white-spotted sawyer

not listed

NNR - Unranked

not listed

White-spotted sawyer is a moderate-sized, shiny black, wood-boring, long-horned beetle.

The adult female body is robust, broad-shouldered, ¾″ to 11 ⁄16″ long, and 3 ⁄16″ to ¼″ wide. There is a large, blunt projection on each side of the hardened covering of the thorax (pronotum). The hardened forewings (elytra) are shiny black, have a metallic appearance, and have small patches of white hairs. The small triangular plate between the bases of the elytra (scutellum) is covered with white hairs.

The face is nearly flat. The antennae are black, are longer than the body, and project from a notch in the eyes. When they are held back along the body the last two or three segments extend beyond the elytra. Two segmented feeler-like structures (palpi) are attached to the lower jaw-like structures (maxillae). The last segment of each maxillary palp is pointed.

The legs are reddish-black. The forward, middle, and back legs each have 5 end segments (tarsi). They appear as 4 segments because the minute 4th segment is concealed by the enlarged 3rd segment.

The male is similar to the female but smaller (not including the antennae). The elytra do not have patches of white hairs.

¾″ to 11 ⁄16″

Fire-damaged coniferous and mixed forests

June to September

Adults emerge in June or later depending on the weather. After mating, the female chooses a suitable location away from direct sunlight on the side or bottom of a dead or dying host tree or log. She then chews a slit into the bark and lays one or sometimes more eggs in the slit. Egg laying begins in early June and continues to early September.

The egg hatches in 9 to 14 days. Within three days the larva tunnels into the cambium where it feeds until mid- or late summer. It then tunnels into the wood where it overwinters. In the spring it continues tunnelling, usually turning back toward the surface and creating a U-shaped tunnel. When it nears the surface it creates a pupal cell and plugs the end of the tunnel. It overwinters as a prepupa. In late May or June of the following spring the larva pupates. Two weeks later the adult emerges.

In northern Minnesota this cycle requires two years. Farther south it may take only one year.

Dead or dying wood of conifers, especially eastern white pine, but also red pine, jack pine, balsam fir, white spruce, and black spruce, and occasionally tamarack.

Needles and the tender bark of twigs of conifers.

Sources

7, 24, 29, 30, 72.

Common and widespread

There are two subspecies on Monochamus scutellatus. Only the nominate subspecies, Monochamus scutellatus scutellatus, occurs east of the Rocky Mountains.

Found on my screen door.

They bite!

Location: Augusta County Virginia

he likes to talk alot

Location: Potassium St., Ramsey, MN

Mary Katherine May
4/3/2022

Location: Littlefork, Koochiching County MN

Location: Woodbury, Minnesota

Location: Wrenshall, MN

Location: Aurora, MN    St. Louis County

Are these really harmful to trees?  This one flew into the house.  We captured and released.  However, with trees lining the streets and being next to a city park with many pine trees, we are wondering if we should have disposed it instead.

These beetles are found especially in forested areas that have been recently burned. The female lays eggs in dead or dying wood. The damage is a concern to the logging industry because the larvae tunnels damage the wood. This boring beetle is not a threat to healthy trees.

Location: Cass County

Found on my screen door.

Location: Bemidji, Minnesota

Location: Park Rapids, MN

Location: Monticello, MN

Location: Cass County

Location: Duluth MN

Location: St Louis Co MN

They bite!