Termites

Encyclopedia Article

Termites in Iowa

Termites and carpenter ants are the most damaging wood-destroying insects in Iowa. Termites are more common in the southern half of Iowa but have been reported in almost every county in the state.  Termite infestations in Iowa are spotty and widely scattered. 

Termites are social insects, as are honey bees, ants, and some wasps. Social insects live within a colony of overlapping generations. The colony members cooperate in caring for the young and work to ensure the success of the colony.

Damage

Picture of termite workers by MJ Raup, University of Maryland
Eastern subterranean termite workers.  Photo by MJ Raup, Univ of MD.

In natural ecosystems, termites are beneficial because they feed on decaying logs and stumps, breaking down wood and recycling the nutrients. However, termites are destructive to homes and other buildings because they eat building materials and structures made of wood. Given sufficient time, termites may consume enough wood to weaken the structure or necessitate replacement of structural lumber, flooring, moldings, wallboard, paneling, siding, or landscape timbers. Termites may also damage other cellulose-containing items such as paper, books, cardboard, art canvases, the paper covering of drywall, and insulation.  

The amount of damage that termites cause depends on the type of wood, available moisture, and temperature. Termites work slowly in Iowa's climate and are generally not active during the winter. It may take years of unseen termite activity before there is significant or observable damage. There are no test procedures, measurements, or calculations that determine how long termites have been "working" in a damaged area.

Life cycle

Termites have a simple life cycle of three stages – egg, nymph, and adult. However, the development of termites is more complicated than that because of the different forms (castes) that maintain a division of labor within the termite colony. 

The three termite castes are soldier, worker, and reproductive. Soldier termites are sterile adults that protect the colony against invasion by ants or termites from other colonies.

Workers (1/8-inch long; soft, creamy white body; wingless; bead-like antennae) are the most numerous members in the colony. They excavate chambers, build nests, construct tunnels, forage for food that they carry back to the nest, cultivate fungus gardens, and feed and care for the colony members. Workers remain entirely inside the wood they are eating or in the colony.

Reproductives are sexually developed adult females and males ("queens" and "kings"). A termite colony may have several queens laying eggs while being waited on by the wComparison of winged ants and winged termitesorkers. 

Swarmers (3/8-inch, straight-sided, black body, silvery wings) are male and female adults that emerge from well-established colonies to attempt to establish new colonies.  Only mature colonies (those established and growing for years) produce swarming termites. Several hundred or more swarmers may emerge during mass flights, most often in the spring. Swarmers are the termite stage routinely noticed in residences.

Drywood Termites

Drywood termites are rare in Iowa. They have been found here in furniture transported from the southwestern and southeastern United States. They may also attack the structures where infested furniture is kept. As the name implies, drywood termites establish in dry, sound wood that may have as little as 3 percent moisture content.

A symptom of drywood termite attack is the accumulation of tiny, tan, six-sided, fecal pellets that sift from small holes in the surface of infested wood and accumulate inside or beneath infested furniture. Eradication of drywood termites from furniture too valuable to discard should be done by a pest management professional.

Subterranean Termites

The termites found in Iowa live in underground tunnels and chambers, giving them the name "subterranean” termites. They live in the soil to obtain moisture, but they also nest in wood that is continuously wet and warm.  Subterranean termite workers randomly explore for food by excavating a network of pencil-sized tunnels through the soil. Homes become infested when the termites find a way into the house during their constant search for food.

Hollow termite shelter tube made of mud on foundation wall
Termite mud shelter tube.  Photo by FE Wood, Univ of MD.

Shelter tubes are most apparent when on the surface of foundation walls, floor joists, or other exposed surfaces.  Mud tubes may be concealed in cracks in the foundation, between the foundation and basement floor, in the gaps between boards or large timbers, underneath flooring, or behind siding and baseboards.

Damage inside structural wood, drywall, paneling, and molding may be detected by staining or blistering of the wood, or when the remaining thin outer shell of the wood or drywall is easily crushed.  Exposed galleries tend to follow the wood grain; the soft, lighter-colored springwood of the annual rings will be eaten but not the dark, harder summerwood.  Galleries are usually lined with a light brown, gritty coating of soil particles and moist fecal material similar to the material used to make mud tubes.

Termite Management Options

For information on available treatment options, please see our article, Termite Control in Iowa. 

Presence of termites in or near a house, visible mud tubes, or suspicion of any of the symptoms described are reasons for an inspection of the house and property by a local, experienced, pest management professional.  If termite activity is confirmed or if treatment is recommended, get at least three opinions and treatment estimates.  There is no need to panic or rush. Termites work slowly, and you have time to get complete information.

Eliminating an existing termite infestation is not a do-it-yourself project.  Termite treatment is complex; specialized equipment and skills are needed for thorough and effective protection of your home.

Last Reviewed: 
July, 2020
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