Termite Control Methods and Strategies

Transcription

1 Least Toxic Pest Control LEAST-TOXIC TERMITE CONTROL Termite 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 ecologically-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. MONITORING AND IDENTIFICATION Checking your house annually is important in detection and control of termites. Wood which is soft, crumbly and ridden with tunnels 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, furnaces, and wooden forms around drains. Hollow sounding wood, mud tunnels, piles of wings and fecal pellets are also good evidence of termite infestation. Identifying the specific type of termites is important because of the different control measures. The following five varieties of termites are commonly found in the United States: dampwood, drywood, formosan, powderpost, and subterranean-the biology and least-toxic controls for the different varieties of termites are discussed starting on page 4.

2 Professional services are recommended to properly identify and monitor termite damage. If possible, use an applicator independent of the company doing the inspection. Trained beagle dogs are used by some services to detect termites because of their greater sensitivity and accuracy in detecting wood-boring insects. Please note that the dogs are unable to identify between the different termite species. It is also important to distinguish termites from ants. Termites have curved antennae and broad waists whereas ants have elbowed antennae and narrow 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 difference to accurately determine. PREVENTION Utilizing measures that prevent termite attack should be implemented. This includes eliminating moisture sources by repairing any structural damage, fixing leaks, relocating drains and gutters, etc. Any debris near the foundation of the house such as tree stumps, decaying wood piles, etc. must be removed. Firewood 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 contact 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 desiccating dusts-silica aerogel and diatomaceous earth-may be used in and around wood structures as a drying agent and physical 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) 2

3 CONTROLS Biologicals, temperature regulation, electricity, and least-toxic chemical treatments are the primary methods. A biological control available for termites is insect-attacking 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. Repeated applications of nematodes may be necessary and under ideal moist conditions nematodes may survive a maximum of two years. 10% of its members. Furthermore, 100% mortality for eastern subterranean or Formosan termites takes about two weeks, the company reports. Temperature regulation, especially heat treatments, are an effective control measure 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 recommended for this procedure because of the special equipment and methods involved. 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 Primary methods of control include: Biologicals Temperature regulation Electrical Current Least-toxic chemicals A biological termiticide called Bioblast Was developed by the Ecoscience Corporation 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 nontarget 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 lethal temperature for termites. The temperature must be sustained for a certain amount of time dependent on the type of wood. A large tarp is placed over the outside 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 termites or openings dug out by the operator. 3

4 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 drywood termites but training is required to use this device. This method has been used successfully without causing damage to the structure, however electronic equipment must be moved away from the area to be treated. Research is underway to develop 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 aerogel), synthetic pyrethroids or borax products. Silica aerogel and diatomaceous earth are also effective when used in building 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 humans and pets, a professional is recommended to apply desiccating dusts. If you decide to apply the dusts yourself always 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 replacing 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 insecticides 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 conjunction with the previously mentioned measures. The advantages offered by pyrethroids as compared to harsher pesticides are their lower immediate toxicity and lower persistence. Note: Many of the methods described here may not be available in your region. Discuss and consult with your pest control operator the methods mentioned here or contact the Rachel Carson Council for information on sources of distributors. POST-TREATMENT MONITORING An annual monitoring schedule is a fundamental point in termite infestation and treatment to prevent further problems. After treatment always monitor effectiveness when using the described control measures against termites to determine if more applications or strategies are required. TERMITE SPECIES Termite species specific behavior and control strategies are listed here for the five primary 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 decaying wood caused by a water leak due to the fact that they must have moisture to survive. The fundamental considerations 4

5 here are to kill the termites with desiccating dusts (if necessary due to severe infestation), replace the damaged wood, and repair the leak causing moisture problems. These strategies undertaken individually or in combination should effectively eliminate dampwood termite infestation. Drywood termites are found in the southern and coastal areas of the United States. These termites do not require ample moisture to survive and may invade dry wood through cracks far from the soil. Their nests may be found anywhere in a building structure 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. does not readily decompose and may protect wood for years if applied properly. This dust can kill insects by causing dehydration 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 formulated in combination with pyrethrins, piperonyl butoxide (a synergist) and petroleum (as a carrier). As previously mentioned, always wear a dust mask when applying dusts or hire a professional. Diatomaceous earth* is another desiccating dust that may be used against drywood termites. 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 distributors around the country. Temperature regulation-heat and cold treatments-is a new technology used against drywood and powderpost termites. Heat treatment called Thermal Pest Eradication-is available from pest control operators around the country. In experimental field trials, it has proven to be an effective control measure for drywood termites. Liquid nitrogen cold treatments are another method used to freeze and kill drywood termites and their nests. The liquid nitrogen method offers an advantage in that it allows application to areas not accessible by conventional spot-treatments (Electrogun, dusts, etc.). Silica aerogel, a desiccating dust, is used for effective control of drywood termites. It 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 extensive 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 5

6 attacks one piece of wood at a time whereas the subterranean may attack several pieces at the same time. A preventative method against these termites 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 particles) barriers in the foundations of buildings may also be used as a deterrent for termite attack. Another indirect method is the use of borate barriers (sodium borate) 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 boratetreated wood to replace damaged wood. Please see the section on subterranean termites for details on implementing these control measures. Powderpost termites are found in southern 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. Temperature regulation-heat treatment-is a new technology used against powderpost termites. This method called Thermal Pest Eradication-is available from pest control operators around the country. (see section on drywood termites) Subterranean termites are widely distributed 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 because of their location. These termites must remain in constant contact with moisture thus the infested wood is always 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 throughout 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 termites are sand barriers placed inside or 6

7 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. Another preventative method is the use of borate barriers (sodium borate) around the foundations of buildings to protect wood from termites. Keep in mind that this product is water soluble and is ineffective in areas with high water levels. Least-toxic chemical methods against subterranean 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-diatomaceous 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 effective against termites and other insects. The main advantages to the dusts are nonvolatility, low toxicity to non-target organisms, and long lasting protection. Again, the dusts do pose a potential respiratory hazard to humans and pets so always protect yourself with a dust mask or hire a professional 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 hazard. Always read the label completely for any product to be used. Please contact the RCC if you have any questions) 7

8 SOURCES OF INFORMATION ON PESTICIDES AND ALTERNATIVES Basic Guide to Pesticides. Their Characteristics 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. The IPM Practitioner. Volume XVII, Number 5/6 GREEN RESOURCES Get Some Green Back. Green Mantle Initiative brochure. List of native plant societies, state by state: Gardens Alive!: U.S. EPA Personal Emissions Calculator: Lewis Center for Environmental Studies, Oberlin College: U.S. Green Building Council: U.S. DOE Energy Efficiency & Renewable Energy (EERE): Freecycle organization: RACHEL CARSON COUNCIL, INC Irvington Avenue Bethesda, MD Phone: Rachel Carson Council, Inc., Februay 2014