Plant-quarantine inspectors at United States ports of entry often intercept the beetles in bamboo products imported from the Far East. Among the beetles intercepted are the bamboo powder-post beetle, a bostrichid, and the bamboo borer, a cerambycid. These beetles and the lyctus beetles may reinfest the material from which they emerge. [Illustration: Pine floor joist damaged by larvae of the old house borer] DAMAGE 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.