Bugs in my ash lumber ???

[Bob Jones]

I have been noticing some new "features" on my ask workbench. I suspect bugs, what do you think? The wood was all kiln dried, but I have heard that there can still be bugs. I only notice it on the top, not on the legs or bottom. Any suggestions? How would I kill them?
Any help would be appreciated. I hate to cover with poly because I don't want it to be slippery.

[Butch Edwards]

..those are more than likely Emerald Ash Bores,which are killing all the ash trees just about everywhere..I had a friend make a 2" thick ash slab tabletop, that did the exact same thing..
he ended up applying poly over it cuz there's no way to stop the remaining bores from drilling out...except cover with a hard finish.

[Dan Andrews]

These holes also look just like the kind left by powder post beatles. The holes and trails in the right hand photo look like they were there before the lumber was milled. Powder post beatles will leave trails under bark, but not on the bare surface of wood. They love oak, and will also infest other hardwoods. They also spread like crazy. Fortunately I have seldom seen them in soft wood. You should check your lumber pile and isolate any boards showing these holes.

I did successfuly kill them once in an oak beam in an old garage. I mixed used motor oil and kerosene and painted the beam heavily with it. I doubt you will want to do that to your bench. Hopefully someone with knowledge of extermination chemicals can give you good advise.

[Deane Allinson]

I made a large coffee table out of 8/4 Ash. Later we found "sawdust" on the carpet. Same thing bore beetles. In south Texas there were always people around that made sausage for sale. I called one that had a large freezer. We stuck the table in the freezer for two weeks, and now no bore beetles. I didn't know how cold his freezer was set but it worked on 8/4. I saved the table. You don't want an infested piece in your house, they will migrate to other wood species too.

Deane

[Lowell Smith]

Apparently, the Emerald Ash Bore leave a "D" shaped hole. Not sure about the powder post beatles, but this might help you differentiate.

I wonder if you can't try sealing the wood with epoxy (see for example George Wilson's comments) instead of layering up Poly on the surface.

Good luck.

[Mike Brady]

The mill where I bought my ash for my workbench suggested using denatured alcohol as a way to kill the critters. I don't believe those are emerald ash borers....at least you had better hope they aren't. Those borers have killed millions of ash tress in Michigan and other states as well. Some places are cutting ash trees before the borers arrive. Those little trails are from the powder post bugs, if I'm not mistaken, but they can stay alive in hardwood for quite awhile.

[David Keller NC]

Bob - There are several ways to kill "in situ" wood borers. One is sealing the surface, but I can understand not wanting to do that to a bench. Here's another way - take your bench outside when you'll have a couple of rain-free days and place it on a surface that has no growing plants that you wish to keep (the treatment will kill all living things under the plastic). Buy some cheap painter's plastic at the Borg, and a bottle of janitorial strength ammonia from Ace Hardware (theoretically, cleaning ammonia from the grocery store will also work, but it's much weaker than janitorial strength, so it may take longer).

Drape the plastic over the bench so that a few inches is laying on the ground all around the bench. Pour the janitorial strength ammonia in a shallow plastic pan - be careful; a snootful of the fumes will do some serious damage. Cover the 2 or 3 inches of the left-over plastic with some soil, sand, or gravel so that a gas-tight seal is formed. Wait at least 12 hours - the ammonia fumes will kill everything. Take the cover off, let the bench "air" for a couple of hours and move it back in - presto, no more bugs.

Note that ammonia fuming will darken your bench somewhat, but this treatment is kinder to any metal fixtures you have on your bench versus chlorine gas treatment. It also leaves no residue versus pesticide treatment.

[Jim Koepke]

be careful; a snootful of the fumes will do some serious damage.

I used to work on blue printing equipment and can verify that ammonia can do some nasty things to living things.

We used to keep powdered orange juice or other citric drink handy to help counteract the effects of getting a snootful of the fumes.

jtk

[Tom Vanzant]

If the piece will fit in your microwave, a few 15-second cycles a minute or so apart works fine. Don't let the piece get too hot to handle comfortably.

[ray hampton]

it the piece will fit in the microwave, WHY not buy a microwave powerful enough for a 20 by 20 foot room and you could treat all of the ash wood by the skid load

[Phil Thien]

Sounds like you got a bug up your ash.

Are you absolutely certain that they are new holes? Kiln drying takes care of the bugs. Lumber suppliers are typically pretty careful about hitting the temps needed to kill the bugs.

Of course, dehumidification kilns may be something different. Where did you buy the lumber?

Also, as someone else said, the trails wouldn't normally happen at the surface. Trails are exposed during surfacing. Once the bugs out out, I believe the leave.

If they are new and you really want to get rid of them, wrap the piece in black plastic and leave it outside in the sun in the dead of summer for a few hours. Use a thermometer with remote to make sure the temp in the center gets hot enough. There is information out there on this, others have done it.

Heat does it. I had thought freezing doesn't, as the larvae can survive freezing (I believe).

Of course, high heat could cause other problems, too, with glue lines, etc.

[Jon van der Linden]

it the piece will fit in the microwave, WHY not buy a microwave powerful enough for a 20 by 20 foot room and you could treat all of the ash wood by the skid load

There are commercial microwave lumber kilns.

To the OP, to kill insects and beetles you don't need to get the wood terribly hot, once you get up to about 130 F they won't last very long at all (for many problem insects like termites, 130 F will kill them in minutes). 130 isn't very hot, just figure out what the most convenient way is to heat the wood for a short period of time.

[Bob Jones]

Thanks for the tips. The bench is 9 ft long and I have 2 vises on it. I was really hoping for a simpler solution like spraying it with something. I guess that is not an option.

Yes, I am certain that the holes are new. The hardwood dealer is reputable, a lot of retail stores and cabinet shops buy from him.

[Michael Titus]

Unless you are seeing fresh, loose "frass" (sawdust-like droppings) I would assume that the holes are old. Reputable dealers sell plenty of wood with old (inactive) insect damage.

[John Smithe]

the dec code in NY state to treat wood for ash borers is...

Only firewood labeled as meeting New York's heat treatment standards to kill pests (kiln-dried) may be transported into the state and further than 50 miles from the firewood's source. Acceptable firewood heat treatment must raise the core temperature of the firewood to 71 degrees C, or 160 degrees F, and hold it there for at least 75 minutes. Most "kiln-drying" processes that reduce the moisture content to less than 18% achieve this sterilization standard.

and it says that moisture drying will NOT kill the beatles

[john brenton]

Super bummer. I used to import musical instruments from south america. And when it came to ecuadorian imports sometimes I'd get some invisible devils that would leave these tracks wherever it fed, and just when I thought it must be dead or gone I'd find more ultra fine dust. Sonuva...I'd inject liquied death into the hole and see what happens.

[Jonathan McCullough]

I came across a nontoxic wood treatment that is supposed to do everything, essentially a solution of Borax and water. It is antifungal and insecticidal. It's not toxic to humans but Conservationists have been using it on Historic Register houses, especially in the South, by creating a solution, dipping timbers into it for a while, then pulling them out and letting them dry. The wood fibers suck up the salts along with the water, where the salt is deposited, not unlike petrified wood. Borax is fungicidal, and interferes with the enzymes that termites and carpenter ants have in their digestive tracts, so they essentially starve if they eat any of the treated wood. Borax also kills any plant life, so it's not like you can go around and sprinkle it around the garden--it will kill everything quick. Beyond that, there's little information available on the web.

[Jon van der Linden]

The chemical solution i.e. borax, or whatever, needs to actually come in contact with the bugs. Most of these borer grubs will simply not come into contact with a topical solution, and they will survive. Heat is the most effective solution.

The other issue is that if anyone were ever to use the wood for something else, it has chemicals in it. Where will those chemicals go then?

[David Keller NC]

Thanks for the tips. The bench is 9 ft long and I have 2 vises on it. I was really hoping for a simpler solution like spraying it with something. I guess that is not an option.

John - there are certainly some things you can spray that will kill powder post beatles, but they're generally not something you'd want inside your house, particularly around your little one. Borax solutions are definitely the way to go to prevent kiln-dried lumber from getting powder post beetles in the first place, but it's not going to help much once the beetle larvae are inside the wood.

Given the difficulty of heating your bench to 160 F, or dipping the whole thing in a solution, your best bet is going to be a fumigant. I wouldn't necessarily recommend doing ammonia fuming inside, but if your shop is an attached garage, or in a basement with windows or doors and with a concrete floor, you can get away with it. Ammonia isn't toxic in the way that something like malathion is - it leaves no residue. And so long as you provide sufficient ventilation to avoid building up a high concentration of fumes when you take the plastic tarp off of the bench, you've no worries. After all, ammonia is something that's used regularly to clean floors in human-habitated buildings.

You can also do the same with chlorox, but the same precautions apply. A snootful of fumes from a concentrated chlorix solution will be just as damaging as a snootful of ammonia vapors.

[David Weaver]

Heat is the only way I know of. Boric acid on the surface will kill anything that bores through the surface, but it won't get the bugs farther in - it's a better treatment for new wood to prevent holes.

I have seen some places in the last two years where 8/4 ash was 1.50 a board foot because of all of the trees dying or dead. Unfortunately, none of the suppliers around here seem to be abiding by that price schedule, because it's a good bench material at that price.

One of my planemaking books suggests against it because "it gets brittle as it ages", but I can't believe any bench parts receive enough stress for it to matter.

[Phil Thien]

Given the difficulty of heating your bench to 160 F, or dipping the whole thing in a solution, your best bet is going to be a fumigant.

How far will that penetrate the wood?

[JohnT Fitzgerald]

Given the difficulty of heating your bench to 160 F,

Agreed....but if I had this issue, I'd certainly try. I would make a large box out of the 2" rigid foam insulation (maybe even 2 layers), making sure all the seams were taped; some sort of heating element; and a remote thermometer to track the temp. maight take a while (a week?) for the interior to reach 160. You might be able to mock-up something to get a temp sensor inside a block to track it that way.

[David Keller NC]

How far will that penetrate the wood?

If you mean ammonia (the fumigant), it depends on the concentration of the fumes, the temperature and how long you leave it in the tent. For raw wood, about 1/4" deep over a 12 hour period is a rule of thumb.

But - that's for the solid wood. It will completely and totally penetrate the airspace in any insect holes in the wood. Generally that takes a couple of hours, but as the wood is "destroying" the ammonia that diffuses into the pores by oxidizing, one would want to leave a stack of wood (or an infested piece of furniture) in the tent for 6-12 hours. The wood on the inside of the insect tunnels will stop taking up the ammonia as the surface reacts, and the concentration in the pores will equalize with the bulk concentration in the tent. After a few hours, absolutely nothing will be alive, with the possible exception of fungal spores that have penetrated the stomata (pores) in the wood.

Chlorine is a bit trickier - it's so reactive that a substantial fraction of what's placed in the air space of the tent may be "used up". Nevertheless, it's effective. I generally prefer ammonia because it leaves metal surfaces undamaged except for superficially tarnishing brass, and the piece or stack of wood will "air out" faster.

There are other fumigants that are faster - a couple that come to mind are ethylene oxide and vapor-phase hydrogen peroxide, but neither is safe or practical for a home woodworker.

[ray hampton]

if the table are exposed to the ammonia fumes for 24 hours, how long will the ammonia smell remain in the wood if the table are taken indoors as soon as it are remove from the ammonia bath

[David Keller NC]

if the table are exposed to the ammonia fumes for 24 hours, how long will the ammonia smell remain in the wood if the table are taken indoors as soon as it are remove from the ammonia bath

That depends a lot on whether what you're fuming is raw wood or finished wood, what the temperature and humidity is, whether there's good ventilation in the room, etc... It also depends on how good your sense of smell is. Generally, I allow raw wood to set overnight outdoors to allow the ammonia to dissipate.

One final though, guys - if you're doing this to a piece of furniture and it's finished with shellac, the ammonia may destroy the finish. Also, raw wood that has a lot of tannins in it may darken appreciably. In fact, ammonia fuming was used to intentionally darken arts & crafts furniture made of oak at the turn of the 20th century.

[Jessica Pierce-LaRose]

Okay, i'm nervous of bringing lumber into my house I can't guarantee has seen a kiln. What about reclaimed wood? I mean, if I'm looking at repurposing 100+ year old barn beams or framing lumber, and it's still intact now, is it safe(ish) to assume it's not crawling with critters?

[David Keller NC]

Okay, i'm nervous of bringing lumber into my house I can't guarantee has seen a kiln. What about reclaimed wood? I mean, if I'm looking at repurposing 100+ year old barn beams or framing lumber, and it's still intact now, is it safe(ish) to assume it's not crawling with critters?

No, not really. A lot depends on what the wood is (species), where the wood was recovered and how it was handled since then. Powder post beetles don't generally attack walnut heartwood or heart pine, but do attack old red oak, white oak, maple, ash, hickory, cherry, and other common north american species.

But, it would be a shame to discard wonderful old growth reclaimed lumber just because it hasn't seen the inside of a kiln. In fact, I go out of my way to find lumber that hasn't seen the inside of a kiln - I just fume it before I take it into the shop.

And, I'd note that kiln-drying doesn't guarantee the absence of PP beetles - it just means it was PP beetle free right after it came out of the kiln.

[Glen Johnson]

Vacuum will also kill the critters. You would have to disassemble your table and make a vacuum bag to fit. The pieces need to lay flat in bag and grooves need to made in the platens to allow air to be extracted. If you go this route, you will end up with a vacuum veneer press.

[Stanley Covington]

Two ways, both work well.

Squirt some gasoline in the holes, then seal them with tape. Yeah yeah, I know the risks: fire, cancer, bad breath. Be careful, do it in a well ventilated area away from your waterheater, and don't let your kids smoke in the vicinity. This method is as old as my grandpa.

Powder a moth ball or urinal cake (put it in a paper bag and crush it with a hammer) and cram the powder into the holes. Cover the holes. The vapors are heavier than air and will penetrate into the deepest parts of the hole so long as up is up and down is down. Takes a bit longer than gas, but works. Only risk is that your wood may smell minty fresh.

The ammonia method sounds interesting. I'll have to give it a try.

[Salem Ganzhorn]

Maybe it is just me but the first one looks like powder post and the second and third look like stray saw marks :).

[Karl Andersson]

Judging from the size of the big holes and the fact that it is dry wood, it is more likely powder post beetle or "old house" beetle larvae. The big round holes mean the adults have already left, the small holes look more like some planing or wear on the benchtop has exposed the "high points" of a larva tunnel - but the larva could still be alive, so a boric acid solution applied in these holes would be worthwhile. You may want to swab the surface of the bench with the solution also - the exiting adults may have mated and laid eggs back on the surface. Doubtful unless you have a lot of the larger holes, but just to be on the safe side, it could penetrate enough to stop newly-hatched larvae.

The ash borers are more of a threat to live ash trees - the restrictions on firewood are to try to slow their migration. The larvae live in the bark and sapwood where it is moist enough for them to live - they shouldn't be a problem in dried heartwood.

There are some State recommendations that suggest using a tight tarp in sunlight to achieve the required 160 degrees for several hours needed to kill the borers. I know I killed a large section of lawn by laying black neoprene pond liner on it in bright sunlight (oops) and the neoprene was too hot to handle - maybe you could get some heavy black plastic from a landscape supplier and move the bench into the sun and wrap it up with an accurate oven termometer; kind of a solar kiln.

By the way folks, don't kill the beatles....they're old and there's only two left...and they've both been knighted...

[Ron Conlon]

Sounds like you got a bug up your ash.

This will only confirm that I have a juvenile sense of humor, but this cracked me up!

[Steve Branam]

You can also do the same with chlorox, but the same precautions apply. A snootful of fumes from a concentrated chlorix solution will be just as damaging as a snootful of ammonia vapors.

And as long as we're talking about these chemicals, absolutely DO NOT mix them. I don't know the precise chemical reactions, but chlorine bleach mixed with ammonia (either plain old household strength or more powerful industrial strength) produces toxic chloramine gas. Bleach mixed with acids releases chlorine gas. You may remember these as some of the gases used in chemical warfare during World War I.

Here's a fact sheet on the dangers of mixing household cleaning chemicals: http://www.state.nj.us/health/eoh/cehsweb/bleach_fs.pdf

[ray hampton]

the ammonia do not had to be full strength, using Clorox water to clean up after pets will form the gas because some pets urine contain ammonia

[Bob Jones]

I closely inspected the whole bench and I only found the holes on a few spots on the top of the bench. I decided to mark the holes that i see and pour a bit of clorox on those spots. I will see if more holes develop. I think it is strange that I only see the holes on the top. I would seem to me that if the lumber were infected there would be holes in more locations. Thanks for the advice!

[Paul Bombardt]

Bob,
You have powder post beetles in your ash. The easiest solution is to coat around the holes and as much of the wood with a product called Boracare. It is a boric acid product used to kill powderpost beetles. Look it up on line, I got mine from a place called Do it yourself pest care. They have loads of info about these critters. They can emerge years after boring and are indeed usually killed by kiln drying, so you may have an infestation that started after the lumber was dried. Other writers are correct, they mostly infest hardwoods, pine seems immune. I have lots of problems with them, mostly in maple and ash and a little in oak. Walnut and cherry seem to resist them more. Polyurethane doesn't seem to stop them. As I understand it, if the hole looks hollow, that is no sawdust in it, that is where they have emerged. If the hole looks like it is filled with powdery sawdust, then they are probably still in the cavity. The eggs are miniscule and I have never seen them. The beetles themselves are only about 1 mm in diameter (the biggest ones) and about 2-3 mm long. I have an old barn that I treated multiple times, and when the beetles emerge, they eat the wood that has been treated, and then die, you'll see them lying around. This goes on for years.

Good luck.

[Scott T Smith]

I closely inspected the whole bench and I only found the holes on a few spots on the top of the bench. I decided to mark the holes that i see and pour a bit of clorox on those spots. I will see if more holes develop. I think it is strange that I only see the holes on the top. I would seem to me that if the lumber were infected there would be holes in more locations. Thanks for the advice!

Those are powder post beetle holes, and you typically find them near the surface of the log. I'll bet that your bench top is "bark side up", which is why the holes are predominantly visible there.

David Keller NC's advice about ammonia fuming is rock solid. I followed his advice to fume a 14" thick, 48" wide oak slab last year, and it worked great. I did fume it for a couple of weeks though, in order to allow the fumes to penetrate as deeply as possible into the wood.

Regarding heating the bench to sterilize it, the comments regarding 160F being required are not correct. You need to heat the core of the bench it to 135F for 4 hours (USDA Forestry Service recommendations). You can do this by building a box out of insulation around the bench, and placing a space heater underneath it. You will want to put a vent in the top so as to control the level of heat. I believe that the December 2010 issue of FWW had some recommendations on sterilizing lumber at home by a similar system.

I have also used the boric acid solutions on large timbers, but only on green lumber. Of all of the methods suggested, IMO the ammonia fuming option will do the least amount of damage to the bench.

All reputable kiln operators run a sterilization cycle at the end of the kiln run - including operators of dehumidification kilns. Either this step was skipped, or the wood became infected after it was kiln dried.

[Bart Nadeau]

I hope Bob will keep us up to date on his bench problem. Also, wonder if he ever discussed with his lumber supplier and what the outcome of that was.

[Matt Uchida]

So using ammonia on a finished piece might mess with the finish? Do you know what types of finish it would mess with or might it mess with all types? I often use a danish oil and top with wipe on poly. I ask because a small end table I made for a relative has some sort of bug in it making a mess.

[Scott T Smith]

So using ammonia on a finished piece might mess with the finish? Do you know what types of finish it would mess with or might it mess with all types? I often use a danish oil and top with wipe on poly. I ask because a small end table I made for a relative has some sort of bug in it making a mess.

Matt, a superior solution to ammonia is to sterilize the lumber with heat. The core of the boards needs to reach 133F for at least 30 minutes. With a small piece such as an end table you can build an open bottomed box out of foil faced foam board, set it and the end table on top of some sawhorses and place a small space heater underneath it.

I have some drawings of this system that were published in FWW magazine a few years back. If you PM me your e-mail address I will be happy to send you a soft copy.

[Kevin Gade]

My understanding is the ash borer live in the bark, not the heartwood. That would eliminate the borer as you problem.

[Matt Uchida]

Matt, a superior solution to ammonia is to sterilize the lumber with heat. The core of the boards needs to reach 133F for at least 30 minutes. With a small piece such as an end table you can build an open bottomed box out of foil faced foam board, set it and the end table on top of some sawhorses and place a small space heater underneath it.

I have some drawings of this system that were published in FWW magazine a few years back. If you PM me your e-mail address I will be happy to send you a soft copy.

Would the heat affect any finishes already applied? I would have to buy a space heater because here in Hawaii we have no use for such things!

[Chris Hachet]

Would the heat affect any finishes already applied? I would have to buy a space heater because here in Hawaii we have no use for such things!

Not sure if it would affect the finish....but heat seems like a simple straight forward answer. I ahve used it in the ast on both antique furniture that has become infested and air dried lumber with good effect. Of course, i also dumped lacquer thinner down any holes and on any infested areas.

[Allan Speers]

This thread is still going? Holy cow.


Just spray some Bora-care on the thing and be done with it. It will soak through most finishes and will kill anything still in there.

[Chris Hachet]

This thread is still going? Holy cow.


Just spray some Bora-care on the thing and be done with it. It will soak through most finishes and will kill anything still in there.

Good to know, as I am looking to build some more stuff with re claimed wood that has been in a barn for awhile.

[Scott T Smith]

Would the heat affect any finishes already applied? I would have to buy a space heater because here in Hawaii we have no use for such things!

Depends upon the finish but I think that most will survive a temp of 140 for a few hours. This is probably a question for Mr. Holmes....

[Steven Woodward]

While sorting through my stack of Ash lumber in preparation for making a bed frame, I notice lots of white powder and lots of dead bugs 1mm x 3 to 4mm. Likely powder post beetles based on earlier comments in this post.

Wondered how I could tell if the bugs and eggs were all dead, or would their destructive activity continue if I built something from this lumber.

After reading all the replies in this post I found solutions to kill the bugs, but no answer to the question of whether the bugs were already dead. Did some googling and found this: https://www.orkincanada.ca/pests/beetles/powderpost-beetles/ " Powderpost beetles require the moisture level of wood to be above 12%."

Checked wood with my Lignomat Pinless Scanner D moisture meter and found the moisture level was below 10%. So I feel safe in using the undamaged portions of wood.

If Bob Jones, the original poster ( from 2006 ! ) is still interested, they could check their bench with a moisture meter.

I purchased the ash a few years ago from a reputable lumber store. Perhaps the moisture content was above 12% so the bugs climbed in from other wood and lived happily until the moisture content dropped below 12%, at which time they crawled out onto the surface and died of thirst (poor things)

[Richard Coers]

While sorting through my stack of Ash lumber in preparation for making a bed frame, I notice lots of white powder and lots of dead bugs 1mm x 3 to 4mm. Likely powder post beetles based on earlier comments in this post.

Wondered how I could tell if the bugs and eggs were all dead, or would their destructive activity continue if I built something from this lumber.

After reading all the replies in this post I found solutions to kill the bugs, but no answer to the question of whether the bugs were already dead. Did some googling and found this: https://www.orkincanada.ca/pests/beetles/powderpost-beetles/ " Powderpost beetles require the moisture level of wood to be above 12%."

Checked wood with my Lignomat Pinless Scanner D moisture meter and found the moisture level was below 10%. So I feel safe in using the undamaged portions of wood.

If Bob Jones, the original poster ( from 2006 ! ) is still interested, they could check their bench with a moisture meter.

I purchased the ash a few years ago from a reputable lumber store. Perhaps the moisture content was above 12% so the bugs climbed in from other wood and lived happily until the moisture content dropped below 12%, at which time they crawled out onto the surface and died of thirst (poor things)
I burnt a couple thousand board feet of ash and soft maple that I had stored in a shed on my Mom's farm. It breaks your heart to through a 2x20x12' on a bonfire. You will be greatly disappointed when you plane that ash. Tiny holes on the surface are no big deal. It's the miles of tunnels inside the wood that ruin it. You aren't out of the woods because your lumber measures 10%. Did you read anything like this? It can take up to 5 years before the larvae will mature into an adult. This means that they maybe feeding on your furniture for up to 5 years! There have been reports of powder post beetlesemerging from furniture 35 years after it was infested!

[steven c newman]

Last load I bought...zero sides of any bugs....may have gotten lucky...

[Scott T Smith]

While sorting through my stack of Ash lumber in preparation for making a bed frame, I notice lots of white powder and lots of dead bugs 1mm x 3 to 4mm. Likely powder post beetles based on earlier comments in this post.

Wondered how I could tell if the bugs and eggs were all dead, or would their destructive activity continue if I built something from this lumber.

After reading all the replies in this post I found solutions to kill the bugs, but no answer to the question of whether the bugs were already dead. Did some googling and found this: https://www.orkincanada.ca/pests/beetles/powderpost-beetles/ " Powderpost beetles require the moisture level of wood to be above 12%."

Checked wood with my Lignomat Pinless Scanner D moisture meter and found the moisture level was below 10%. So I feel safe in using the undamaged portions of wood.

If Bob Jones, the original poster ( from 2006 ! ) is still interested, they could check their bench with a moisture meter.

I purchased the ash a few years ago from a reputable lumber store. Perhaps the moisture content was above 12% so the bugs climbed in from other wood and lived happily until the moisture content dropped below 12%, at which time they crawled out onto the surface and died of thirst (poor things)

There are multiple species of powderpost beetles. The lyctid PPB can survive in lumber dried below 12% and can live in dry lumber for up to 7 years before boring out and laying their eggs.

The small piles of sawdust that you saw (frass ) are typical indicators of an active infestation. The best form of eradication is heat sterilization.