Termites, to those of us who are new to the Tucson, Arizona area, we’ve been told are something we homeowners either have, or will have. They are just as much a part of the beautiful landscape of the southwestern desert that drew us as are the coyotes who sing to us at night, and the majestic saguaro that stand continuous guard over us. We are also told of the things that frighten us, rattlesnakes, mountain lions, bears in city parks and packs of Javelinas that will chase you if you are out alone after dark.

No-see-ums, however, and termites are generally a no-see-um, are for many of us more frightening than the big things we can hear (and see) coming – and they can cause considerable damage. There’s just something a little creepy about a critter you rarely see, but that you know can eat your house from down around you. There’s a monthly walk of homeowners here, unknown to those who live outside of the state, but famous here. Homeowners and the people they hire to keep their homes bug free spend copious amounts of time wandering around their homes staring at the foundation, checking for what looks like squiggly straws attached to their homes, one of the dreaded signs of termite trails.

What exactly are these creatures that can cause thousands of dollars worth of damage to our well built homes. Creatures which have caused entire businesses to be built around keeping our homes free of them?

There are over 40 species of termites in 10 genera widely distributed in the Sonoran Desert. Termites are small, white, tan, or black insects that can cause severe destruction to wooden structures. Termites belong an ancient insect group that dates back more than 100 million years. This highly successful group of social insects plays an essential ecological role in the decomposition and recycling of a nutritionally poor, highly resistant, but extremely abundant substance: cellulose. Although many people think termites have only negative impacts, in nature they make many positive contributions to the world's ecosystems. Their greatest contribution is the role they play in recycling wood and plant material. Their tunneling efforts also help to ensure that soils are porous, contain nutrients, and are healthy enough to support plant growth. Termites are very important in the Sahara Desert where their activity helps to reclaim soils damaged by drying heat and wind, and the overgrazing by livestock.

Termites become a problem when they consume structural lumber. Each year thousands of housing units in the United States require treatment for the control of termites. Termites may also damage utility poles and other wooden structures. These pests cause serious damage to wooden structures and posts and may also attack stored food, books, and household furniture.

The ecological importance of Sonoran Desert termites can best be understood by considering the following question: What would happen if we didn’t have termites in our desert? Well, because our aridity severely limits the abundance and distribution of wood decaying fungi, without termites, we would soon be neck deep in cellulose in the form of mesquite and palo verde wood, dead grasses, cactus skeletons and dung. Eventually, few living plants would be left to produce food for animals because there would be no space for new plant seedlings to establish themselves and no nutrients to sustain their growth. All of the space would be taken up by dry, un-recycled cellulose litter, and all of the nutrients would be tied up in this material and thus unavailable for plants in the soil. Without plants fixing carbon-producing food, most animals would disappear. So, without termites, the whole desert ecosystem as we know it would simply collapse.

Tucson area termites partition the Sonora Desert’s cellulose into many ecological niches. For example, one drywood termite, Marginitermes hubbardi, feeds primarily on saguaro skeletons, and another very large primitive drywood termite, Pterotermes occidentis, is a specialist on palo verde wood. Gnathamitermes perplexus, the crust-building subterranean desert termite, feeds on grass, fine dry plant parts and the weathered outer surfaces of woody tissues of all kinds. Heterotermes aureus, the lowland subterranean termite, is an important consumer of native woods on the desert floor, and also of pine.

In the Sonoran Desert large, well-established termite colonies of many species produce nymphs in the late spring. When these nymphs shed their external skeletons for the last time, fully-formed functional wings unfold from the wing pads, and the resultant individuals are called alates. Alates are reproductively mature males and females ready and eager to start their own new colonies. They stay in the parent colony until conditions are optimal (usually during or after a rain); then they leave the galleries of the colony, surrounded by soldier termites ready to defend their brothers and sisters against ants and other enemies as they depart. The alates then take flight.

The season and time of termite flights depend on the species, but alates from all colonies of a given species in an area fly simultaneously. Just how far alates actually fly is not known for any species, but it is assumed that the flights of the reproductive-ready serves to assure new colonization some distance from the home colony – which minimizes competition for existing food and water. The simultaneous flights also promote outbreeding by increasing the probability that reproducers from one colony will mate with members of other colonies.

Soon after winged termites alight, they shed their wings by breaking them off at lines of weakness (like perforations in paper) near the point of their attachment to the body. Females may then use a chemical odor called a pheromone to “call” males. Males attracted to this potent chemical concoction may be accepted or rejected by the female. A rejected male is forced to try his luck elsewhere. The fortunate male who is accepted by a female is permitted to follow her on the ground as she runs quickly about looking for the ideal place to start a new colony. During this “tandem running” phase of courtship, the male remains within touching distance of the female until she finds the “perfect” place (in the ground or in dead wood, again depending on the species of termite and the habitat) to begin a new colony. The pair then settles into a monogamous relationship, and cooperative family rearing.

After mating, the queen lays a few eggs that soon hatch into tiny termite larvae. These are fed and nurtured by both the mother and father until they are large enough to begin foraging for wood and other sources of cellulose, at which time the young termites take over the work of feeding the larvae that have hatched from a second set of eggs. When the parents feed their first batch of offspring, the protozoans (microscopic animals made up of a single cell or a group of more or less identical cells and living in water or as parasites, including ciliates, flagellates, rhizopods, and sporozoans) required to produce the enzyme needed for cellulose digestion are transferred from the mother’s and father’s stomachs to the larvae. This protozoan inoculum is all that is required to get a culture going in the offspring so that they too, with the aid of the microbes, can digest their own cellulose.

Termites can accurately be described as “tiny social cockroaches” because they evolved from a common ancestor with wood-dwelling cockroaches, to whom they are very closely related. They first appeared on earth during the age of the dinosaurs, about 100 million years ago. Termites are social in ways not unfamiliar to humans. We live together with others of our kind in complex societies, we divide the many tasks needed to support our communities and we care for our young long after they are born. Termites likewise live in complex societies, have division of labor, and care for their young.

A well-established termite society or colony minimally consists of a king and queen, which are responsible for producing offspring: soldiers, which defend the colony against its enemies; and workers, which collect and process wood or other sources of cellulose and feed the royal couple and the soldiers, which are unable to feed themselves. Workers also care for eggs produced by the queen, and they tend to the young termite larvae that hatch from these eggs. The categories of king, queen, soldiers, and workers in a termite colony are referred to as castes. All of these are wingless; however, after a termite colony reaches a certain size (a few dozen to several thousand individuals, depending on the species), the colony begins to produce nymphs. These nymphs have small pads on their backs that contain developing wings. Regulation of the development of different castes in a termite colony is controlled by chemicals in the colony that are transferred from individual to individual by social feeding called tropholaxis. Exactly how different developmental trajectories are regulated in termite colonies remains an entomological mystery.

Termites are social and can form large nests or colonies, consisting of very different looking individuals (castes). Physically the largest individual is the queen. Her function is to lay eggs, sometimes thousands in a single day. A king is always by her side. Other individuals have large heads with powerful jaws, or a bulblike head that squirts liquid. These individuals are called soldiers. But the largest group of termites in a colony is the workers. They toil long hours tending the queen, building and maintaining the nest, or gathering food. While other species of social insects have male workers, termites are unique among insects in that workers can be male or female. Surprisingly, termites can be long-lived: queens and kings can live for decades while individual workers can survive for several years.

Residents of Tucson should learn to see the signs of termite infestation. The signs of infestation include swarming of winged forms in fall and spring and evidence of tunneling in wood. Darkening or blistering of wooden structural members is another indication of an infestation; wood in damaged areas is typically thin and easily punctured with a knife or screwdriver.

There are more than 2,500 different types of termites in the world. However most of this diversity can be lumped into four distinct groups: dampwood, drywood, subterranean, and mound builders. Mound builders do not occur in North America, but the other three species do. Dampwood termites are very limited in their distribution: most species are found only in California and the Pacific Northwest. Although the Desert Dampwood Termite can be found in small quantities in Nevada, Arizona, New Mexico, and Texas. Drywood termites are common on most continents and can survive in very dry conditions, even in dead wood in deserts. They do not require contact with moisture or soil. Subterranean termites are very numerous in many parts of the world and live and breed in soil, sometimes many feet deep. Lastly, the mound builders are capable of building earthen towers 25 feet or more in height. Mounds may be located either in the soil or in trees, and where they occur in Africa, Australia, Southeast Asia, and parts of South America, they are very noticeable, and quite remarkable.

Termites are sometimes confused with winged forms of ants, which also leave their underground nests in large numbers to establish new colonies, and swarm in a manner similar to that of reproductive stages of various termites. However, ants and termites can be distinguished by checking three features: antennae, wings, and waist.

Drywood termites infest dry, undecayed wood, including structural lumber as well as dead limbs of native trees and shade and orchard trees, untreated or decaying utility poles, posts, and lumber in storage. From these areas, winged reproductives seasonally migrate to nearby buildings and other structures usually on sunny days during fall months.

Drywood termites have a low moisture requirement and can tolerate dry conditions for prolonged periods. They remain entirely above ground and do not connect their nests to the soil. Piles of their fecal pellets, which are distinctive in appearance, may be a clue to their presence. The fecal pellets are elongate (about 3/100 inch long) with rounded ends and have six flattened or roundly depressed surfaces separated by six longitudinal ridges. They vary considerably in color, but appear granular – and salt and pepper like in color and appearance.

Winged adults of western drywood termites (Incisitermes minor) are dark brown with smoky black wings and have a reddish brown head and thorax; wing veins are black. These insects are noticeably larger than subterranean termites.

Subterranean termites require moist environments. To satisfy this need, they usually nest in or near the soil and maintain some connection with the soil through tunnels in wood or through shelter tubes they construct. These shelter tubes are made of soil with bits of wood or even plasterboard (drywall). Much of the damage they cause occurs in foundation and structural support wood. Because of the moisture requirements of subterranean termites, they are often found in wood that has wood rot.

Reproductive winged forms of subterranean termites are dark brown to brownish black, with brownish gray wings. On warm, sunny days following fall or sometimes spring rains, swarms of reproductives may be seen. Soldiers are wingless with white bodies and pale yellow heads. Their long, narrow heads have no eyes. Workers are slightly smaller than reproductives, wingless, and have a shorter head than soldiers; their color is similar to that of soldiers.

Most termite species swarm in late summer or fall, although spring swarms are not uncommon for subterranean and drywood termites. New kings and queens are winged during their early adult life but lose their wings after dispersing from their original colony. An infestation begins when a mated pair finds a suitable nesting site near or in wood and constructs a small chamber, which they enter and seal. Soon afterward, the female begins egg laying, and both the king and queen feed the young on predigested food until they are able to feed themselves. Most species of termites have microscopic, one-celled animals called protozoa within their intestines that are necessary for converting wood (cellulose) into food for the colony.

Once workers and nymphs are produced, the king and queen are fed by the workers and cease feeding on wood. Termites go through incomplete metamorphosis with egg, nymph, and adult stages. Nymphs resemble adults but are smaller and are the most numerous stage in the colony. They also groom and feed one another and other colony members.

Successful termite management requires many special skills, including a working knowledge of building construction. An understanding of termite biology and identification can help a homeowner detect problems and understand methods of control. In most cases it is advisable to hire a professional pest control company to carry out the inspection and control program.

Management techniques vary depending on the species causing an infestation. Multiple colonies of the same species of termite or more than one species of termite can infest a building. Any of these variables will influence your control approach. Subterranean, and less frequently, dampwood termites can have nests at or near ground level, so control methods for these can be similar. However, drywood termites nest above ground, therefore the approach for eliminating them is unique.

Use an integrated program to manage termites. Combine methods such as modifying habitats, excluding termites from the building by physical and chemical means, and using mechanical and chemical methods to destroy existing colonies.

Before beginning a control program, thoroughly inspect the building. Verify that there are termites, identify them, and assess the extent of their infestation and damage. Look for conditions within and around the building that promote termite attack, such as excessive moisture or wood in contact with the soil. Because locating and identifying termite species is not always easy, it may be advisable to have a professional conduct the inspection.

Building design may contribute to termite invasion. Keep all substructural wood at least 12 inches above the soil beneath the building. Identify and correct other structural deficiencies that attract or promote termite infestations. Stucco siding that reaches the ground promotes termite infestations. Keep attic and foundation areas well ventilated and dry. Use screening over attic vents and seal other openings, such as knotholes and cracks, to discourage the entry of winged drywood termites. Although screening of foundation vents or sealing other openings into the substructure helps block the entry of termites, these procedures may interfere with adequate ventilation and increase moisture problems, especially if a very fine mesh is used in the screening. Inspect utility and service boxes attached to the building to see that they are sealed and do not provide shelter or a point of entry for termites. Reduce chances of infestation by removing or protecting any wood in contact with the soil. Inspect porches and other structural or foundation wood for signs of termites. Look for and remove tree stumps, stored lumber, untreated fence posts, and buried scrap wood near the structure that may attract termites. Consult your local city building codes before beginning repairs or modifications.

Recent research has proved the effectiveness of foundation sand barriers for subterranean termite control. Sand with particle sizes in the range of 10 to 16 mesh is used to replace soil around the foundation of a building and sometimes in the crawl space. Subterranean termites are unable to construct their tunnels through the sand and therefore cannot invade wooden structures resting on the foundation. Stainless steel screening may also be available soon as a physical barrier for subterranean termites.

Replacing Lumber in Structures. Structural lumber in buildings is usually Douglas fir, hemlock, or spruce. Of these materials, Douglas fir is moderately resistant to termites, whereas the other two are not (see Table 1).

The most effective method of chemically treating wood is through pressure treatment. Chemicals currently used in pressurized treatments include chromated copper arsenate (CCA), ammoniacal copper zinc arsenate (ACZA), disodium octoborate tetrahydrate (DOT), and wolman salts (sodium fluoride, potassium bichromate, sodium chromate, and dinitrophenol). Wood containing CCA is tinted green and ACZA is brownish. DOT (borate) is clear in appearance on the wood surface when used at labeled amounts. Borates are gaining in popular usage because of their low mammalian toxicity.

Many of the chemicals used in pressurized lumber can also be applied topically to the wood by brushing or spraying it on. Pressure treatment is preferred over topical application because the chemical penetrates the lumber much deeper (1/4 to 1/2 inch) than it does when applied by brush or spray. Some of the more porous lumbers such as the southern yellow pines (loblolly—Pinus taeda; longleaf — P. palustris; and shortleaf—P. echinata) may be completely penetrated by the chemical during the pressurized process. Topical applications are most effective when used as spot treatments on pressure-treated lumber to treat newly exposed wood when the lumber is cut and drilled during construction.

Pressure-treated lumber is toxic to termites and discourages new kings and queens from establishing colonies in it. If susceptible wood is used above the treated wood, however, subterranean termites can build their shelter tubes over chemically treated wood and infest untreated wood above.

Use only "exterior grade" pressure-treated lumber for areas that are exposed to weather; otherwise the chemical in the lumber may leach from the wood. All topical treatments, especially borates, that will be exposed to weather, must also have a sealer coat to prevent leaching into the soil following rain. Because they contain pesticides, disposal of treated lumber requires special handling. For more information on proper disposal of treated lumber, contact your local Household Hazardous Waste Collection site. For the site nearest you, call 1-800-253-2687.

Treating infested lumber in a structure requires drilling and injecting chemicals into the wood to reach the colony. Because of toxicity and complexity of use, most wood preservatives that are applied to wood in a structure are professional-use only.

Treatments for Drywood Termites include whole-structure applications of fumigants or heat and localized or spot treatments of chemicals or treatments that use heat, freezing, microwaves, or electricity. Techniques to prevent infestations of this species include the use of chemicals, pressure-treated wood, barriers, and resistant wood. Subterranean and dampwood termites in structures cannot be adequately controlled by fumigation, heat treatment, freezing, or termite electrocution devices because the reproductives and nymphs are concentrated in nests near or below ground level in structures out of reach of these control methods. The primary methods of controlling these termites are the application of insecticides or baiting programs.

Use of insecticides or baits should be supplemented with the destruction of their access points or nests. To facilitate control of subterranean termites, destroy their shelter tubes whenever possible to interrupt access to wooden substructures and to open colonies to attack from natural enemies such as ants. For dampwood termites, if infestations are small, destroy accessible nests by removing infested wood. Removing excess moisture from wood will also destroy dampwood termite nests.

Insecticides are applied to the soil either in drenches or by injection. Special hazards are involved with applying insecticides to the soil around and under buildings and a licensed professional does these procedures best. Applications in the wrong place can cause insecticide contamination of heating ducts, radiant heat pipes, or plumbing used for water or sewage under the treated building. Soil type, weather, and application techniques influence the mobility of insecticides in the soil; soil-applied insecticides must not leach through the soil profile to contaminate groundwater.

In the past, chlorinated hydrocarbon insecticides (e.g., chlordane) and organophosphates (chlorpyrifos) were extensively used for termite control, but many of these materials have been phased out because of health and environmental concerns. Active ingredients in currently available termiticides can be broadly classified as repellent or nonrepellent. Pyrethroids, such as permethrin and cypermethrin (Dragnet and Demon), are considered to be repellent. This means that the termites are able to detect the insecticide, which basically serves as a barrier, and they are repelled by it without receiving a dose that will kill them. Therefore, when using these materials it is important to make sure there are no gaps or breaches in the barrier. Also, any adjoining structures must be monitored to ensure that the repelled termites don't infest them.

Recently introduced chemicals (imidacloprid and fipronil) are now available that are less toxic to humans and other mammals than the older insecticides, but are highly toxic to insects. Both of these insecticides are also non-repellent to termites and have been shown to be effective in killing termites at low dosage rates under California's climatic conditions, and therefore are effective for parts of Arizona. Generally, the most effective insecticides are only available to licensed structural pest control operators.

Baits for subterranean termites are commercially available. While this method of controlling termites is very appealing because it does not require extensive site preparation such as drilling or trenching and extensive application of insecticide to the soil or structure, research is still ongoing to develop the most effective baits and delivery systems.

Several bait products (e.g., Sentricon with hexaflumuron and FirstLine with sulfluramid) are available for professional use only. There is also an over-the-counter product (Terminate with sulfluramid) available in retail stores. Currently, baits are only available for subterranean termites, not drywood or dampwood termites. Because subterranean termites vary in their foraging and in the times that they will take baits, the placement of bait stations and the time of installation is a crucial component in a successful baiting program. Be sure to read and follow all the label directions for the product you use. Once a termite infestation is controlled, it is essential that the bait stations continue to be monitored monthly. Spring is an especially critical time to detect invasion by new colonies.

Drywood and subterranean termites are the most destructive insect pests of wood, causing more than $1.7 billion in damages and cost of control each year in the U.S. alone. Their presence in structures is seldom noticed until damage is discovered or the termites swarm within the building. Drywood termites are found in the southern tier of states, from North Carolina through the Gulf Coast and into the coastal areas of California. These are the termites that plague those of us who have moved to Tucson, and in fact all parts of Arizona, to escape the vagaries of climate in the rest of the country.

Termites are a major problem for homeowners in Arizona and across the United States. Nearly every home, new or old has the potential for termite infestation. Most new homes have been treated during construction with a termite barrier before the foundation is poured. While this is an effective deterrent for the pests, it is not 100% effective. If a howeowner disturbs the soil, an opening for termites can be created leading to termite infestation. Arizona homebuilders usually provide a five-year warranty against the presence of termites. Older homes may not have had the treatment at construction time, or the treatment may have become ineffective, leaving the home at risk.

The U.S. is home to many species of termites. The most common ones are the subterranean, drywood and Formosan termites. Most termites fall into the subterranean category and are able to tunnel in the soil. This ability allows them to find many separate pieces of wood on which to feed. This mobility also allows them to create much bigger colonies than those of wood-inhabiting species. A subterranean termite colony can have hundreds of thousands to several million members. Subterranean termites are difficult to spot. The best clue for a subterranean termite infestation is the presence of mud tubes on the walls. Soil-inhabiting termites can also be problems for rangeland, tropical forestry and tropical agriculture. "An ongoing detection and prevention program is essential, since a colony can be established and growing for several years before you will see swarms," Murray said. "By that time, there could be thousands of dollars in damage." Drywood termites can be very serious pests of houses and furniture. These termites are a bit easier to spot - they produce fecal pellets. "If you have drywood termites in your house you are likely to see the coarse sand-like pellets long before you discover the termites themselves," Murray said. "Waiting until you see swarms, mud tubes or actual damage to wood is very dangerous and expensive." "Preventing termites is as important as exterminating them," he said. Murray offers these tips for controlling termites: Check for termite clues, even if you live in a stucco or CBS home. These structures are not immune from termites, even though there is no wood near the ground. Termites build mud tunnels that can extend for 50-60 feet. Termites can also enter a home through expansion joints in concrete slabs, or where utilities enter the house.

At-a-glance: Termites are Built for Destruction. Termites cause over $5 billion in damage to U.S. homes each year. One small termite colony of approximately 60,000 termites can eat a linear foot of a common 2" x 4" in just five months. In some regions of the United States, Formosan subterranean termite colonies typically number in the millions, and forage over 100-meter distances. Subterranean termites cause over 90 percent of termite damage in the U.S. Swarming can begin in January in the South, May or June in the North. Colonies can contain from several thousand to several million foragers. Some termites can chew through lead, asphalt, plaster or mortar to find wood. Almost 4 million U.S. homes are infested by termites each year. Termites can be found in every state except for Alaska. Termites on Earth outweigh humans on Earth. Termite queens live for 15 to 25 years, and can lay an egg every 15 seconds.

Good news for those of you who love Alaska, and choose to live there. Don’t worry, you are the lucky ones. Termites do not seem to thrive in your state, in fact, Alaska is the only state in the Union where termites don’t live. You just have to put up with those man-eating mosquitoes of yours, and of course, some snow. In Tucson, we do have mosquitoes, but only at certain times of the year. Termites are just something we who choose to dwell in the Sonora Desert regions must learn to deal with. Small price to pay for the entrancing vistas and enviable weather.

• University of Nebraska page on Termites
• A summary of termite control methods
• University of California advice on Drywood Termites
• Termite Pest Control Information - National Pesticide Information Center
• African Pygmies - Termites gathering
• Catalogue of the termites of the World
• Pictures of termites
• Transitional Species in Insect Evolution
• Did the Termites Cause Laterites?
• Cretaceous Termites and Soil Phosphorus
• Beneficial Uses of Termites
• Texas A&M University Department of Entomology - Center for Urban & Structural Entomology
• Biomimicry used in Eastgate Building, Zimbabwe
• The Soul of the White Ant - Eugène N. Marais
• Urban Entomology Program University of Toronto
• Harvard University fact sheet on Eastern Subterranean Termites
• Isoptera: termites (CSIRO Australia Entomology).
• 'Termite guts can save the planet', says Nobel laureate
• YouTube: Termites - Life's Ultimate Architects
• USA Pest Management Association's fact sheet on termites
• Termite Control Information from a US chemical supply company