This Golden Buprestid beetle lived 29 years as a soft white larva inside a hand-made kitchen cutting board. This winter, it chewed its way out as an adult, a flying beetle with iridescent green and copper wingcovers. Photo by Warren Miller.

Sometimes Nature comes right inside our homes. My friend Sandy was surprised when a 3/4 inch-long beetle bored its way out of her kitchen cutting-board! She’d used that board for 10 years, slicing tomatoes, crushing nuts with a wooden mallet, whacking up winter squash. It was a birthday gift from a friend who had made it out of a Ponderosa pine board he’d milled himself, back in 1978. So this beetle’s larval stage had lived inside her cutting board for 29 years before it unexpectedly emerged this February as a startlingly beautiful copper and emerald adult Golden Buprestid or Metallic wood-borer.

Sandy tells this story: “The other day I noticed a small hole in the surface. The next morning something was pulsating in it! We each checked it out with a hand lens. I thought it looked like several somethings. So, we watched a while—that was somewhat ‘boring,’ so I put a glass dish over the area and we left it. Came back later to see part of a beetle emerging! (I had seen its feet and thought that was the other somethings.) By noon, the entire beetle was out—a beautiful golden wood beetle. We have it in a container. Boy were we excited! Turns out, such beetles eat only on dead wood. And sometimes they have come out of big timber beams in buildings 50 years later!”

Sandy’s Metallic wood-borer is a common forest insect in the Northwest. Naturalist Daniel Mathews says it’s “widespread but shy,” a beauty that “rivals our most glamorous butterflies,” in his book Cascade-Olympic Natural History. In the wild, adult Buprestids fly around in forests during spring and summer, eat Douglas-fir needles, mature, and mate. Females lay clusters of pearly oval eggs in bark crevices, usually on a recently fallen Douglas-fir or Ponderosa pine.

The eggs hatch into creamy-white legless larvae (or “grubs,” for the non-appreciators out there). They are worm-shaped except for flat, wide thoraxes, hence their AKA “Flat-headed wood-borers.” The flattened area is armored with hardened plates that protect the soft larva as it hungrily chews its way deep into the dead tree’s heartwood, growing to about 1 1/2 inches long. When mature, it chews its way back toward the surface of the tree trunk where it pupates, transforms into the brightly colored winged beetle, chews a small oval hole, and emerges.

In its natural home, inside a recently dead tree, the larva matures in a few years. But when its wood-home is transformed into a rafter, a picture frame, a bookshelf—or a cutting board—everything changes. Now the larva’s food supply is drastically drier and less nutritious. But the larva doesn’t die, it just matures more slowly. Very, very slowly, even 50 years, as Sandy reports.

People concerned with the dollar value of wood wish there were no such thing as wood-eating insects. Look at the Orpheum Theater in Vancouver, B.C.! Beetles bored through the roof, causing it to leak. Most of the stories I found, though, are about Golden Buprestids occasionally boring small oval escape holes in furniture or wood trim. These are not the beetles that cause widespread “damage” in forests. But commercial foresters describe wood-eaters with words like pest, infest, attack.

People who study ecosystems discuss forest beetles with words like role, cycle, nutrient. When a tree dies, it leaves room for others to grow; as it decomposes, it creates food for new trees. Borers help decomposition by providing entrance holes deep into heartwood for bacteria and fungi. In northwestern forests, Metallic wood-borers are food for woodpeckers and Vaux’s swifts.

Whichever way we “see” wood-boring beetles, they are eye-catching. Postage stamps from around the world feature Buprestid jewel beetles. Another beetle beauty, the scarab, inspires dichroic glass jewelry made by Mike and Nancy McCoy of Essential Glassworks. They write that, to ancient Egyptians, “Scarabs are considered holy, representing the sun due to their circular shape and bright colors. As they burrow deep into the earth, they re-emerge, resurrected and reborn. Hence they are viewed as escorts from death to life, bringers of luck, and protectors of health.”

Maybe Sandy’s beetle will bring good luck!

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