An invasive beetle species notorious for decimating ash tree populations in North America is spreading in Canada, leaving 20 million dead trees in its wake.

The Asian ash beetle (Agrilus planipennis), known by its acronym EAB, attacks all 16 ash species in North America and has so far destroyed hundreds of millions of ash trees.

The small metallic-green beetle, native to East Asia, was first discovered in Oregon in 2022. Since then, extensive tests to limit the damage have been unsuccessful.

Ash is valued for flooring, furniture and other high-quality wood products and is traditionally the choice for making baseball bats, oars, skis and other sporting goods.

The Oregon ash is a native tree and is found in the valleys of the Pacific Northwest, along rivers and in moist locations. In fact, its resistance to standing water allows this tree to grow on the most poorly drained valley floors where no other tree species thrives.

With more than 70,000 ash trees on public land and many more on private property, the insect poses a serious threat to treetops in cities.

“No state has been able to eradicate EAB, so we have expected since it was first discovered that it would eventually appear in new parts of Oregon,” said Cody Holthouse, compliance and regulatory manager for the Oregon Department of Forestry.

“That’s why staff from the cooperating agencies have been systematically searching for the insect, setting traps outside the known infestation area and training people to recognize the signs and symptoms of an infestation. This will help us find out where the insect is spreading.”

The borer’s larvae bore into the bark of ash trees, causing crown dieback and eventual death of the tree. The 1/2-inch beetle, half the size of a $2 coin, is often difficult to spot, especially in newly infested trees.

The extent of the dieback suggests that the EAB may have been present for many years but went unnoticed due to difficult access and dense vegetation, which includes a mix of oaks and conifers.

The borer’s larvae bore into the bark of ash trees, causing crown dieback and eventual death of the tree. The 1/2-inch beetle, half the size of a $2 coin, is often difficult to spot, especially in newly infested trees.

Signs of infestation include thinning and yellowing leaves, bark cracks, D-shaped holes in the tree bark and basal shoots.

This quarantine will hopefully restrict the movement of various tree materials including, but not limited to, logs, green cuttings, nursery plants, scions, bud wood, wood chips, mulch, stumps, roots, twigs, and firewood of hardwood species.

“We want to protect the rest of Oregon for as long as possible to give communities more time to prepare,” said Cody Holthouse.

A favorite among botanists, the Emerald Jewel Beetle is quite a striking insect. The insect has a spectacular and shimmering pair of wings that catch the light and reflect an almost unnaturally bright green. Beneath these wings lies a magnificent purple abdomen. And as if that wasn’t enchanting enough, the Emerald Jewel Beetle’s face looks almost exactly like that of a classic science fiction alien, with large, black eyes taking up half of its head.

“By the time this masterpiece of evolution is discovered, it will probably be too late for the ash trees,” says Emma Hudgins, an ecologist at the University of Melbourne. The insects lay their eggs under the bark of the tree, where they hatch about a week later. These larvae feed under the bark and slowly dig winding tunnels just below the surface of the tree.

Eventually, the ash jewel beetles pupate, transform into their adult form, emerge from the tree and fly away in search of a mate so that the next generation can start the cycle all over again!

For an ash tree, this process can be fatal. Trees transport nutrients and water through their bark, and by drilling holes in this bark, the ash borers separate the tree’s roots from its branches.

“This essentially cuts off blood circulation in the tree,” said Dr. Hudgins.