bluish borer

not listed

NNR - Unranked

not listed

Bluish borer is an exotic, robust, small, wood-boring beetle. It is native to Europe and northern Asia. The first sightings in North America occurred in 1920 in Sturgeon Bay, Wisconsin, and in 1921 in Sherborn, Massachusetts. At both sightings they were reported as abundant. The beetle now occurs in the United States from Maine to Virginia, west to Minnesota and Missouri, in western Washington and Oregon, in southern Canada from New Brunswick to Manitoba, and in western British Columbia. It is uncommon in Minnesota, where it reaches the western extent of its range. Larvae hosts include honeysuckle (Lonicera spp.), snowberry (Symphoricarpos spp.), and buckthorn (Rhamnus spp.). The larvae bore under the bark and feed on the sapwood of living branches and twigs, eventually causing these parts to die. However, the beetle does not occur in large enough numbers to be considered a pest of significant concern.

Adults are 3⁄16″ to 5⁄16″ (5.2 to 7.8 mm) in length. The body is rigid, bullet-shaped, narrow, and long. The upper side is hairless, metallic, slightly shiny, and uniformly blue, bluish-green, bluish-violet, or rarely bronze.

The head is slightly tucked beneath the first segment of the thorax (prothorax). The antennae are short and have 11 segments. Segments 4 through 11 are sawtoothed. Segments 7 to 11 are as long as wide. The mouthparts are projected downward.

The upper plate covering the prothorax (pronotum) is wider than long, is narrowed in the middle, and has a distinct lateral margin. The lateral margin is rounded. There is no ridge on each side near the rear corners, and there is no longitudinal depression down the middle. The plate between the wing bases (scutellum) is small but visible. It is not crossed with ridges.

The abdomen has five segments. The first two segments are fused together. They are barely visible or not at all visible at the sides. The wing covers (elytra) are slightly narrowed before the middle and tapered beyond the middle toward the tips. They almost cover the entire abdomen. Toward the tip the inner margins are slightly elevated. The tips are separated and rounded. The surface is sculpted like shingles on a roof. The last segment of the abdomen does not have a distinct ridge above.

The last part of the leg (tarsus), corresponding to the foot, has 5 segments. There is a pair of claws at the tip of each tarsus.

Total length: 3 ⁄16″ to 5 ⁄16″ (5.2 to 7.8 mm)

Honeysuckle (Lonicera spp.), snowberry (Symphoricarpos spp.), and buckthorn (Rhamnus spp.)

May to July

Adults are good fliers.

Sapwood in the twigs and branches of host species

Leaves of the same plants as the larvae

Sources

24, 29, 30, 82, 83.

Agrilus cyanescens bluish wood boring beetle

Agrilus cyanescens, bluish borer, at the hedgerow at Barnes Prairie, Racine Co., WI. Photo taken May 31, 2021.

Location: Woodbury, MN

Location: Woodbury, MN

Location: Barnes Prairie, Racine Co., WI