1975). Presently in Metropolitan Toronto, the termite infested area extends through a radius of approximately 30 kilometers.
In contrast to termites, carpenter ants do not eat wood and other cellulose-based materials, but instead simply excavate living quarters and hatching chambers that are usually quite limited in extent.
Powder post beetles only do significant damage when multiple generations continually re-infest the same piece of wood. Also, powder post beetle damage is restricted to hardwoods, and since most structural framing is made of softwood lumber it is rarely attacked by these insects.
Carpenter ants, found in the Pacific Northwest, the northern Midwest, New England and southern Canada, are distinguishable from termites by their dark colour, narrow waists, elbowed antennae and when present, the large front and small rear wings. Carpenter ants rarely attack sound dry wood, preferring damp wood, foam or cellulose insulation, and do not use wood for food. They are more easily spotted than termites as they expel wood fragments from their excavations, and forage for food in the open. The presence of carpenter ants may indicate moisture problems in the building as they generally prefer already rotting wood.
Several species of powder post beetles are to be found in the U.S. and Canada. They vary in length from 1/16" to 3/8", but generally have flattened bodies, a prominent head and segmented antennae. True powder post beetles attack only hardwoods (particularly oak, hickory, ash, walnut and cherry) but other species of wood boring beetles attack both hardwoods and softwoods.
Powder post beetle larvae cause millions of dollars worth of damage in the US and Canada annually, and are almost as destructive as termites. Adult beetles lay their eggs in the surface pores of wood. The larvae bore into the wood as soon as they hatch. Living in the wood, they create tunnels called galleries as they eat their way through the timbers. When the larvae are nearly full grown, they bore near to the surface of the wood and pupate. The adults bore out through the surface soon after pupation, pushing a fine powdery wood dust, usually a copper to yellow-gold in color, out of the wood as they emerge.
Termite Characteristics:
Subterranean termites are social insects, feeding on cellulose and living in colonies in the soil. These colonies are close to moisture, and can be readily relocated due to temperature or other environmental changes. Termites travel through soil, in wood itself, or through shelter tubes.
In the termite colony there are generally several generations present. The colony is made up of several castes (forms) (larvae, nymphs, secondary and primary reproductives, soldiers and workers), who carry out specific duties or functions.
The female reproductives may thousands of eggs. These eggs hatch and pass through an immature stage (larvae) before finally differentiating into either a worker, soldier or reproductive caste.
The primary female reproductive (the queen), is very rarely found in Ontario, whereas secondary reproductives in the colony carry on extensive reproduction.
The two wingless non-reproductive castes consist of the soldiers and workers. The soldiers defend the colony from outside attack, while the workers carry out all duties except defence and reproduction. For example, the workers feed the reproductives, larvae and soldiers, care for the eggs, and construct tunnels and shelter tubes. The soldier caste consists of sterile adults with large heads and pincher-like mouth parts. These soldiers make up 2-3 % of the total colony.
There are three known methods by which a new termite colony may be established.
The first method, common in the warmer climates of the southern United States, is called swarming. This occurs usually in spring, when large numbers of winged primary reproductives (alates) (top photo) emerge from a colony, fly a very short distance, mate and then establish a new colony. Although alates are found in Ontario, rarely do they swarm.
The second method is called “budding”. In this method, when a colony becomes sufficiently large, or a portion of a colony becomes separated from the main colony, new secondary reproductives are formed from larvae or nymphs and the nucleus of a new colony is established.
The third method of dispersal is through infested wood or soil being transported to a new location. As few as 15-40 larvae or nymphs contained in the infested material may moult to become secondary reproductives and begin a new colony.
The worker termites are white in colour and approximately 6mm (1/4 inch) in length. Their antennae are straight (not elbowed) and the body is not narrowed at the waist, which distinguish them from ants. They have chewing mouth parts and are responsible for foraging and feeding the dependent members of the colony. The hind gut of the worker contains protozoa (single-celled animals) which assist in breaking down cellulose into its component parts which are digestible by the termite. The worker termite causes the structural damages.
Soldier termites are similar in size and colour to workers, but have an enlarged brownish coloured head with large modified mandibles (large biting jaws), used for defense.
Termites have a very thin cuticle (skin) and are subject to rapid desiccation (drying out) if exposed to the environment outside their enclosed habitat. In order to maintain a highly controlled environment, termites must live in a closed system. Colonies in wood are always contained within an outside shell of cellulose material. In this way, they are protected from exposure to the outside.
Often shelter tubesconstructed of soil particles cemented together by excrement or secretions from the mouth are used to connect the outside soil to a building and for crossing a concrete or metallic portion in a structure. The presence of a shelter tube is generally the first physical evidence of a termite infestation.
Damage to Wood:
The subterranean termite is very closely associated with the soil, which is its main source of life-sustaining moisture. Termite food consists of cellulose obtained from wood and wood products. Decaying damp wood is preferred but termites are also able to feed on sound, dry lumber.
The series of galleries (area hollowed out) created by termites in wood give a honeycomb appearance. These galleries follow the wood grain. Interior galleries contain greyish specks of excrement and earth, called frass.
The damage to wood is usually not noticeable on the surface, as the termite avoids exposure to air. Therefore the exterior surface of the wood must be stripped away to see the damage.. Termites do not reduce wood to a powdery mass, or push wood particles to the outside as do some wood-boring insects, such as carpenter ants and powder post beetles.
Evidence of an Infestation:
The presence of shelter tubes over the surface of foundation walls is the primary sign of a termite infestation. These tubes are 6mm (1/4 inch) to 12mm (1/2 inch) wide, and can extend many centimetres in length until wood is discovered. These tubes protect termites form the drying effect of air, and maintain the termites’ contact with the soil.
What you can do to prevent an infestation of termites:
Conduct a complete and thorough removal of all scrap wood and wood products from around the property.
Improve the water drainage around your property. If the soil is constantly moist, optimum conditions are provided for the termites. Repair eaves trough, slope concrete walks away from the house and repair all leaks.
Proper ventilation is essential to eliminate moist conditions. The main areas of concern are verandas and crawl spaces. The amount of ventilation will be variable according to regional and local factors, and must meet building standards.
Break the wood-soil contact. To little clearance between the soil and wooden structures often results in all of the physical requirements for a termite infestation being met (moisture, decaying wood, and food readily available). A general rule is that there should be a 45cm (18 inch) clearance between the soil and lowest horizontal members of the structure. If wooden lattice-work is used around verandas, there should be a space of 50 – 75 cm (20-30 inches) between the soil and this lattice-work. Other problem areas include veranda and basement steps, where the wood is in direct contact with soil.
Termites often enter buildings through cracks and holes and expansion joints in foundations. Spaces around piping and wiring are also points of entry. These openings may be filled with either roofing-grade coal-tar pitch, sealers or similar commercial caulking products.
Avoid storing fire wood directly on the ground. Care should be taken when obtaining infesting material (such a soil and discarded lumber) from known termite areas.
Suppression of Termites:
Suppression refers to measures intended to reduce and eventually eradicate termites from infested materials in a designated area. Suppression methods include systematic location and destruction of colonies not associated with buildings (such as in street trees), systematic inspection of wood products leaving an infested area to quarantine the infestation, burning of infested lumber and heat treatment of reclaimed lumber.
Site Management:
Careful site preparation and clean-up can do much to discourage the colonisation of a new or existing building site by termites. Where forest or orchard land has been cleared, tree roots must be completely excavated and removed along with any other buried wood.
During construction, it is important that:
- stumps be removed
- all wood and other cellulose containing construction debris be removed from the site
- survey pegs and concrete formwork be removed and disposed of properly, rather than buried or encased in concrete
- excavation spoil is not used to fill in under porches or steps
- site grading drains water away from the building
- non-treated wood elements be raised from the ground according to the following table:
Chemical Treatment:
Before any chemical treatment can be done all wood in direct contact with the soil must be removed from the property.
Conventional treatment for termite control requires the services of a licensed exterminator. Several firms in Ontario are qualified, and your Yellow Pages or a Local Search will assist you in locating companies in your area.
Chemical treatment takes approximately one full day, and involves four distinct phases:
Treatment around the exterior of the foundation walls as deep as the footings.
Treatment under the basement floor adjacent to the foundation walls and any supporting pillars.
Injection of pesticide into the basement wall itself.
Finally, all exterior areas where trees, sheds or fences are located are to be treated.
Soil Barriers:
The environmental and health risks associated with chemical usage have led to the withdrawal of several termiticide products from the market. Barriers consisting of a layer of precisely sized sand or crushed stone below and around foundations are an alternative means of preventing termite entry.
Building Design:
Foundation walls and slabs should be designed to inhibit the entry of termites into the building, and to facilitate inspection for shelter tubes. Sheet metal and steel mesh barriers properly designed and installed, are also an effective means of control. Wood products and other building materials should be selected with regard to termite resistance.
Bait, Trap and Release:
Baiting involves placing bait tubes or traps in the ground at intervals around a building -several dozen for a typical house. Pieces of untreated timber or other cellulose-based material are inserted into these tubes as bait for termites. The tubes are monitored and, when termites are observed feeding on the bait, it is replaced with treated bait containing a chemical that the termites then carry back to the colony. The chemical is slow acting, so termites are unable to associate its source with its effects. Over a period of several months, the entire colony may be destroyed.
When no further activity is observed in the bait stations, treated bait is removed, and replaced with untreated bait. Monitoring continues on a regular basis, and the procedure is repeated as necessary. Several companies offer products and services that are variations on this method of site treatment, although baiting is still a relatively new approach for termites.
Points to Remember:
- A new infestation of termites may be introduced through one small piece of infested wood containing as few as 15-40 termites.
- Any such infested wood must be destroyed or treated in an approved manner before disposal.
- The first indication of a termite infestation is the presence of shelter tubes.
- The secondary indicator may be the collapse of damaged wood.
Checklist for Staying Termite-free:
If you live in a termite-prone area, assess your hazard exposure and use the information here to develop a termite management strategy that includes some or all of the control measures presented. Termite management is an ongoing process that with constant vigilance and maintenance can save a lot of trouble, worry and money.
- have a professional inspection done every year
- keep termite habitats away from the immediate area around the building
- clear or relocate buried wood such as tree stumps, firewood, scrap wood, cardboard boxes and plants
- be vigilant for foundation settling or shifting that could open new paths for termite access
- quickly fix any roof or plumbing leaks so that moisture does not enter the building envelope
- keep roof gutters in good repair and ensure they direct water away from the building
- maintain the integrity of physical barriers such as sand or mesh - do not lay soil or mulch over the barrier, or let roots grow through it
- repair poorly ventilated bathrooms, leaking pipes, clothes dryers and air-conditioner condensation leaks that result in termite-attracting moisture accumulation
- do not store wood, cardboard boxes or other cellulose-based material in crawl spaces
Sources of Information:
- Canadian Wood Council
- Ontario Ministry of the Environment
- University of Toronto, Urban Entomology Program
