LEAST-TOXIC
TERMITE CONTROL
T
ermite colonies are well-organized communities made up of one or
more queens and a large army of sterile soldier and worker termites.
There are different types of termites based on biology and behavior.
Some termites are ground dwelling and like moist wood. Certain termite
species build tunnels to travel from soil to wood and form small to large oval
fecal pellets. Other species prefer dry wood, soft metal and cracked concrete.
Using an integrated pest management approach (IPM) of control through
prevention, monitoring, management and basic understanding is the
ecolog-ically-sane way of termite control. Some of these methods involve eliminating
all conditions that attract termites, repairing structural damage, non-chemical
techniques, spot-treatments with least-toxic materials, and monitoring for
effectiveness of controls.
Least Toxic
PestControl
MONITORING AND
IDENTIFICATION
Checking your house annually is important in detection and control of termites. Wood which is soft, crumbly and ridden with tun-nels is a good indicator of termite damage. Check possible termite sites such as areas around leaky pipes or faucets, cracks in concrete, vegetation near air vents, fur-naces, and wooden forms around drains. Hollow sounding wood, mud tunnels, piles of wings and fecal pellets are also good ev-idence of termite infestation. Identifying the specific type of termites is important be-cause of the different control measures.
commonly found in the United States: dampwood, drywood, formosan, powder-post, and subterranean-the biology and least-toxic controls for the different vari-eties of termites are discussed starting on
Professional services are recommended to properly identify and monitor termite dam-age. If possible, use an applicator inde-pendent of the company doing the inspection. Trained beagle dogs are
used by some services to de-tect termites because of their greater sensitivity and accuracy in detect-ing wood-boring in-sects. Please note that the dogs are un-able to identify be-tween the different termite species. It is also important to dis-tinguish termites from ants. Termites have
curved antennae and
broad waists whereas ants have elbowed antennae and nar-row waists. In winged forms, a termite’s front wing and hind wing are the same size whereas in ants the front wing is larger than the hind wing. Since the strategies may be different, this is an important dif-ference to accurately determine.
PREVENTION
Utilizing measures that prevent termite at-tack should be implemented. This includes eliminating moisture sources by re-pairing any structural damage, fixing leaks, relocating drains and gutters, etc. Any de-bris near the foundation of the house such as tree stumps, decaying wood piles, etc. must be removed.
Fire-wood or lumber
should always be stored above ground on concrete blocks.
Cracks around the
house should be sealed, especially to protect against drywood termites. Wood in con-tact with soil may be replaced with concrete to prevent attack from termites. When used in building structures, wood should be at least 8 inches above the ground to prevent insect attack. The desic-cating dusts-silica aerogel and diatoma-ceous earth-may be used in and around wood structures as a drying agent and phys-ical control for termites. If sealed off and kept dry, the dusts offer protection for the life of the building.Any dust application should not be inhaled. Hire a professional or use proper safety equipment such as a dust mask.(Note: Do not use the diatomaceous earth used in swimming pool jilters, it has been “calcined” and may be a respiratory hazard. Always read the label completely for any product to be used. Please contact the RCC if you have any questions). Metal
and sand barriers placed in and around a building’s foundation may be used to prevent termite attack. (see section on formosan and subterranean termites for details on barriers)
CONTROLS
Biologicals, temperature regulation, elec-tricity, and least-toxic chemical treatments are the primary methods. A biological con-trol available for termites is insect-attack-ing nematodes. This specific variety of nematodes (microscopic worms) attack only insects and are applied to wood or soil in a water solution. They have exhibited limited effectiveness in tests because of limited range and low survival rate. Re-peated applications of nematodes may be necessary and under ideal moist condi-tions nematodes may survive a maximum of two years.
A biological termiticide called Bioblast™ Was developed by the Ecoscience
Corpo-ration and registered by the U.S. EPA in late 1994 for control of termite infestations. The fungus, Metarhizium anisopliae, is the primary active ingredient in the formulation which is applied as liquid into areas of high infestation. The fungus is not toxic to non-target organisms and is unable to survive temperatures greater than 95°F. Humans should avoid inhalation of the fungus with the proper equipment during application to prevent possible allergic reactions. The fungal spores are transmitted among the termite colony in the feeding and grooming process. According to EcoScience Corp., Bio-Blast™ can reach full effectiveness in as little as four to six days, and a termite colony can be eliminated by spraying just
10% of its members. Furthermore, 100% mortality for eastern subterranean or For-mosan termites takes about two weeks, the company reports.
Temperature regulation, especially heat treatments, are an effective control meas-ure used against drywood and powderpost termites as well as cockroaches, ants, and wood-boring beetles. The temperature in the target area of a building must be raised to 120°F or more. Professionals are rec-ommended for this procedure because of the special equipment and methods in-volved. Hot air is blown in by a heating unit through ducts to raise the air inside the structure to 160°F and the outside wood structures to 150°F. This method raises the temperature inside the wood to 120°F, the
lethal temperature for termites. The tem-perature must be sustained for a certain amount of time dependent on the type of wood. A large tarp is placed over the out-side of the treated area to keep the heat from escaping. This method has been used successfully without causing damage to the structure but some heat susceptible materials (oil products, wax, pianos. etc.) may have to be removed from the area being treated.
Electric current is injected into wood to kill drywood termites with a device called the Electrogun™. This device shoots current into wood through holes made by the ter-mites or openings dug out by the operator.
Primary methods of control include:
Biologicals • Temperature regulation
Electrical Current • Least-toxic chemicals
It uses high voltage and frequency to kill termites within their tunnels and poses no risk to the operator. This tool is available through distributors for use against dry-wood termites but training is required to use this device. This method has been used successfully without causing damage to the structure, however electronic equip-ment must be moved away from the area to be treated. Research is underway to de-velop the use of the Electrogun™ against ground dwelling insects like subterranean termites, fire ants, etc.
Least-toxic chemical treatments against termites include using the desiccating dusts (diatomaceous earth*, silica aero-gel), synthetic pyrethroids or borax prod-ucts. Silica aerogel and diatomaceous earth are also effective when used in build-ing foundations as preventatives against drywood termite attack. Note that silica aerogel is sometimes formulated with pyrethrins; pyrethrins are not nearly as long-acting thus a silica aerogel compound alone may be used as an equally effective preventative and control measure.Due to the potential respiratory hazard to hu-mans and pets, a professional is rec-ommended to apply desiccating dusts.
If you decide to apply the dusts yourself al-ways wear a respirator or dust mask. Borax based products may be applied to the foundations of buildings as barriers to prevent termite attack. Borate-treated wood may be used in building and replac-ing wood structures damaged by moisture or insects. This wood must be above ground and kept dry to retain effectiveness and prevent borate from leaching into soil. Synthetic pyrethroids, such as fenvalerate and permethrin, (not to be confused with natural pyrethrum products) are insecti-cides that are available for use in soil to
form termite barriers. Be aware that these are chemicals that may be moderately toxic if not used properly. These chemicals should only be used as a last resort method in an IPM approach and in con-junction with the previously mentioned measures. The advantages offered by pyrethroids as compared to harsher pesti-cides are their lower immediate toxicity and lower persistence.
Note: Many of the methods described here may not be available in your region. Dis-cuss and consult with your pest control op-erator the methods mentioned here or contact the Rachel Carson Council for in-formation on sources of distributors.
POST-TREATMENT
MONITORING
An annual monitoring schedule is a funda-mental point in termite infestation and treatment to prevent further problems. After treatment always monitor effectiveness when using the described control meas-ures against termites to determine if more applications or strategies are required.
TERMITE SPECIES
Termite species specific behavior and con-trol strategies are listed here for the five pri-mary groups found in the United States: Dampwood termites are found primarily in the western United States down to southern California. Dampwood termites are the largest termite found in the U.S. (1 inch winged forms) and colonies consist of reproductives and soldier termites. This species is almost always found in moist de-caying wood caused by a water leak due to the fact that they must have moisture to survive. The fundamental considerations
here are to kill the termites with desiccating dusts (if necessary due to severe infesta-tion), replace the damaged wood, and re-pair the leak causing moisture problems. These strategies undertaken individually or in combination should effectively eliminate dampwood termite infestation.
Drywood termites are found in the south-ern and coastal areas of the United States. These termites do not require ample mois-ture to survive and may invade dry wood through cracks far from the soil. Their nests may be found anywhere in a building struc-ture and also note that this species spends its entire life in wood. Good indicators of the presence of drywood termites are piles of oval fecal pellets and sawdust pellets near infested wood.
A previously mentioned method for control of drywood termites is the Electrogun™. This method is effective in killing drywood termites but the time required for termite death can range from immediate to several weeks. The device must be used by a trained operator and is available from dis-tributors around the country.
Temperature regulation-heat and cold treat-ments-is a new technology used against drywood and powderpost termites. Heat treatment—called Thermal Pest Eradica-tion-is available from pest control operators around the country. In experimental field tri-als, it has proven to be an effective control measure for drywood termites. Liquid nitro-gen cold treatments are another method used to freeze and kill drywood termites and their nests. The liquid nitrogen method of-fers an advantage in that it allows applica-tion to areas not accessible by convenapplica-tional spot-treatments (Electrogun, dusts, etc.). Silica aerogel, a desiccating dust, is used for effective control of drywood termites. It
does not readily decompose and may pro-tect wood for years if applied properly. This dust can kill insects by causing dehydra-tion upon contact. Note that silica aerogel must be kept dry to retain effectiveness over long periods of time. Also be aware of the formulation you decide to use since some silica aerogel products are formu-lated in combination with pyrethrins, piper-onyl butoxide (a synergist) and petroleum (as a carrier). As previously mentioned, al-ways wear a dust mask when applying dusts or hire a professional. Diatomaceous earth* is another desiccating dust that may be used against drywood termites.
Formosan subterranean termites are commonly found in China and Japan but have spread to some sub-tropical areas in the United States. This species forms ex-tensive mud tubes and possesses a greater potential for damage due to their wide variety of habitats (structural wood, plants, trees, soft metal, cracked concrete). Formosan termites are aggressive feeders which form large colonies in or above ground. Identifying formosan subterranean termites from subterranean termites is an important factor in implementing control strategy. A behavioral difference among the two species is that the formosan variety
attacks one piece of wood at a time whereas the subterranean may attack sev-eral pieces at the same time.
A preventative method against these ter-mites is the use of sand or gravel barriers placed inside or outside foundation walls. These barriers have proven effective in preventing termite attack. The particles of sand must be a particular size (between 10 to 16 mesh sand) to prevent tunneling of termites to wood. A four to eight inch layer of sand inside, outside or both has proven an effective means of protection against termites. Gravel (.07 to .09 inch par-ticles) barriers in the foundations of buildings may also be used as a deterrent for termite at-tack. Another indirect method is the use of rate barriers (sodium
bo-rate) around the
foundations of buildings to protect wood from termites. Keep in mind that this borate product is water soluble and is ineffective in areas with high water levels.
Many of the least-toxic control techniques for the control of formosan termites are similar to those for subterranean termites. These include applying desiccating dusts, breaking open mud tubes, destroying nests, repairing structural conditions which are attracting termites, and using borate-treated wood to replace damaged wood. Please see the section on subterranean termites for details on implementing these control measures.
Powderpost termites are found in south-ern and sub-tropical areas of the United States. They may be found in dry wood, furniture, and floors. They form small fecal pellets and the colonies consist of small
soldiers and winged reproductives. Tem-perature regulation-heat treatment-is a new technology used against powderpost termites. This method—called Thermal Pest Eradication-is available from pest con-trol operators around the country. (see
sec-tion on drywood termites)
Subterranean termites are widely distrib-uted throughout the United States. This species, along with the formosan, are the only groups to build mud tubes which they use to travel from the ground to wood. The tubes protect the termites from predation and drying out. Detecting mud tubes may sometimes be difficult be-cause of their location. These termites must remain in con-stant contact with moisture thus the infested wood is al-ways near to the soil or other constant moisture source. The colonies consist of workers, soldiers, and winged reproductives. They do not form fecal pellets like some other varieties of termites. The mud tubes of these termites can be broken open with a suitable instrument exposing the termites to attack by enemies such as ants and also cutting off access to soil. Termite-attacking nematodes-microscopic worms applied to wood or soil in a water solution-are used by pest control operators to control subterranean termites. These beneficial organisms enter the termite’s body, kill them and spread rapidly through-out a colony due to the cannibalistic and food sharing nature of termites. The use of nematodes has proven to be an ineffective control technique for subterranean termites and more experimentation is required. A prevention strategy against these ter-mites are sand barriers placed inside or
outside foundation walls. These barriers have proven effective in preventing termite attack. The particles of sand must be a par-ticular size (between 10 to 16 mesh sand) to prevent tunneling of termites to wood. A four to eight inch layer of sand inside, out-side or both has proven an effective means of protection against termites. Another pre-ventative method is the use of borate bar-riers (sodium borate) around the foundations of buildings to protect wood from termites. Keep in mind that this prod-uct is water soluble and is ineffective in areas with high water levels.
Least-toxic chemical methods against sub-terranean termites involve the use of borax based products or desiccating dusts. Borax products may be applied as a spray to mud tubes which have been broken open to prevent the termites from reconstructing
the tubes. The desiccating dusts-diatoma-ceous earth· and silica aerogel-kill insects by dehydration through absorption of their body’s outer waxy coating which retains water. If used for spot-treatments the dusts must themselves be kept dry to be fully ef-fective against termites and other insects. The main advantages to the dusts are non-volatility, low toxicity to non-target organ-isms, and long lasting protection. Again, the dusts do pose a potential respiratory hazard to humans and pets so always tect yourself with a dust mask or hire a pro-fessional to apply these products.
(Note: Do not use the diatomaceous earth used in swimming pool filters, it has been “calcined” and may be a respiratory haz-ard. Always read the label completely for any product to be used. Please contact the RCC if you have any questions)
RACHEL CARSON COUNCIL, INC. 8600 Irvington Avenue Bethesda, MD 20817 Phone: 301-214-2400 E-mail: [email protected] www.rachelcarsoncouncil.org
GREEN RESOURCES
Get Some Green Back. Green Mantle™ Initiative brochure.
www.rachelcarsoncouncil.org/index.php?page=get-some-green-back
List of native plant societies, state by state:
www.newfs.org/publications-and-media/resources/nps.html
Gardens Alive!:
www.gardensalive.com
U.S. EPA Personal Emissions Calculator:
www.epa.gov/climatechange/emissions/ind_calculator.html
Lewis Center for Environmental Studies, Oberlin College:
www.oberlin.edu/ajlc/ajlcHome.html
U.S. Green Building Council:
www.usgbc.org
U.S. DOE Energy Efficiency & Renewable Energy (EERE):
www.eere.energy.gov
Freecycle organization:
www.freecycle.org
SOURCES OF INFORMATION ON PESTICIDES AND ALTERNATIVES
Basic Guide to Pesticides. Their Characteris-tics and Hazards. Shirley A. Briggs and Rachel
Carson Council. Taylor & Francis. Washington.
Common-Sense Pest Control. Least-toxic solutions for your home, garden, pets and community. William Olkowski, Sheila Daar,
Helga Olkowski. Taunton Press.
Least-Toxic Management for Termites.
The BioIntegral Resource Center. Berkeley, CA.
New Technologies for Termite Control.
