Does Vacuum Kill Insects?

      Nope, you need heat to kill bugs in wood (and don't call them bugs). March 4, 2009

Question
In theory using a vacuum press with 1700psi should crush or blow up any living thing within wood. Any takers on this subject? This is something that would save me a fortune if it works. I work exclusively with reclaimed lumber so powder post beetles are a large problem.

Forum Responses
(WOODnetWORK Forum)
From Gene Wengert, forum technical advisor:
A vacuum within the wood will not kill any eggs. Neither will pressure.



From the original questioner:
Gene - I've been reading a lot of your posts about chemicals and heat. Chemicals are killing the budget, and seem to be a waste of money according to what I have been reading. The closet kiln available is 100 miles from here and I have well over 15,000bft of lumber. I thought that vacuuming as I use would be great. So this brings in two questions.

1. Why would vacuuming not create enough pressure to kill bugs within the wood?

2. Exactly how long do you have to keep the wood at 135 degrees to kill effectively?



From contributor J:
There's no such thing as a vacuum press that creates 1700 psi. All a vacuum press does is bring the weight of the atmosphere to bear on whatever's in the press, which means somewhat less than 15 PSI depending on elevation. Perhaps you're thinking of pounds per square foot? That would be about right. Anyhow, that pressure only bears on the surfaces of stuff in the press where they are touching the membrane or platen; it doesn't somehow transfer all through the pressed material. If a vacuum were to kill bugs buried inside a piece of lumber, the only ways it could do it would be through either oxygen deprivation or if the reduction in pressure caused their bodies and/or eggs to rupture. I don't know enough about their biology to say how powder post beetles survive such circumstances, but it sounds from Gene’s comments that they can.


From contributor W:
If the bugs are in the wood the only way to kill them with pressure is to crush the wood and that isn't an option. 130 df core temp for a minimum of four hours is about the cheapest and safest way.


From the original questioner:
Thanks folks. It's time to build a large oven for the winter. Any good ideas or other posts you can direct me? Contributor J - yes I meant 1700 psf sorry.


From contributor K:
I did a little test once, just for fun. I was vacuum bagging some veneer panels, and wondered what would happen to insects in that rare atmosphere, so I caught an assortment, and put them in a jar/filter in the air-line. They all seemed pretty excited, or agitated initially, then stopped moving after about tne minutes.

It was cool weather, and since I was using epoxy, I held the vacuum for about eight hours. When I released the vacuum, I was fairly certain that all were dead, but I left them out where I could see them. After about six hours, while walking by, I noticed the antenna of the cockroach twitch. I tickled it and sure enough, that darn thing had survived, and started getting back to normal. I normally pull about 28" Hg.



From contributor S:
Yep, low pressure, high pressure, water, a roach will survive them all!


From Gene Wengert, forum technical advisor:
It might be a good idea if we become a bit more careful about the use of the term "bug."
A bug is a special insect in the phylum Arthropoda, class Insecta, order Hemiptera. Hemiptera means "half wing" and refers to the fact that part of the first pair of wings in a true bug is toughened and hard, while the rest of the first pair and the second pair are membranous.

Although bugs vary greatly in size, color, and physical appearance, they all have modified piercing and sucking mouthparts in the form of a jointed beak. Most species suck plant juices; however, some suck the blood of other insects and spiders; others, such as the bedbug, feed on people and other animals. Many of these insects characteristically secrete defensive substances (e.g., the stinkbug).

So, in dry or partly dry wood, we really do not have bugs, but have wood boring insects. If we want to be sloppy, we can call them bugs, but a more precise name would be "insect." And this concludes our lesson for the day. This info may be covered on the final exam.



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