New House Borer

2010 February 6

S_ caught this huge beetle for me near the end of July, I don’t remember if she caught it in the house, or outdoors[1].

I’m pretty sure it’s a New House Borer, Arhopalus productus. Once you get beetles this large, there generally aren’t a lot of possiblities, and the two dimples on the pronotum behind the head are supposed to be pretty characteristic of the species. If she caught it indoors, that wouldn’t be too surprising, because they are commonly found in new houses[2] within the first year after construction. They are one of the few wood-borers whose larvae infest dry, dead wood. Like, for example, piled lumber in a lumberyard.

So, what happens is some lumber (they usually prefer softwoods like pine) in a lumberyard gets infested, and the larvae burrow in. The lumber then gets used to build a house. Since it takes them two years to mature, any given larva stays there in the lumber for close to a year. Then it finally burrows to the surface, makes a hole in the wood, and emerges as this great big beetle.

They aren’t generally numerous enough to affect the soundness of the wood, so they only cause cosmetic damage – a hole suddenly appears in a wall, baseboard, or what have you. Luckily, they are pretty much done with your house after that point: the dry lumber built into a house is not sufficiently exposed or sufficiently moist for them to lay eggs on, and so they don’t. So, you can just plug any visible holes they make and be done with them.

They look to be pretty strong fliers, so they can travel quite a way. From the picture, I think that their bodies are long enough that they don’t have to have a hinge in the middle of the wing like a lot of other beetles do. So, they can pop their wings and fly pretty quickly, with minimal preparation.

I understand that practically all new houses are likely to end up with one or two of these beetles in the first year after construction, and they really aren’t anything to worry about.

[1] At the time, I was experimenting with taking pictures of larger insects in direct sunlight so that I could get a fast shutter speed, which I thought would help avoid blurring when they moved around (like they do). Overall, it didn’t give as good of results as I would like, the shadows are too pronounced and the lit areas tend to be washed out. Rigging up some sort of flash definitely works better than natural, undiffused sunlight.

[2] The relevance of this is that we’ve had a new house for somewhat over a year, now. I hadn’t mentioned it here before, but for a long time we’d been dissatisfied with our old farmhouse – it leaked air like a sieve, the foundations were kind of dubious (with holes large enough that snakes could get into the basement), it cost a fortune to heat, and the layout left a lot to be desired (its only real virtues had been that it had a good location, came with 9 acres of land, and had been pretty cheap to buy). Originally we thought about remodeling it, until it became apparent that a proper remodeling job would cost almost as much as just buliding a new house from scratch. And, as my father pointed out, if you remodel an old house, you don’t get a new house – you just get a remodeled old house, which isn’t worth nearly as much if you ever sell it. So, in the summer of 2008 we went ahead and built a new house just across the driveway from the old house. The new one is heavily insulated, partly earth-sheltered on the north and west sides to protect it from the prevailing winter winds, sealed airtight with an air/air heat exchanger for ventilation, and oriented so that on the days in the winter when the sun *does* shine, we get a pretty significant amount of solar heating[3]. The house was finished and we moved in just after Thanksgiving of 2008, and it is a tremendous improvement over the old one. Heating costs are now a fraction of what they used to be. And, of course, this particular beetle appeared the next summer, right on schedule if it happened to have been living in, say, a wall stud. It may not have come from the house, since they do live in the wild and it might just have been a coincidence. But, I think the timing is a bit suspicious.

[3] On sunny days in February, the solar gain is enough to heat the new house to as much as 80 F, even when it is below zero F outdoors. As opposed to the old house, which had essentially *zero* ability to pick up heat from the sun, and would be kind of cold inside up until about the middle of *June*. The way the old house was built, it was dark enough inside that we needed to turn on the lights *even at noon on sunny days in the middle of the summer!*. The new house also has roof overhangs that let the sun shine in fully in the winter, but block almost all of it in the summer, so the house doesn’t overheat in the summer, either. We worked with a local designer who has been building energy-efficient houses in this area for over 30 years, and with a contractor who has worked closely with him for a long time, and overall I think it was well worth it.

5 Responses
  1. February 6, 2010


    Sorry for taking the original topic off-track, but can you give more detail on this:

    On sunny days in February, the solar gain is enough to heat the new house to as much as 80 F

    Are you saying that the solar system can heat your house to 80F in the winter?! Or is it helped along by a gas heater?


  2. February 7, 2010

    Well, during periods in winter when the sun shines every day, the temperature peaks at about 80F, falls to about 70F overnight, and then back up after sunrise. During those periods, the house heating system never turns on, and the temperature is being maintained entirely by the solar gain. And this is passive solar heating, just from the sun shining in the windows – no moving parts are involved, so we don’t have to deal with the equipment maintenance issues that go along with a lot of active solar heating systems.

    Of course, this *is* Michigan, one of the most reliably overcast states in the Union, so in Febuary we only get sunny days about 1/2 to 1/3 of the time. So, the in-floor heating system does have to come on to maintain the temperature on the overcast days. Still, the house is well-insulated enough that the heating system doesn’t have to strain to maintain the temperature either. And the complete lack of drafts makes it *feel* warmer, too.

  3. February 7, 2010

    Very cool. Some day, I hope I can live in an intelligently-designed house like that!

  4. Cheyenne Wateridge permalink
    June 23, 2014

    One just landed on my head an I flipped out

  5. June 23, 2014

    Cheyenne – That’s understandable. These things are monsters compared to the run-of-the-mill insects we get around here.

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