Bark Beetles and Termites Eat, Hibernate in Wood

The epidemic of fallen trees caused by recent windstorms reminded me to remove a birch stump I’d saved for four years. Because it was so pretty, I intended to carve it into a bowl or toothpick.

Instead, I finally moved it to the curb for collection and spotted tell-tale shelter tubes of subterranean termites lining the interior. I had inadvertently set up an invitation for a pest party, and am now stuck cleaning up after the worst guests ever.

Termites

Sad to say, termites are everywhere. Two varieties plague of Southern California: Drywood and subterranean. These social creatures have been inhabiting wood and soil for more than 100 million years. The upside is their tunneling recycles plant materials and creates porous soil. The downside is the great amount in damage annually to structures. Left unchecked, termites will move from timber to your stored food, paper products and furniture, too. The queen and king of each colony can live for up to 10 years, and Queenie lays thousands of eggs each day. Male and female workers live several years, feeding the royal couple, and grooming and feeding each other.

How do you know if you’ve got them? First clue: You live in Southern California. Second clue: Swarming. Winter and spring, especially after rainy days, squadrons of winged invaders are out looking for new colony sites. Drywood termites are dark brown, with black wings and reddish brown head and thorax. They look like a winged ant. Drywood colonies eat through wood, making it papery thin and easily punctured by as little as a glance. Frass pellets at “kick out” holes in wood are indicators of activity.

Fecal material comes in a variety of colors, and has the shape and texture of ground pepper. Trained inspectors can determine if frass is the result of an old or active colony. Subterranean termites are smaller than their drywood cousins and need a moist environment and access to soil. They eat wood at soil level and below, but will travel up stucco siding in search of moist wood.

In existing structures, create a foundation sand barrier to eliminate access points. Find and eliminate feeding mounds. Keep the building well ventilated and dry. Use fine screening over attic vents but not basement vents, which can trap lower moisture. Meanwhile, remove food and habitat, such as stored lumber, scrap wood, untreated fence posts, and use or remove old firewood that has been sitting longer than a year. This year’s firewood should be stored not closer than 20 feet from the house. Management for drywood and subterranean includes accurate inspection, which is often difficult to achieve for mere mortals, because termites are really good at hiding.

Treat yourself to an inspection by a reputable termite treatment company. A thorough inspection takes at least an hour, probably more, and should be free. Discuss chemical options with a licensed pesticide applicator. Newer products such fipronil and chloronicotinyls have lower toxicity levels. Although this may seem costly, hiring a pro for their big guns infinitely more effective and less expensive than replacing structural wood.

Bark Beetles

There are hundreds of species of bark beetles in California, most of which infest trees stressed by drought, disease or injury. Larvae overwinter in outer bark, eating the inner bark. By late spring, egg laying adults are attracted to dead or dying trees. Cedar and cypress beetles, elm beetles, various pine beetles, fruit tree borers all leave various clues to their presence.

Look for staining on trunk, twig dieback about 6” from tip, bleeding or frothy bubble leaking from bark holes. If possible, peel off a section of bark to reveal feeding mines or galleries. Patterns help determine the type of beetle inhabitant. Galleries of all species are filled with frass. Wilting branches in spring instead of new, vigorous growth can be an indication of beetle activity. Little can be done to control beetles, because they are hidden inside the bark. But consistent and informed tree care helps. Systemic insecticide soil drenches don’t show dependable results so should be avoided.

Corrective pruning after injury is imperative. When replacing trees, select resistant species. Manage irrigation to promote deep growing, healthy roots. Avoid injuring bark or roots during construction or maintenance. Tree wounds are an entry point for infection and infestation. Destroy or fine-chip infested limbs. If a plant is heavily infested, the entire specimen should be removed and destroyed. Do not pile infested limbs next to the trunk of a neighboring tree, or the cycle begins again.