Is this black-and-white bug an invasive forest killer or harmless look-alike?

While the geeks are on vacation, the geeklets are running the show. Herewith, a post from Laura’s daughter, Adelaide, age 12:

During our trips to the West Coast, my brother and I enjoy playing on the rock beach at our grandparents’ house in the San Juan Islands. The other day, we noticed a rather frightening, large, black and white insect with very long, striped antennae on the driftwood. We didn’t think twice about the creepy bug until another encounter the next day—it flew up in my face before touching down on a log.

This time, we decided to do some research. In all  the excitement, we couldn’t remember the exact details of how it looked, so we searched the Internet for black and white beetles. Up came a picture of an Asian Longhorned Beetle.


“That’s it!” we said. Then we went, “Oh, no!” This invasive species  causes millions of dollars in damage each year by boring into trees, often killing them.  They have been a huge problem in New York, Chicago, and New Jersey.

We decided to report the bug siting to the Washington Invasive Species Council through an online survey  on their website. The next day, the Council’s Wendy Brown emailed back to ask if the bug might be one of the native look-alikes that live in the area. Perhaps the Whitespotted Sawyer (top) or the Banded Alder Borer (bottom):

whitespotted sawyer banded alder borerWe weren’t sure, so we went back to the beach and hunted around until we found one of our beetles, and this time we took a picture:

beetle 002

We noticed that instead of having the distinctive array of random spots of the Asian Longhorned Beetle, it had chunky stripes. We determined it was a Banded Alder Borer, after all — whew!  These bugs have many interesting traits—adults are attracted to the smell of paint, and their larvae are most commonly found in dying, stressed, or recently felled conifers. They are on the front lines of nature’s recycling system, breaking down trees that have already met their end — unlike the Asian Longhorn, which will  just as soon attack a perfectly healthy hardwood.  The Banded Alder Borer is an exotic looking bug, and does not seem the kind that would be living in this environment since they would seem to stand out, but they do anyway.

3 thoughts on “Is this black-and-white bug an invasive forest killer or harmless look-alike?

  1. We found one of these Banded Alder Borer in the driveway! We had recently cut down conifers so this post is exceptionally helpful

  2. I’ve lived on the same forested piece of property in western Washington for 25 years, and I’d never seen one of these. Roughly 6 weeks ago, I felled about a dozen Doug firs and Western Red Cedars, and have yet to clean them up. I found one of these on my deck this afternoon.

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