of termite infestations include swarming of winged adults
in the spring and occasionally autumn. A "swarm" is a group of adults that
leave their nest to establish a new colony. Swarming occurs when
a colony reaches a certain size. Emergence is stimulated when temperature
and moisture conditions are favorable, usually on warm days following
rainfall. Other signs of termite presence include "pencil-size" mud
tubes constructed over the surface of foundation walls, mud
protruding from cracks between boards and beams, and hollow
from infested wood when it is tapped, or extreme softness
when probed with a knife. Termites feed slowly and there
is no need
termites are social insects that live in nests or colonies in the
soil. Each colony consists of three forms or castes of individuals,
which are the reproductives, workers, and soldiers. Reproductives
can be winged (primary) or wingless (secondary). The latter are
found in mature colonies and serve as replacements if something
happens to the primary reproductives. Winged, primary reproductives
(alates) are coal black to pale yellow-brown, flattened and about
6 to 9 mm (1/4 to 3/8 inch ) long, with pale or smoke-gray to brown
wings. Secondary reproductives are white to cream-colored with short
wing buds. Workers are wingless, white to grayish-white with a round,
yellow-brown head and about 6 to 9 mm (1/4 to 3/8 inch) long. Soldiers
are also wingless and resemble workers except that they have large,
rectangular, yellowish and brown heads with large mandibles (jaws).
Swarmers have straight, bead-like antennae, a thick waist and a
pair of long, equal-length wings that break off easily. The presence
of winged termites or shedded wings inside a home are signs of a
soldier and worker
a typical termite colony, the king and queen are the only active
reproductives; they perform no other function. They are fed by the
other termites, and some have lived up to 25 years. A mature queen
can lay thousands of eggs each year. During the two-week incubation
period, eggs are tended by the worker termites. The nymph hatches
directly from the egg. Attendants feed nymphs regurgitated food
for the first two weeks, enabling them through molting to become
workers, soldiers, reproductives or supplementary reproductives.
As the reproductive nymph matures, its body lengthens and sexual
organs develop. The body turns black, eyes become functional, and
wings extend twice its body length. The worker nymph has no eyes
and is sterile. Its main function is to provide the colony with
food, usually obtained by eating the wood of buildings. The soldier
nymph develops a long, armored head and large jaws during its last
molt. The sole purpose of the soldier is to defend the colony against
enemies such as ants. All mature reproductives leave the colony
at the same time, usually in the spring and sometimes in the fall.
Swarmers are poor fliers and, when above ground, usually flutter
a few meters and fall. Swarmers, emerging outdoors from tree stumps,
railroad ties, etc., are usually not of concern and are in no way
an indication that the structure is infested. After dropping to
the ground, they shed their wings. Surviving males find compatible
mates and then burrow into the ground to become king and queen.
These termites live in nests underground and tunnel up for food,
which includes the wood of homes.
A very small
percentage of swarming termites survive to initiate new colonies.
Many are eaten by other insects, birds, etc. Likewise, swarms emerging
inside a structure usually never survive. However, they are an indication
of infestation nearby. Workers need high humidity to survive and
will carry mud up into the wood where feeding to maintain a 97 percent
relative humidity. Termites have the ability to move their colony
up and down in the soil to find the optimal temperature and moisture
conditions. Workers build mud tubes from the soil to the wood in
structures on which they feed. Termites can feed on wood since they
have protozoa in their alimentary tract (gut) that digests cellulose,
the basic component of wood. Workers prefer to feed on fungus-infested
wood, but can feed equally well on undamaged wood. Workers secrete
food material from their mouths and anuses to feed the reproductives
In most cases,
once a termite infestation has been found, control measures are
best accomplished by a professional pest control firm rather than
a do-it-yourself treatment. Homeowners seldom have the experience,
availability of pesticides and equipment needed to perform the job
effectively. Deal only with a licensed or certified pest control
firm with an established place of business and a good professional
reputation. Ideally the firm will belong to a city, state or national
pest control association. Get at least three competitive estimates
before signing a contract for control measures. Prices for inspection,
treatment estimates and conditions of warranties often vary considerably.
There is no need to be rushed into a termite control program. Delaying
a few weeks or months makes little difference since termites feed
slowly. It is more important to take your time to select a reputable
pest control firm.
- Avoid moisture
accumulation near the foundation. Divert water away with properly
functioning downspouts, gutters and splash blocks. Ground near the
foundation needs to be sloped or graded in order for surface water
to drain away from the building.
- Reduce humidity
in crawl spaces by providing proper ventilation.
- Before and
during construction, never bury wood scraps or waste lumber in the
backfill, especially near the building.
- Remove old
tree stumps and roots around and beneath the building. Never stack
or store firewood lumber or other wood products against the foundation
or within the crawl space.
- Prevent trellises,
vines, etc. from touching the house.
foundations should be reinforced to prevent cracking.
- Use concrete
or steel supports, steps, etc. when in contact with soil.
- Borates (disodium
octaborate tetrahydrate) and/or wolmanized pressure-treated wood
(chromated copper arsenate) protect against termites and wood decay
fungi. However, even railroad ties, telephone poles and pressure
treated wood, over time, can be subject to termite attack. Mud tubes
can be built over the surface or entry gained through cut and cracked
- Most importantly,
eliminate any wood contact with the soil. A 46 cm (18 inch) gap
between the soil and wooden portions of the building is ideal. Try
to maintain at least 15-20 cm (six to eight inches) between ground
level and porch steps, lattice work, door or window frames, etc.
Pull or grade soil back away from the foundation. Wood posts and
stairs embedded in concrete can also be paths of entry for termites.
- Wood mulch
can also attract termites, especially when damp and moist. When
mulch is used, avoid contact against the wood siding or frames of
doors and windows. Pea gravel or crushed stone are much less attractive
to termites, ants, pillbugs, millipedes, earwigs, crickets, etc.
To achieve termite control for long periods of time, termiticides
must be applied as a continuous barrier in the soil at rates required
by their labels. The goal of a termite treatment is to place an
uninterrupted chemical barrier within the soil and adjacent to the
foundation. Anything less can permit reinfestation by termites traveling
through untreated gaps. Most pest control firms will not guarantee
"spot-control" treatments, due to the high probability of termites
eventually finding other untreated points of entry into the structure.
A guarantee or annually renewable contract is normally purchased
for at least the first three to five years after the initial treatment.
Guarantees often vary from firm to firm. Treating foundation voids,
under slabs, in hollow openings of concrete blocks in foundation
walls, and drilling would require still more chemical and higher
costs. When evaluating very low pest control operator (PCO) bid
prices, always ask yourself, "How can someone treat my home for
less than the cost of the chemical themselves?" "will the strength
of the application be less than according to label directions?"
and "are corners being cut by using less solution than required
to best kill all the termites?" Effective termite control usually
requires specialized equipment and often 200 or more gallons of
prepared termiticide solution per house, depending on size, basement,
etc. Termite soil treatment is normally a job for the professional
licensed, certified pest control operator.
baits: Wood or laminated texture cellulose favored by termites
can be impregnated with a toxicant and/or insect growth regulator
(IGR). Termite workers feed on the treated substance and carry it
back to the nest, reducing or eliminating the entire colony. Termite
bait stations are oriented towards a more Integrated Pest Management
(IPM) approach. For more specific details, call Sentricon information
(1-800-686-6200) or FMC Corporation (Firstline) (1-800-321-3621).
A fungus, Metarhizium anisopliae, Strain ESCI (Bio-Blast)
acts as a biological termiticide. It is odorless, vaporless, nonstaining
and infected termites can pass the agent (fungus) to other termites
via horizontal transfer. Bio-Blast is labeled for control of existing
termite infestations in structures and their immediate surroundings
and for residual protection of treated wood. Spray effectiveness
is enhanced when applied to many foraging termites. Treated termites
return to the colony, spreading the biological active ingredient
to others. Treatments can be made both indoors and outdoors.
from the Ohio State University Extension, 1999
Photos by R.A. Casagrande, URI Department of Plant Sciences