What is this odd powdery substance? (pics)

[Renee]

A few months ago we bought a piece of furniture from an antiques dealer here on Okinawa. Supposedly, the front pieces of this shelf thing are architectural details from an old building in India. The front pieces are teak, and very thick--about 4". The rest of the wood appears to be a random mix of old wood. He said it was teak, and it might be (lots of stuff is, here) but I don't know.

This light yellowish powder keeps appearing in certain places on the shelf. Two corners get it, and the top of the DVD player, which is under the central shelf, get piles of the stuff. You clean it up, and about 3 days later it looks like the photos. Oddly, if I wipe my finger on the bottom of the shelf that's over the DVD player, it comes up clean. Same with the other piles--the areas above them are clean. We've inspected the piece closely for insect damage, but we can't find any. If it's bugs, they're too small to see with the naked eye.

Other maybe-relevant info: It's humid as hell here, and hot. We have pets. This has never appeared in any other part of the house. The stuff has no odor; I haven't tasted it. It looks like super-fine sawdust, like you'd get if you were sanding wood with fine-grade sandpaper.

So, what the hell is this? And how do I get rid of it?

[Blake]

I don't think there's much doubt that it's frass from a woodboring insect, though at that resolution it's impossible to tell which.

You state that you've "inspected the piece closely for insect damage, but can't find any", but looking at this picture, even at low resolution, I can see numerous holes that could be the source. This isn't a particularly well made/maintained piece of furniture so there are ample hiding places for the exit holes.

You've got a few options.

You can sand the piece back lightly (I assume it's varnished) then paint it with a solution of mineral turpentine/kerosine and Permethrin or similar insecticide. That'll give you long term protection.

You can try wrapping it in black plastic and putting it out in the summer sun if it's warm enough. If you can get the temperature up to ~45oC for a few hours you'll role them without pesticides. Alternatively you can use a more open tent and some commercial hot air dryers to achieve the same effect. You can usually hire the hot air blowers cheaply. This gives no control of eggs, so expect to retreat in a few months. It has the advantage that there's no residue, no smell and no sanding and re-varnishing.

Or if you can get ahold of some Dichlorvos you can tent it and fumigate it. Limited residue, no sanding but limited long term control. You may not be able to buy Dichlorvos off the shelf where you are but most localities sell it in sealed units for killing flies in bins. These work fine but are a bit more expensive.

Or you can call in a professional exterminator who will then use one of the above options

[Bosda Di'Chi of Tricor]

Act quickly--these things might wind up in the walls of your home if you do not.

[Renee]

Thanks, guys. We might try the heat thing--it's really hot here, anyway, I'm sure we could get it hot enough. But when would we have to re-treat? Unfortunately, we're using the thing as an entertainment center, so whatever we do is going to be a pain. Plus, getting insecticides--I might just try to order them from the US. I'm actually not sure it's varnished. The front pieces definitely aren't, but those aren't the buggy ones. Actually...it might be easier for us to just dissemble the (as you say, badly-built) shelf and get rid of the three pieces that have bugs, and hope it hasn't spread. Hmmm...will talk to the husband. We were thinking of tearing it down eventually, anyway, since we really bought it for the antique front details.

The house is concrete, Bosda, so at least that isn't much of a danger, although I'm sure we'll be moving into a stick-built when we go back the States in a few months.

Again, thanks for the quick and very helpful responses!

[Blake]

Originally Posted by Renee

.... when would we have to re-treat?

That depends a lot on the insect involved. The general rule of thumb is 16-20 weeks to allow all eggs to hatch without allowing any adults to emerge.

Plus, getting insecticides--I might just try to order them from the US.

Are pyrethroids that hard to buy in Japan? Most countries sell the stuff in every hardware store.

I'm actually not sure it's varnished. The front pieces definitely aren't, but those aren't the buggy ones.

I'd be inclined to treat the whole unit just to be safe. These things move, and while they may prefer the other pieces they might move into the front pieces when they've eaten out their old home.

[Renee]

Originally Posted by Blake

That depends a lot on the insect involved. The general rule of thumb is 16-20 weeks to allow all eggs to hatch without allowing any adults to emerge.




Are pyrethroids that hard to buy in Japan? Most countries sell the stuff in every hardware store.



I'd be inclined to treat the whole unit just to be safe. These things move, and while they may prefer the other pieces they might move into the front pieces when they've eaten out their old home.

I don't know about pyrethoids. I'd have to get a translation into Japanese of it, and then try to find it in the hardware store. It can be pretty hard to get things here that are easy to get back home.

Isn't teak insect resistant? I know the teak front isn't varnished, and none of the buggy areas are near it right now. I'm tempted to treat the teak (and the rest, but not worry about sanding down, etc,) and then when we move in a few months to tear the shelf apart and just keep the teak front pieces.

[Blake]

Originally Posted by Renee

Isn't teak insect resistant?

Teak is insect resistant, not insect proof. And unless you really know your timber you're placing a lot of faith in it being genuine teak.