Drywood Termite

Many residents of Florida, especially those living near the coast or in southern counties, will experience a drywood termite infestation in their home. Unlike subterranean termites which require excess moisture, drywood termites spend almost their entire life cycle inside the sound, dry wood members upon which they feed. Only during brief swarming flights do young adults leave the confines of their galleries to begin new colonies elsewhere. Winged adults or “swarmers”, shed wings, ejected pellets, and galleries inside wood are typical signs of a drywood termite infestation. Swarming ants are sometimes confused with termites, but their differences are easy to recognize.


Drywood termites colonies are small, usually under 1000 individuals. The workers are usually whitish, slow moving, and long bodied. In most genera, the soldiers look quite typical of most termite soldiers, but Cryptotermes is different. The soldiers have a small stub head (phragmotic head) and short mandibles, with which they use to block tunnels against intruders.


The king, queen, and nymphs are all mobile and able to move within the nest, which is relatively simple in structure, usually consisting of numerous galleries and chambers within wood. The queens are only slightly physogastric (enlarged abdomen) which allows them to be mobile.


The insides of the galleries and chambers are often filled with their droppings, especially in old nests. Along the wood surface, tiny “kick holes” open to the outside, through which the termites periodically dump their droppings. Once the wood becomes too damaged, the colony gradually migrates to any connected/adjoining wood.


The damage wrought by drywood termites is slow, and it takes years before their presence is noticed. A single colony that nests in a piece of wood will often just inhabit and eat out this single piece of wood, leaving adjoining areas untouched. Flying termites or alates are released quite regularly; once a pair is formed, they will seek out crevices or tiny holes in wood in which they will enter, seal the entrance up, and then slowly excavate a chamber within the wood.

Drywood Termite Control

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.


♦  Localized or Spot Treatments. There are many localized/spot treatment methods available that include both chemical and nonchemical options. The chemical options include liquid organophosphates and pyrethroids, borate and desiccant (silica gel) dusts, and liquid nitrogen. For the liquid and dust insecticides to be effective, they must be touched or ingested by termites.


Efficacy information is lacking for most chemical spot treatments for drywood termites. For all spot treatments of chemicals it is critical that all infestations in a structure are detected so that they all receive treatment.


♦  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.

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