What's That Bug? does not endorse extermination

Unknown Borer Beetle
Location: Rocky Mountain House, AB, Canada
October 20, 2011 12:24 am
I saw this beetle at the front entrance to the Visitor Center at Rocky Mountain House National Park in Alberta in June. I took the picture and went inside and asked if anybody could tell me what it was. One person walked outside and said it was a June Bug and to be careful as it may bite, then stomped on it. It doesn’t look like a June Bug as I remember growing up in Colorado. It has very much the shape of a Banded Alder Borer. Maybe 40 mm including antenna. Also, if you look closely around the thorax, does it have an infestation of lice?
At the Canadian border this week, I picked a brochure titled ”DON’T MOVE FIREWOOD”. Prominently displayed on the front of the brochure is, I think, a picture of this beetle, implying that it is some kind of invasive species, but it doesn’t identify it. What is it?
Signature: R. Reed

White Spotted Sawyer with Phoretic Mites

Dear R. Reed,
Your beetle is one of the native Longhorned Borers, specifically
Monochamus scutellatus, the White Spotted Sawyer which is named for the white scutellum, the triangular shaped marking at the base of the elytra or wing covers.  According to BugGuide, other common names include Longicorne noir in French speaking Canada and the intriguing names Oil Sands Beetle and Tar Sands Beetle.  Here is the BugGuide explanation for those names:  “The local (to Fort McMurray, Alberta, Canada) common names of Oil Sands Beetle and Tar Sands Beetle are due to the attraction of this insect to oil sands. Apparently the attraction is the scent of bitumen, chemically similar to compounds released by the diseased or damaged coniferous trees where they are attracted to lay their eggs.”
The infestation you mentioned are actually Mites, and we were at first uncertain if they were parasitic Mites or opportunistic Mites using the beetle for transportation purposes, a phenomenon known as phoresy.  We found a photo on BugGuide of a White Spotted Sawyer with Mites, but no explanation.  Additional research led us to an online article on the Canadian Entomologist website with the lengthy title:  “REVIEW OF MITES OF THE GENUS MUCROSEIUS (ACARI: MESOSTIGMATA: ASCIDAE) ASSOCIATED WITH SAWYER BEETLES (CERAMBYCIDAE: MONOCHAMUS AND MECYNIPPUS) AND PINE WOOD NEMATODES [APHELENCHOIDIDAE: BURSAPHELENCHUS XYLOPHILUS (STEINER AND BUHRER) NICKLE], WITH DESCRIPTIONS OF SIX NEW SPECIES FROM JAPAN AND NORTH AMERICA, AND NOTES ON THEIR PREVIOUS MISIDENTIFICATION.”  The article begins:  “Six new species of Mucroseius having adult females phoretic on adult sawyer beetles of the genus Monochamus are described,” and that was sufficient to indicate that these mites are interested in the beetles for transportation purposes, though we are curious as to the intricacies of the relationship between these organisms.  Alas, we have no time to delve deeper.
We are somewhat troubled by your experience at the Visitor Center at Rocky Mountain House National Park in Alberta in June.  We can’t help but to wonder if the person who misidentified this Sawyer, mistaking it for a June Bug and promptly stomping on it was a park employee.  That does not seem like appropriate behavior for a national park employee at a visitor center.  We suspect it was more likely another tourist.  The brochure on firewood is noteworthy.  Even native species can have their range expanded through human actions.

What's That Bug? does not endorse extermination
Location: Canada

4 Responses to White Spotted Sawyer with Phoretic Mites

  1. bmoc says:

    The mites are phoretic deutonymphs (next-to-last instar) in the family Uropodidae. Many uropodids live in decaying wood or the galleries of beetle larvae, so this association is commonplace. Mucroseius mites look rather different, being more elongate and having much longer legs.

  2. LuciteBrian says:

    We have some great specimens in lucite (necklaces) http://tinyurl.com/2czw659

  3. AB guy says:

    I am from alberta and, although I have no Idea the actual name of these beetles, I can say that I have always heard them referred to as June bugs as well. Due to their extremely painful bite and ferocious nature if disturbed (grabbing one by the antenna will elicite immediate reaching with strong snapping jaws that can be quite intimidating.), they may be the most feared insect here and as a result tend to get stomped on sight, especially ones that are unfortunate enough to land on an unsuspecting person. If you want to see someone jump and panick, flicking their hand wildly at it, point one out on their collar…

    As for the pamphlet, it may have been for northern pine beetle, which has devistated tens of millions of acres of timber across western canada in recent years.

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