The emerald ash borer is a beetle from Asia. Despite its beautiful name and lovely appearance — it has metallic green wing covers and a coppery red or purple abdomen — it is a potent killer of ash trees.

The borer’s kill rate in America is almost 100 percent. Only a tiny percentage of trees manage to survive once infested. Tens of millions of ashes across the U.S. have been lost to the beetle.

Scientists believe the ash borer migrated to this country in wood used for packing crates.

Adult emerald ash borers nibble on ash foliage, but cause little damage. However, from the middle of May to the middle of August, they lay eggs on ash bark.

The eggs hatch and the larvae tunnel into the tree.

From August to October, the larvae feed under the bark, creating S-shaped, zig-zag trails. They feed on the inner bark, disrupting the tree’s ability to transport water and nutrients.

The next spring, new adults emerge from D-shaped exit holes in the dying ash tree and fly off in search of other trees to lay eggs on.

A certain nonstinging ground wasp, cerceris fumipennis, can be used to locate and track the emerald ash borer. This is called biosurveillance. Here’s how it works.

The wasps build their nests underground, come out early in July, enjoy the warm weather for a month or two, then die.

During their two months of above ground activity, the wasps capture and bring back to their nest a variety of insects, including emerald ash borers if they can find any, to feed their larvae. Next July, the larvae emerge as adults to live above ground for a couple of months.

Though cerceris feeds on the ash borer, it can’t eat enough of them to slow the spread. Nonetheless, if there are ash borers around, cerceris will find them and bring some back to the nest because the larvae find them particularly delicious.

The Maine Forest Service searches for nests of cerceris wasps and periodically checks to see what they’re capturing.

A piece of plastic is placed over the entrance to the nest. The plastic has a hole in it large enough for the wasps to get out, but too small for them to get back in carrying a snack.

When a wasp returns with a meal, the wasp is captured in a small net, and its food is taken from it. The wasp is released to go hunt again. Fifty meals are collected, then the plastic is removed from the entrance. If there are no emerald ash borers in the fifty samples, probably there are none in the area.

If, however, wasps have captured emerald ash borers, the Forest Service knows that there are ash borers nearby because cerceris doesn’t fly too far afield (or more aptly, awood) to hunt. Ash trees near the wasp nest are inspected for the green beetle. If any are found, the trees must be felled and chipped to prevent the infestation from spreading.

Biosurveillance is not the only method the Forest Service has to check for the presence of ash borers, but it’s a particularly effective one.

No emerald ash bores have been found in Maine yet, but they are working their way here and are close, as in New Hampshire close.

Cerceris wasps will be a powerful tool to help the Maine Forest Service know when the ash borer has arrived and to help locate and track the pest.