Wood-Destroying Insect Control in Your Home

Termites

Each year, many households in Maryland become infested by a variety of wood destroying insects, the most notable being termites. If left unchecked they can cause serious structural damage to a home. In fact, in the United States, termites do more damage to homes annually than all reported fires, tornadoes, hurricanes and windstorms combined.

The termite species that is indigenous to Maryland is the Eastern Subterranean Termite (Reticulitermes flavipes). As its name implies, it lives beneath the soil. Termites, like ants and bees, are social insects and live in colonies. The termite colony is comprised of several castes including a queen, soldiers, winged reproductives (swarmers) and workers. The winged reproductives, or swarmers, are the form most commonly seen by homeowners. Ant colonies also release winged reproductives (flying ants). Many times termite infestations go unchecked when a homeowner mistakes termite swarmers for flying ants.

Characteristics

While termite swarmers are a nuisance, they do not cause damage. Their sole function is to find a mate and begin a new colony. The "worker" caste makes up the bulk of the termite colony and is the only individual in the colony that forages for food and is directly responsible for causing damage to wood and cellulose containing materials. They have no eyes or wings and are soft-bodied, whitish in color and approximately 1/4 inch in length.

The soldiers also have no eyes or wings. They do, however, have enlarged jaws called mandibles which they use to defend the termite colony. They are otherwise similar in appearance to the workers of the colony, whitish in color but their head is enlarged and sometimes brown in color.

Termites are different from almost all other insects in that they can convert the cellulose in wood products back into sugar and utilize it as a food source. In nature, termites are beneficial as they help convert dead wood and other materials containing cellulose into humus. Some other types of insects, such as powderpost beetles and old house borers, eat wood but cannot convert the cellulose to sugar. They receive nourishment from the sugars and starch which the tree stored during its growth. Still other insects, such as carpenter ants and carpenter bees, get no food whatever from the wood but simply excavate holes and cavities in the wood to provide protective shelter.

Carpenter ants

There are a number of ant species that infest homes and buildings. However, the carpenter ant is perhaps the only species that damage wood and are encountered in homes. They do not consume the wood but only build their nests within it. Their foods, similar to those of many other house-infesting ants, are found in kitchens, pantries and other areas where food is stored. Carpenter ants are the largest of the house-infesting ants. Workers within the colony range in size from about 3/16 to 5/8 inches in length. Color varies among species, although black seems to be predominant.

Carpenter ants, like termites, tend to prefer wood that is partially decayed by wood rot. However, they will also attack perfectly sound wood as well. They excavate wood members of buildings, especially when a cavity or enclosed space already exists. Often, these cavities are enlarged to the point that structural damage occurs, but more often the movement of foraging ants within a structure becomes a nuisance. Carpenter ants may travel or forage for distances of several hundred feet. They keep the inside of their excavations clean by discarding the litter of large wood particles (frass) out of the most convenient opening. The coarse frass, when discarded, can be an aid in locating the colony for control purposes.

Wood boring beetles

In addition to termites and carpenter ants, there are a number of other wood destroying insects that can attack wood members in structures. The two most notable are the old house borer beetle and the powder post beetle. Both of these beetles are found in Maryland. The Lyctid powder post beetle attacks only the sapwood of hardwoods with large pores, e.g., oak, hickory, ash, walnut, or pecan, and feeds on starch in the wood. Lyctids range from 1/8 to 1/4 inch in length and are reddish-brown to black in color. The presence of small piles of fine powder (frass) under the wood is the most obvious sign of infestation. The exit holes are round and vary from 1/32 to 1/16 inch in diameter. The larvae are tiny "C" shaped grub-like larvae that are found feeding in tunnels in the wood. Powder post beetles can reinfest the same piece of wood until it is reduced to a shell of frass with the consistency of face powder held in by a very thin veneer of surface wood with beetle exit holes.

The old house borers are members of a large beetle family called the long-horned beetles, named because of their long anntenae. The old house borers were imported from Europe in infested lumber. Unlike the powder post beetle, they attack only the sapwood of softwoods such as pine, spruce, fir and hemlock. The adults emerge in early summer, living for approximately 16 days, during which time the females lay approximately 150 to 200 eggs in cracks or crevices in the wood. The larvae that hatch bore into the wood and take up to ten years to complete their life cycle. The larvae cause the damage by feeding on the wood. The rasping and ticking of their feeding activity is often the first sign or indication of infestation that a homeowner may detect. When the adults emerge they create oval shaped holes in the surface of the wood that are approximately 1/4 inch in diameter. The galleries in the wood are filled with fine frass mixed with small pellets.

Carpenter bees

Carpenter bees are other wood destroying insects that can be found in Maryland. They are large bees that look very much like bumble bees. The major difference is that carpenter bees have a bare, shiny black abdomen whereas bumble bees have a hairy abdomen with some yellow markings. Male carpenter bees are agressive but harmless as they have no stinger. However, females can and will sting if they feel threatened.

Carpenter bees cause damage to wood when they bore holes to create a tunnel in which to raise their young. They prefer softwood such as pine, poplar, cedar and redwood for nesting. The holes they bore are quite distinctive in that they are approximately 1/2 inch in diameter and almost perfectly round.

Other wood-inhabiting insects

There are several other species of insects that damage wood. However, these insects only infest dying or freshly cut trees or unseasoned wood. They do not infest wood that has been kiln dried or seasoned . The ambrosia beetles, bark beetles, horntails (wood wasps), and flat-headed borers fall into this group of wood-inhabiting insects. Control measures are not needed to prevent further damage since the wood was infested prior to milling. Evidence of infestations, such as holes or tunnels, resulting from these insects can be seen on the surface of milled lumber.

Ambrosia beetles

These insects attack unseasoned softwood and hardwood logs. They produce small, 1/50 to 1/8 inch, circular holes. The bore holes do not contain frass, but are frequently stained blue, black or brown.

Bark beetles

These insects tunnel at the point where the wood and bark meet and etch the surface of the wood contacting the bark. Beetles left under bark edges on lumber may survive for a year or more as the wood dries. They do not infest wood.

Horntails

These insects generally attack unseasoned softwoods and do not reinfest seasoned wood. They attack both sapwood and heartwood, producing a tunnel which is roughly C-shaped in the tree. Tunnels are tightly packed with coarse frass and are 1/6 to 1/4 inch in diameter. Frequently, tunnels of emerged insects are exposed on the surface of milled lumber.

Frequently asked questions