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 TERMITES
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
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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. To0 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.
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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
What does a termite look like, how big are they?
Here's a view of a termite soldier of approx. 8 mm in length (a little more
than 1/4") posing between centimeter marks on a wooden metric ruler.
Carpenter ants are somewhat larger, and darker in colour with a narrower waist.
(See second photo from top.)
Sources of
Information:
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