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Hundreds of flies in my bags of Roxul insulation. Is this a concern?

tom87| Posted inGreen Products and Materialson

Hello,

I stored my brand new roxul insulation ( still in wrapping) in the barn and has been sitting on a raised shelf for six months. I go to open all the bags to insulate today and there are hundreds of flies inside the bag, and alive. It’s almost like they were all drunk (I assume from the insulation smell). My donkeys use this barn and the barn has a lot of flies in general.

Is this something I should be concerned about using this insulation for my house? After I opened the bad they all flew out but concerned if they left eggs or something. I looked through several and couldn’t notice any eggs.

顺便说一下. .到底发生了什么事?我认为roxul预防this type of stuff? Has anyone experienced anything similar with roxul?

Hoping mice didn’t get in or something and poop…

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Replies

  1. John Clark||#1

    Roxul has only mentioned via customer feedback that pests do not nest in their product but they themselves does not warranty their product as pest-proof.

    I know of only one instance where squirrels nested in exposed Roxul batts which were stacked in what I believe was a garage.

    My two cents.

  2. tom87||#2

    Hi John. Yes, I have heard of some instances.. There was no signs of pests but I am concerned why so many flies where in there.

  3. GBA Editor
    Martin Holladay||#3

    Tom,
    It sounds like a group of cluster flies. Generally harmless. Unlikely to return to the same spot (especially once the insulation is installed). Needless to say, I'm just guessing.

    More on cluster flies:
    http://ento.psu.edu/extension/factsheets/cluster-flies

  4. tom87||#4

    Hi Martin. From my research, that's what I believe them to be as well. What I am baffled about, is why there were hundreds in the bag of insulation.. Usually that many flies wouldn't do that unless there was feces, flesh, etc.

    So i guess my main concern is if rat droppings or something else got in the insulation.

  5. GBA Editor
    Martin Holladay||#5

    Tom,
    Cluster flies crawl into little cracks during the autumn and just sit there. I think they are looking for a sheltered place to get out of the weather.

    You're right that their behavior seems "drunk." Compared to a housefly, a cluster fly is sluggish.

  6. tom87||#6

    Ahh that makes sense! Have you ever experienced something similar in your builds? And It's actually been very warm weather which is interesting..

    Not saying you are a fly expert (or maybe you are) but do you think I would notice eggs/rat droppings,etc in the insulation?

    And lets say the was dead flies,eggs,droppings in the insulation...Is that dangerous for me to breath or does it become harmless once sealed?

    Just trying to decide if I should ditch the insulation and get new stuff or If I am being overly concerned....

  7. tom87||#7

    Oh. And I did want to make note of this: I put up some of the insulation in the walls two days ago, came back in the house and there were hundreds and hundreds of flies in the house, mostly at the top of the ceiling. I've never seen anything like this. So either maggots turned into flies or the just really love the insulation...

  8. GBA Editor
    Martin Holladay||#8

    Tom,
    If there are rat droppings in your insulation, you will notice them. Assuming you look.

    Most Vermont builders -- homeowners, too -- know about cluster flies. We see them in the fall, and sometimes in mid-winter, if they decide to crawl out of a crack and start walking around. Double-hung windows in old houses tend to attract cluster flies -- often in attics.

    In some cases, cluster flies are visible in great numbers.

  9. tom87||#9

    Thanks for the valuable information Martin. That makes sense because they were all up around the windows.

    Just to clarify, you are basically saying that the flies were just looking for a place to stay warm? And as long as I notice no signs of droppings, you would advise that I keep the insulation and use it?

  10. GBA Editor
    Martin Holladay||#10

    Tom,
    I'm not there to inspect your insulation. I would proceed with common sense if I were you.

    If the insulation looks OK, I would use it. But the decision is yours. You're the one who can examine and smell the insulation.

  11. tom87||#11

    Cheers.

  12. Brian P||#12

    Before building our current house, I lived in an older leaky house that had cluster flies in the fall and other times. In larger numbers (we would sometimes vacuum them), they are visually unpleasant and kind of disgusting.

    I don't know the biology of these flies, but if installing the insulation in a house leads to a good chance of cluster fly infestation (due to eggs?), I would think twice. This of course depends on how much Roxul we're talking about. If it's just a select few bags, I would replace them.

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