Part 3

The increase in building activity that followed World War II brought the destructiveness of powder-post beetles to widespread attention. The more buildings, the more damage.

The old house borer is rapidly spreading over the eastern half of the United States, and is found more and more in lumber used in new construction. It is becoming one of the most serious pests of wood in buildings.

Powder-post beetles damage wood by tunneling and by cutting surface holes.

Tunneling is done by the larvae of all kinds of powder-post beetles, and by adult bostrichids and cossonid weevils. The larvae of anobiid beetles leave elongate pellets of excreted wood in their tunnels. Other larvae leave powderlike borings. Severely damaged wood becomes a crumbly mass of pellets or of borings, and sometimes has a honeycombed appearance.

Since the insects do most of their tunneling in sapwood, structural damage is rare in large timbers.

Surface holes mar the appearance of wood. Those most commonly seen are made by adult beetles when they emerge from the wood. Those made by many of the smaller beetles are about 1/8 inch in diameter. They give wood the appearance of having been hit by buckshot, and are called shotholes. Larger beetles make holes 1/4 to 3/8 inch in diameter.

Emergence holes made by the old house borer are oval. The lengthwise measurement is about 1/4 inch.

The larvae of some species, including the lyctus beetles, make holes to the surface of the wood and expel borings through them. The larvae of the old house borer seldom pierce the surface; they pack their borings behind them.

DETECTION

Aside from observing tunneled wood, there are several ways of detecting powder-post beetle damage.

You may see surface holes, or borings that have been ejected from them. The borings may be in piles near the holes or, where timbers overhead are attacked, they may be on the floor below.

You may see adult beetles crawling on the wood.

In quiet surroundings you may hear a rasping or ticking sound that is made by tunneling larvae. This is the best way to detect larvae of the old house borer. Their ticking is sometimes audible several feet from where they are working. By determining the source of the sound and by probing the wood with a sharp tool, you can locate the tunnels. A further aid is to look for blistered wood.

Sometimes the larvae of cerambycid beetles can be heard working beneath bark on green or partially seasoned wood. They frequently are found in firewood. They resemble the old house borer, but they have different habits and do not infest seasoned wood. When the adults emerge, they seek more green wood to attack. If they cannot escape from the building, they die in a few days.

WHAT TO DO

Consider whether the control problem is one that you can handle yourself or whether it is one that requires the services of a pest-control operator.

If you have a severe infestation, or one that is behind paneled or plastered walls, or in some other hard-to-reach place, it may be that only an experienced pest-control operator with the proper equipment can do a satisfactory job.

If the infestation is light and easy to reach, you may be able to handle the control job yourself. Spraying or brush-coating the wood with an insecticide may suffice.

If wood has been so badly damaged that its structural strength is impaired, it should be replaced. Coordinate the repair work with the control work.

=Spraying or Brushing=

Beetles that make numerous small holes in the surface of wood are controlled by saturating the wood with a deodorized kerosene, such as deobase or ultrasene, which contains either 5 percent DDT, 2 percent chlordane, 0.5 percent dieldrin, or 0.5 percent lindane.

With 1 gallon of any of these materials you can treat at least 100 square feet of wood surface. Use no more of the material in a single application than is needed to wet the surface. Repeat the application until the wood is saturated. Apply with a garden sprayer or a paintbrush.

The treatment is also effective against infestations in furniture and other wood products.

For best results in treating any kind of material, first remove the finish. This is especially desirable when you treat a large area, such as a floor, but it may not be desirable when you treat ornamental products. Where an infestation in a floor is so small that removal of the finish is undesirable, go ahead and treat the floor, but do not walk on it until it has dried. The drying takes several hours.

The old house borer and other beetles that do not make entrance holes in the surface of the wood can also be controlled by surface applications of these chemicals. Larger quantities must be used, however, especially where thicker wood is concerned, such as floor joists, studs, and roof rafters. For such materials, at least 1.5 pints of the insecticide per cubic foot of wood is needed to reach the beetle larvae. This is equivalent to treating the exposed surfaces of 7 linear feet of a 2- by 10-inch floor joist, 12 feet of a 2- by 6-inch roof rafter, 18 feet of 2- by 4-inch studding, or 12 square feet of subflooring. Even with this thorough treatment, it may take from 3 weeks to 3 months before all the larvae are reached and killed.

The homeowner can best apply such a quantity of insecticide by using a sprayer or a pint-size plastic wash bottle of the squeeze type, equipped with a tube that will produce a pinpoint stream. This makes it possible to apply small enough quantities to cover the surface without causing the liquid to run off. Repeated applications at different times are necessary for complete absorption by the wood and effective penetration. A pest-control operator can obtain results quickly by injecting the chemical under pressure through boreholes spaced at short intervals in the infested wood.

=Slow-Diffusion Method=

Where pressure equipment is not available and you want to use the bore-hole or slow-diffusion method on isolated infestations in wood that is readily accessible, you can use the following procedure: