Drywood Termite Swarmers
Drywood termites are social insects that live in colonies in sound, dry wood. Each colony consists of offspring from an original pair (male and female). There are three growth stages: eggs, immatures and adults. Drywood termites are larger than local, southwestern subterranean species.
In comparison to other termites drywood colonies are rather small (a few thousand individuals), and the colony develops relatively slowly. They neither live in the ground nor maintain contact with the soil and they do not build mud tubes.
Subterranean termites produce liquid feces, whereas drywood termites produce characteristic pellets. These pellets are eliminated from the galleries through kick holes. Pellets tend to accumulate on surfaces located below the kick holes and are usually the first evidence of a drywood termite infestation.
Drywood termites tend to cut across wood grain destroying both the soft spring wood and the harder summer growth. Subterranean termites typically follow the grain of the wood, feeding primarily on the soft spring wood.
The reproductives are winged (alates or swarmers) or wingless males and females that produce offspring. The primary reproductives, also called swarmers or alates, vary in body color from dark brown to light yellowish tan. Their wings may be almost clear to smoke gray, and have few distinct veins in them. Swarmer drywood termites are about 7/16 inch long, including the wings. If the primary reproductives die, they are replaced by immatures that can become capable of reproductive activity. They are known as replacement or secondary reproductives.
In most drywood species there is no true worker caste (subterranean termites do have a true worker cast); this function is taken over by immatures. These immatures are wingless, white to beige in color, 1/4 to 3/8 inch long and make up the largest number of individuals within a colony. They gather food, enlarge the nest and feed and care for the queen, younger immature forms and others in the colony.
Soldiers resemble immatures in color and general appearance. However, they have large, brownish to yellowish-brown heads with enlarged, heavily sclerotized mandibles (jaws). Soldiers defend the colony against invaders, primarily ants. Soldiers are about 5/16 inch long.
After a drywood termite colony has matured, male and female alates fly from the colony and travel varying distances. They are extremely weak flyers, but individuals can travel great distances carried by air currents during the summer monsoon season. Any alates that try to return from the outside are usually killed. Often, the soldier castes congregate around colony openings to defend the release of the alates. Winged alates (swarmers) are produced that leave the colony to establish new colonies. Swarming activity (nuptial flights) generally occurs at dusk or during the night and they tend to fly towards areas of greatest light intensity, gathering around lights or illuminated windows. However, the dark western drywood termite (Incisitermes minor) is a daytime swarmer. Swarming of Arizona species occurs in early to late summer with certain species swarming during the winter months of January and February also.
Some termite species are very regular down to the time and day of year that nuptial flights are made. Other species vary widely on the day and time. Certain environmental conditions, such as heat, light (time of day), rainfall and moisture conditions, wind, atmospheric pressure (especially rapid changes in pressure) and the electrical properties of the atmosphere (associated with thunderstorms) trigger the emergence of alates, and each species has a definite set of conditions under which swarming will occur. The number of alates produced will be proportionate to the age and size of the colony, while environmental conditions regulate the number of swarms emerging from the colony. The bulk of a colonies alates will be released in one or two synchronized swarms, then a few at a time are released throughout the rest of the season. Swarming constitutes a dispersal stage, rather than a true mating flight.
Only a small number of the swarmers survive to develop colonies. The majority fall prey to birds, toads, reptiles, insects (primarily ants) and other predators. Many others die from dehydration or injury. When a pair alights, they shed or pull off their wings and immediately attempt to enter wood. Swarmers usually enter wood through cracks, natural checks, overlapping or adjoining pieces, or exposed end grain. A very small nest is developed after the pair has mated. Initially the queen lays relatively few eggs. The male, or king, remains with the female, since periodic mating is required for continued egg development.
Immatures hatch within several weeks and are cared for by the king and queen. After two molts, immatures assume the role of workers and begin to feed and care for the original pair. Eggs are not deposited continuously, and in fact, very few are deposited the first year. In subsequent years, the young queen matures and will lay more eggs. Eventually, the colony stabilizes when the queen reaches maximum egg production. At that point the colony will contain eggs, immatures, soldiers and reproductives. If the queen dies, one or more secondary reproductives take over her duties. The maximum size of a colony depends on factors such as location, food availability and environmental conditions. Most colonies remain small, but multiple colonies in the same piece of wood may contain up to 10,000 individuals. A colony grows through the queen’s increased egg production and the accumulation of long-lived individuals.
Drywood termites derive their nutrition from cellulose in wood. Within the termite’s gut are large numbers of bacteria and single-celled animals called protozoa. The protozoa produce enzymes that digest cellulose causing the break down of wood particles to simpler compounds that termites can absorb as food. The immatures consume wood and share their nourishment with the developing young, soldiers and reproductives.
Moisture is not as important to drywood termites as it is to subterranean termites. Drywood termites require no contact with the soil or with any other source of moisture. They extract water from the wood on which they feed and also produce water internally during the digestive process. They require as little as 2.5 to 3 percent moisture, but prefer wood with 10 percent moisture content. Drywood termites often establish nests in roof materials and wooden wall supports accessed under eaves. However, despite being capable of surviving on low wood moisture they are also found in wood associated with a water source such as a leaky pipe or water heater. Dead wood accumulating around buildings and homes often serves as a source of infestation.
Homeowners most commonly confuse winged ants with termite alates as several species of ants and termites swarm during the same season.
Characteristics of Damaged Wood
Wood, which has a dull or hollow sound when tapped, should be examined closely. Careful probing of wood with a sharp instrument may disclose drywood termite galleries. The interior of infested wood contains chambers connected by galleries or tunnels that cut across the wood grain. The galleries have a smooth, sculptured appearance and contain few if any fecal pellets. Accumulations of pellets sometimes may be found in blind galleries or unused tunnels.
Control measures include reducing the potential for drywood termite infestations, preventing termite entry, removal of infested wood and applying chemicals for remedial treatment.
Thorough inspections are necessary to confirm termite infestations, assess the extent of damage and determine whether remedial control measures are necessary. Pest Control Operators (PCOs) can perform inspections, or someone who understands the basic elements of construction, the environmental requirements for termite survival and the behavior of drywood termites. Reliable insect identification is imperative. Tools and equipment needed for an inspection include a flashlight, pointed screwdriver, a light hammer, ladder and protective clothing (bump cap, coveralls and knee pads).
A clipboard, graph paper and floor plan or sketch help to accurately depict findings and to ensure that no area of the structure has been omitted. The importance of a thorough inspection for drywood termites and their damage cannot be overemphasized, since the various control measures so closely relate to the extent of infestation and the amount of damage. Thorough sounding and probing is necessary to pinpoint the location and extent of infestations. Precautions should be taken to avoid defacing wood surfaces during inspection if at all possible. If an infestation is suspected it is a good idea to conduct an inspection personally as well as request a professional company to do the same.
When inspecting for drywood termites, carefully examine the exterior of the house, particularly the eaves or any wooden siding or exterior trim . Carefully check corners or under the eaves for spider webs that may contain fecal pellets. Check window and doorframes, sills, roof eaves and exposed ends of rafters . Examine and sound porch roofs and supports, stair carriages and trellises. Open any exterior electrical meter or fuse boxes set into walls and examine them for fecal pellets. Sound and probe wooden roof shingles and any projection to the roof such as dormers, cornices or wood trim. The ends of shingles at roof eaves are the most common places for infestation.
Indoors, carefully examine your home in a room-by-room basis, overlooking no area. Examine door and window frames and trim for damage. Closely examine the baseboards on the perimeter walls, particularly if you have wood flooring. Check windowsills for fecal pellets or discarded wings. Check the insides of built-in cabinets by removing drawers and opening doors. Exposed beams and wooden paneling should be examined thoroughly, as well as places that are continually warm such as near water heaters and furnaces. Drywood termite damage seldom can be observed on the wood surface; however, sometimes painted wooden surfaces will look blistered if termites have tunneled close to the surface. A sign of advanced infestation is surface blistering that can be probed with a sharp screwdriver.
Quite often, termite problems encountered by homeowners could have been prevented through sound initial design practices, mechanical alterations or sanitation. The basic premise behind prevention is denying termites access to wood. Preventing drywood termite infestation is more difficult than preventing subterranean species as the outside of homes have many sites where termites may enter. However, certain preventative measures can be effective. Remove all potential sources of outdoor infestation such as stored lumber, firewood, scrap lumber and dead trees or woody shrubbery. Screen attic or foundation vents with bug screen to exclude drywood termite alates. The screening of vents along with good maintenance of window screens will exclude a multitude of unwanted critters from you home. This may not be practical in areas of high humidity, since it restricts air movement needed to keep attics and subfloor areas dry. However, this is rarely a problem for most of Arizona. Drywood termites will not enter wood that has a sound coat of paint. Before painting, seal any cracks, natural checks, construction scars, crevices and joints with wood putty. No effective way has been developed to prevent drywood termites from entering under or through wood shingles. Preconstruction planning offers opportunities for preventing termite infestation. Wooden structural members can be soaked in or painted with borax derived wood preservatives. These materials may not penetrate wood deeply, though, so a touch-up will be necessary before closing in the building. Commercially pressure-treated wood is more desirable and may be used as framing members, subflooring, window and doorframes, trim and possibly even wood siding. The extra cost of pressure-treated wood may be justified where termite problems are common.
There are several alternatives for dealing with drywood termite infestations or damage, depending on the extent of the problem. This places great importance on an extremely accurate inspection of the structure.
No Control: Where the infestation is slight or damage is cosmetic and limited to one or two small areas, you may choose not to use any control measures. Drywood termite colonies often develop slowly; therefore, the costs incurred with some control measures may not be warranted. But if you choose not to control, be sure to maintain a monitoring program so you’ll know when and if control becomes necessary.
Wood Replacement: Where the infestation is limited, remove and replace damaged wood, preferably with pressure-treated wood that will protect against both termites and wood decay. Or it may be more practical to have a pest control operator apply special formulations of wood preservatives. They penetrate fairly deeply into unpainted wood surfaces, particularly cut ends and structural joints. Certain precautions are necessary to protect ceilings and painted surfaces from staining.
Fumigation: If infestations are widespread or suspected in areas that cannot be inspected or replaced (such as in wood shingles, between walls or in eaves or attics), fumigation is a control alternative. First, a structure is completely enveloped in gas-proof tarpaulins or heavy plastic sheeting. Masonry construction with flat, composition shingle roofs may be sealed around the doors, windows and vents. Then a fumigant gas is released into the structure. The gas penetrates into cracks, crevices, void areas and directly into wood to kill termite colonies. Lethal concentrations are contained by the tarpaulins long enough to permit uniform penetration deep into all infested areas. Despite its effectiveness, there are disadvantages to fumigation. It does not leave any chemical residue to deter future infestation. Fumigation is extremely hazardous and the occupants of the home may have to vacate for several days. Also, fumigation is labor intensive and requires the specialized knowledge of a licensed, professional pest control firm and can be expensive. Fumigation requires special certification because of the extreme hazard. It is imperative to remove all household pets, plants and food products from the home prior to treatment.
Subterranean termites are the single greatest economic pest in the United States. These termites cause billions of dollars in damage each year to homes, historical structures and commercial buildings. In addition to buildings, termites also consume valuable books, documents and photographs. Subterranean termites have existed for over 55 million years and are extremely good at what they do. A great deal of their success can be attributed to their cooperative behavior. Subterranean termites are social insects. This means that they live in family groups called colonies. Social insects are different from other insects (grasshoppers, cockroaches, or beetles) because each termite in the colony performs a specific job that benefits the colony as a whole. Most other insects work only for themselves. For example, each individual grasshopper will feed and reproduce itself independently of its siblings. In the termite colony an entire group or caste of termites is responsible for feeding their parents and siblings, while another caste is responsible for reproduction. Because of this division of labor, the colony of individuals functions as a single animal. The following is a description of how a subterranean termite colony becomes established and how the different castes interact and communicate as the colony grows.
During the daylight hours of the spring months, homeowners may begin to see winged termites emerge in large numbers inside their home or from the soil outside. These are the subterranean termite swarmers. The swarmers are new termite kings and queens that must leave their parent colony in order to mate and establish new colonies of their own.
The termite swarmers pair up during their flight then land and search for a place to begin a family. Their wings break off shortly after landing and the new king and queen start their colony by excavating a small chamber in a crevice or plot of soft soil. When the chamber is large enough, they crawl inside, seal the opening and mate. From this point on, they will spend the rest of their lives underground. The queen lays her first batch of (6-12) eggs within a few days or weeks of mating. Initially, the king and queen tend the young termites. However, as the queen’s egg laying capacity increases, the older offspring begin to tend their younger siblings. The colony will now continue to grow with increasing numbers of termites being produced each year. The parental king and queen have the longest life span in the colony. They often survive for a decade or longer and can produce huge colonies with thousands of offspring.
If you are certain that subterranean termites have infested your home, the time to treat is NOW. There is no best time to treat for them. Summer, winter, spring or fall, subterranean termites can be active all year round in a heated building.
Subterranean termites will not just disappear or go away. If they have infested your home or business, the only thing that will stop them is a proper treatment. If you do nothing, the termites will continue to eat and cause damage. At some point, structural damages could occur. If you are battling formosan subterranean termites, (Gulf Coast areas), your entire home could be destroyed in as little as a year and a half.