Insects and Spiders - native

Banded Alder Borer (Rosalia funebris) on Aug 8, 2025

Submitter does not have a specimen

Description of specimen

Appears to be a Rosalia longicorn beetle, or species.very similar in color. Appeared to be female as antenna were not twice as long as the body, per Wikipedia description of the insect. See similar sighting for blue beetle with black and white on body and antenna was reported in Portland area in July.

Commentary

Thank you for your report! The color and pattern on the Banded alder borer (Rosalia funebris) is unique. I'll bet your ID is correct even though you didn't get a photo for confirmation. They are among our most striking and beautiful native beetles. It must have been arresting to see one in flight. Banded alder borers are not pests. Their grubs live in dead branches of red alder and some other forest trees. They seem to be very abundant this year as we have had many reports.

Tom Valente
Aug. 11, 2025, 3:07 a.m.

Resources

Information from Banded Alder Borer from Oregon State and iNaturalist.

Location

Was entering restaurant and beetle flew lazily by. Coloring was highly unique, so decided to report site. Location was on Spruce Street, about 40 feet from intersection of Spruce and Railroad.

Expert Reviewer

Tom Valente
Oregon Department of Agriculture

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