Termites and Wood-Destroying Insects and the Damage They Cause

 Subterranean Termites

Subterranean termites are social insects that live in nests or colonies in the soil, hence their name “subterranean.” These colonies contain three forms or castes: reproductives, workers and soldiers.   Reproductive males and females can be winged or wingless. The bodies of primary reproductives, also called swarmers, vary by species from coal black to pale yellow-brown. Wings may be pale or smoky gray to brown and have few distinct veins. Swarmer termites are about 1/4 to 3/8 inch long.   Termite workers make up the largest number of individuals within a colony. Workers are wingless, white to creamy white, and 1/4 to 3/8 inch long. They do all of the work of the colony -- feeding the other castes, grooming the queen, excavating the nest and making tunnels. In working, they chew and eat wood, causing the destruction that makes termites economically important. Soldiers resemble workers in color and general appearance, except that soldiers have large, well-developed brownish heads with strong mandibles or jaws. Soldiers defend the colony against invaders, primarily ants.

Subterranean termites invade homes from the soil around and beneath the structure. Infestations occur when subterranean termite workers locate structural wood in contact with soil or when termites build shelter tubes from the soil across foundation walls and into structural wood. Subterranean termites may also gain access through cracks in the slab or seams where plumbing and electrical lines penetrate the concrete. Foundations made of hollow blocks, or of masonry and rock provide several avenues for termites to gain undetected access to wooden parts of the structure. Once inside, subterranean termite colonies maintain access to the soil around or under a home. The soil provides them with the necessary moisture to remain healthy.  It typically takes several months or years of feeding for termite damage to be significant. Termites prefer to feed on the soft grain of the wood. In severely infested wood, only the hard grain and a thin outer shell remain. Termites intentionally remain hidden within infested wood, preferring not to be exposed to the outside environment. This makes it difficult to locate infested wood in a structure. An infested timber can look perfectly normal on the outside, even when riddled with termite galleries on the inside.

 

Carpenter Ants

Carpenter ants are one of the most common wood-destroying insects found in and around the home. They are attracted to wood which has been exposed to moisture. Carpenter ants tunnel and make nests in soft wood; however, they do not eat the wood. The largest of the ant family, the carpenter ant ranges from 1/4 to 3/4 inches, has a constricted waist, bent antennae and is black, reddish-black or brownish black in color. Winged carpenter ants can be distinguished from termites by their larger size and shape of their antennae, waist and wings.

Any wooden areas (porch, tree, veranda, step, door, etc.) which become moist are vulnerable to carpenter ant attack. This is particularly true of rotting sections of wood. The worker ant finds an entry route by gnawing a clean tunnel parallel to the wood grain wherever a crack or crevice exists. The wood is chewed and discarded outside the tunnel. The discarded shavings, which resemble sawdust, provide an indication of nesting areas. Often, the nest is extended into sound wood.    Besides being objectionable by their presence, carpenter ants damage wood by hollowing it out for nesting. They excavate galleries in wood which have a smooth, sandpapered appearance. Wood which has been damaged by carpenter ants contains no mud-like material, as is the case with termites.

 
Carpenter Bees

Carpenter bees are large - three-fourths to one-inch long - and robust. They are colored black with a metallic sheen. The thorax is covered with bright yellow, orange, or white hairs, and the upper side of the abdomen is black, glossy, and bare. The female has a black head, and the male has white markings on the head. Carpenter bees have a dense brush of hairs on the hind legs and somewhat resemble bumble bees, except bumble bees have dense yellow hairs on the abdomen and large pollen baskets on the hind legs.

Carpenter bees are so named because they excavate galleries in wood to create nest sites. They do not consume wood. Rather, they feed on pollen and nectar. Carpenter bees are important pollinators of flowers and trees. Carpenter bees typically are just nuisance pests that cause cosmetic rather than structural damage to wood. Nonetheless, considerable wood damage can result from many generations of carpenter bees enlarging existing galleries in wood.

Powder Post Beetles

Powder post beetles are so called because in high numbers they are able to turn the inside of a piece of wood into nothing more than a mass of fine powder.  These wood destroying insects can do significant damage to furniture, wood floors and structural timbers.   Powder post beetles are small (1/8 inch) and the adult beetles are seldom seen.  Most of the life cycle is spent in the grub or larvae stage eating wood.

Damage is done by the larvae as they create narrow, meandering tunnels in wood as they feed.  This stage can last between 1-10 years depending upon a number of factors; these include species of beetle, type of wood infested, age of wood, moisture content of wood and air temperature. The exit holes are very small, about the size of a pin head.

 
 

Old House Borers

The old house borer is one of the most injurious wood-destroying insects. The name is somewhat misleading since a large number of infestations are noticed in homes just four to seven years after construction. The larva bores through wood and also feeds on it. Tunnels made by the larva weaken structural timbers. The borers feed only in pine, spruce, and other coniferous woods.

Infestations are hard to detect in the early stages since larvae are small, develop slowly the first year and there are no external signs of damage. Only in advanced stages will surface bulges become evident due to larval activity. Homeowners may hear their gnawing "clicking-like" sounds. By breaking the surface with a sharp object where tunneling is suspected, one can find tiny rod-like fecal pellets (which crumble easily) and fine, powdery material.   The oval exit hole created by the emerging adult old house borer can be 1/4 inch to 3/8 inch in diameter.