Large Weevil – Oak Timberworm

2011 January 29

Here’s another specimen that Sam and Rosie caught for me when we went to Otter Lake on May 23, 2010. This fine, glossy beetle was about a centimeter long.

This is a good match for the Oak Timberworm, Arrhenodes minutus, which has larvae that burrow under the bark of dead oak trees (and also elm, poplar, and beech).

They are evidently sexually dimorphic, with the males having shorter, broader beaks with more aggressive mandibles at the tips, and the females having longer, quite slender snouts. This one has a noticeably longer beak than the other males shown on BugGuide, but its beak is substantially broader than the females that they show. Overall, I think I’ll go with it being an unusually long-nosed male.

The main ID feature is the nearly cylindrical body with deeply-striated wing covers, and elongated brown spots.

And, while processing these pictures, I kept seeing something stuck to the thick part of the right front leg. This is the best picture of whatever-it-was. It could be just a piece of dirt, but I think it is yet another mite either hitching a ride, or sucking the beetle’s body fluids.

Anyway, the Oak Timberworm is something of a pest of lumber, attacking trees through spots where the bark is damaged. It sounds like they don’t generally kill the tree, but they do damage the wood, burrowing directly into it. Sometimes they even attack cut lumber. The holes they make degrade the wood quality pretty substantially. And since they are attacking things like oak that are considered a more premium lumber, this can cause a rather marked loss of value.

5 Responses
  1. January 29, 2011

    Quite a cool looking weevil. Like the clean white background, a great way to look at the beetle unencumbered by background material.

  2. January 30, 2011

    Thanks. I’m always a little torn on the background – on the one hand, a clean white background is very nice aesthetically, but on the other hand it is nice to have something that can be used to show the size of the subject. Since I almost always have several pictures of each creature, I suppose the best approach is to try for at least one attractive picture, along with extras that show detail and scale.

  3. January 30, 2011

    The guy looks like a concept car. This one, perhaps?

  4. February 3, 2011

    Oh cool! I’ve been trying to find one of these for my own photographic agenda, but haven’t had any luck. It’s such a charismatic insect.

  5. February 4, 2011

    Alex: Maybe you need to recruit some 3-5 year old kids to find some for you. It worked for me!

    The girls really do seem to be better than me at finding insects. Maybe it’s because they are closer to the ground.

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