Iowa Insect Information Notes

Termites in Iowa

Termites in Iowa

The termites commonly found in Iowa are called subterranean termites because they live underground. Termite colonies are highly organized societies of several hundred thousand to 1 million or more individuals within a loose collection of underground tunnels and chambers. Workers (1/8-inch, creamy white, wingless, segmented body, bead-like antennae) are the most numerous members of the colony. They build and maintain the nest, care for the immatures, and forage for food to eat and carry back to the nest. Termite food consists of wood and other cellulose products such as paper and cardboard. Reproductives, i.e., queens and kings, produce the new offspring, while soldiers guard the colony from invasion. Swarmers (3/8-inch, straight-sided, black body, silver wings) are male and female adults that emerge from well-established colonies to attempt to establish new colonies. Subterranean termite workers constantly explore for food by excavating a network of random, pencil-sized tunnels through the soil in the area surrounding their nest. Foraging may occur over considerable distances --- up to 100 meters (330 feet) in some cases. Homes become infested when the termites find a way into the house during their constant and random search for food. A termite infestation in the home is usually not obvious because most activity in concealed. Signs of a termite problem include the presence of pencil-wide mud foraging tubes on foundation walls, floor joists, etc., the presence of damage inside structural wood, drywall, paneling, molding, paper or cardboard, and emergence of swarmers. Presence of termites in or near a house is reason for inspection of the house and property. There is no need to panic or rush. Take your time to get complete information. If termite activity is confirmed or if treatment is recommended, get at least three opinions and estimates from local, reputable pest control firms.

Termite Treatment Options

For over 50 years, subterranean termites have been controlled by chemical barriers in the soil, around and beneath a structure. Special insecticides called termiticides are used for this purpose. A complete barrier treatment may require hundreds of gallons of termiticide solution. The water-based solution is injected 3 to 5 feet into the ground alongside the foundation, beneath concrete slabs (basement and garage floors, patios, sidewalks, and driveways), and within foundation walls. A complete and continuous barrier of termiticide will block potential routes of termite entry and continue to protect the structure for years. Termites attempting to penetrate through the treated soil are either killed or repelled. Pest control operators use several different termiticides. All are safe and effective when used carefully according to label directions and will remain effective in the soil for approximately 5 to 10 years. The second termite control option is termite bait. Termite baits, available since approximately 1995, consist of a palatable and acceptable food material combined with a very slow-acting toxicant. Termite baits deliver very small amounts of pesticide over a long period of time (up to several months). Control depends upon foraging termites finding the bait, feeding, and carrying it back for transfer throughout the entire colony during the normal process of food exchange within the colony. Termite baits are dispensed through plastic boxes and tubes (bait stations). In-ground stations are buried just under the soil surface around the structure. Termites find the stations (and bait) during their random search for new food sources. Above ground stations are used indoors where termite feeding activity or tubing is occurring. Such placement speeds the baiting process but is not possible in all situations. Baiting is a slow, long-term solution to the termite problem within a structure. A comprehensive baiting program seeks to maintain a termite-free condition through ongoing monitoring and rebaiting as needed. A combination of barrier and bait treatments may be appropriate in some situations. Any treatment (barrier, baiting system or combination) can be done as prevention before termites begin to feed inside the house or as a cure to stop activity that has already started.

Advantages of Termite Barriers and Baits

Conventional termiticide barrier treatments have controlled termites very well for many decades with very little harm to humans, pets or the environment. However, there are potential risks from such treatments that cause some individuals to prefer an alternative. Termite baits are far less toxic than most liquid termiticides, an advantage to chemically concerned homeowners. Further, the total amount of pesticide applied in baits is minute compared to the hundreds of gallons of termiticide needed to completely treat a house in a thorough and effective manner. Termite baits "target" the pest species with little or no chance of impact on groundwater, wildlife or the environment. The risk of contamination of wells, heat ducts, drainage systems, etc. is negligible and baits can be used in the most sensitive treatment situations. Baits are applied with no destruction or disruption to the house. No holes are drilled through floors or walls and furniture, stored items, and carpeting or flooring will not have to be moved or removed. Buildings with a history of chronic termite retreatment are logical candidates for termite baits as are houses with construction features that make barrier treatment difficult or impossible (wells, in-floor heating ducts, perimeter drainage systems, inaccessible crawl spaces, stone foundations, etc.). Barrier treatments usually provide faster, if not immediate results that may be desirable in some situations. For example, you may not want to wait several months while baits suppress or eliminate the infestation in properties with a severe termite problem, or if there is a real estate transaction in process. Termites may continue to damage the home through the baiting process and delayed results may be unacceptable. While barriers will provide longer control from a single visit or application, the termiticides can be expected to protect for only 5-10 years, after which time retreatment may be necessary. It is understood that control by bait is a long-term commitment to ongoing inspection, monitoring and rebaiting when necessary. The costs for conventional and bait treatment are similar. When comparing prices consider both the initial treatment price and renewal fees.

Success of Termite Bait in Iowa

Termite baits have been used to treat homes in Iowa since 1995 and the results of this new technology are being watched carefully. Most of the initial research with termite baits was done in the southern U.S. where termites are active year-round and soils and building construction practices are different than ours. However, the limited but rapidly-increasing amount of experience with the new bait products by pest control operators in Iowa and other Midwest states has been favorable. Bait systems rely on termites locating (by random chance) the in-ground bait stations placed around the home. In research conducted in the southern states it sometimes took 3-5 months for termites to find the bait stations. In the northern states where termites are only active for about half the year the bait stations may not be found for a year or more. In Iowa, the length of time necessary for termites to find the in-ground stations has varied from as little as 2 days to as long as 2 years. However, termites have entered the bait stations within 1 year at approximately 80% of the houses treated. Bait stations appear to be found more rapidly when installed in the spring rather than in late summer. Success with baiting requires frequent inspection in an ongoing monitoring program and rebaiting as necessary. While it is too early to know under what circumstances termite baits are going to be most effective, many houses have already been successfully treated (that is, termites or new termite activity has not been found during on-going inspections). Research to document whether successful control of termites is the result of colony suppression or colony elimination has not been done.

Baits available from commercial applicators

Trade Name Active Ingredient Manufacturer
Firstline sulfuramid FMC
Labyrinth diflubenzuron Ensystex, Inc.
Sentricon hexaflumuron Dow AgroSciences

Homeowner Application of Termite Bait

Termite baits are a recent alternative for termite control. Baits combine a slow-acting substance lethal to termites with a food material such as paper or cardboard in plastic tubes or boxes installed below ground around the house or indoors near termite activity. After foraging termites find and consume the bait they share it with their nest mates, resulting in gradual decline in termite numbers. Very recently over-the-counter termite bait products became available for direct sale to homeowners (for example, "Spectracide Terminate Bait"). The chance to save substantial amounts of money with a do-it-yourself termite bait treatment further complicates the difficult process of making a termite control decision. Iowa State University Extension does not recommend do-it-yourself termite treatment (termiticide barrier or bait) for whole house termite protection. Limited spot treatments of lower value structures (sheds, fence posts, landscape timbers, etc.) may be practical but attempting an amateur approach to protecting something as valuable as a home is not prudent. While baits may be easy to install, the lack of a detailed understanding of the art and science of termite biology and habits will severely limit the chances of success. Baits alone are not sufficient for controlling termites. A complete program should include a structure or site modification, along with chemical treatment using liquid termicides, or bait or both. Clearly, an experienced, well-trained professional should be the one to coordinate the long-term program. OTC termite bait products provide incomplete, inaccurate or misleading instructions. The most critical limitations are oversimplification of the process and lack of evidence to substantiate claims of an easy and quick solution to the termite problem. Baits will not perform up to homeowner expectations by simply being hammered into the ground and ignored. Amateur application of a limited number of bait stations will likely result in a false sense of security. Termite control success requires thoughtful installation and diligent monitoring by a trained and experienced professional service technician, backed by a responsible pest control firm. Shop around and gather a variety of opinions and learn as much as possible before making decisions about termite control.

Further resources Selecting a Termite Control Service. (PDF)

Updated 07/14/2005 - 3:56pm