Metallic wood-boring beetle – Dicerca

2009 May 23

I found this on campus, clinging to the side of the Electrical Engineering building, so I put it in a pill bottle and brought it home to photograph:


It was just about 2 centimeters long, and had a strong metallic sheen, particularly on the underside.


It looks like a Metallic Wood Boring Beetle, in the genus Dicerca. It looks a lot like either Dicerca divaricata or Dicerca tenebrica.


As you might expect from the name, the larvae bore into wood. Some species can infest healthy trees, but most of them attack weakened, dead, or recently felled trees.

There are a number of insects that bore into wood, but they aren’t necessarily eating the same things. Some, like termites, have very effective gut microorganisms that let them digest cellulose directly, something that is very hard to do. Other insects have less-effective gut organisms, and digest cellulose less effectively. Others eat fungus that is growing on the wood, while still others chew up the wood to extract sugars and other nutrients, and just leave the cellulose and lignin behind. It looks like the metallic wood-boring beetle larvae are only indifferently good at digesting cellulose. From the descriptions of what they do, it sounds like they essentially chew up the wood, stripping apart the lignin and cellulose to free any trapped nutrients. Then they sort of lick off the sugars and proteins, leaving behind sawdust that they pack behind them into the hole that they made in the wood. They prefer the sapwood (the wood just under the bark) because this is where the nutrients are, leaving the dead wood in the center of the tree for other things to digest. The larvae are odd-looking things, with a broad bit just behind the head that gives them sort of a hammer shape. I’m not sure what, if anything, the adults eat, but pollen and nectar seem to be pretty common diets for these sorts of things.

5 Responses
  1. May 23, 2009

    very cool looking beetle 😀

  2. May 26, 2009

    Awesome! Good photos. Did not know how they digested the wood, etc.

  3. May 26, 2009

    Thanks! I’ve been looking into how various things go about digesting wood, and it turns out that the only organisms that are particularly good at it are certain fungi and bacteria. Animals that “digest” cellulose, like termites and ruminants, actually just have a symbiotic relationship with microorganisms in their stomachs that do the heavy work. Those of that can’t do this, can always use fungi for sort of “external digestion” of the cellulose. Sometimes I wonder whether it would be practical to make a fermentation system where you shovel in cellulose wastes (wood scraps, grass, corn stalks, you name it), and extrude a food product that humans could digest. Then I remember what it smelled like when a cow would belch in my face, and realize that this is about what the fermenter product would probably smell like. And I drop the idea. At any rate, growing oyster mushrooms on moist paper works pretty well, and smells a whole lot better.

  4. May 29, 2009

    Tim, if they have microorganisms in their stomachs to perform some of the stages of digestion, does this mean that the food sits there for a while to give their partners a chance to work?

    By the way, that’s a very handsome beetle in the photo. Well done!

  5. Debbie Ott permalink
    August 27, 2019

    Do they make any sounds? Thank you

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