Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
The research paper on bed bug lures (see the references in the first post) described pitfall traps made from small dishes coated with “fluoropolymer resin” (which is, I think, just some Teflon spray lube) and cat feeding dishes with a layer of talcum powder inside. The general notion is that the bugs can crawl in, but then can’t crawl back out.
You can buy ClimbUp Insect Interceptors for roughly $5 each that fit under furniture legs. They have two concentric moats filled with talcum powder, so that you can tell whether the bed bugs were coming or going. That’s helpful if you don’t know whether the infestation is in the bed or in the room.
You can build much the same thing from common household items for basically zero dollars. Your choice.
I made several different types of powder traps from various food containers. The simplest is just a lid from a raisin canister with a layer of powder:
Powder trap
Scuff up the outside edge with sandpaper, although I think the bugs are pretty good about climbing up obstacles on their own.
You can use these under gas lures or furniture legs:
Powder trap as furniture isolator
Be careful the coaster doesn’t snuggle up to the rim, as shown there, thus allowing the bugs to travel between furniture and floor without visiting Planet Powder. In this case, there’s a tape barrier a foot further out: this is our abandoned-in-place couch.
Here’s what happens when a book louse heaves itself over the outer edge:
Book louse in powder
Not only do they lose traction, they get entirely fouled up in the powder.
This, we think, is one of the few bed bugs from our infestation, caught in a powder trap using a carbon dioxide lure:
Bedbug nymph in powder
This is what the critter looked like after rinsing it off in a generous dollop of denatured alcohol:
Bedbug nymph
In my experience, when you find a bug near the perimeter, it just crawled in over the edge: they do not travel very far after landing on Planet Powder. A bug near the center probably came from the furniture, although we didn’t have that happen.
A stereo zoom microscope makes scanning Planet Powder for intruders much easier. Compared to what you didn’t spend on commercial CO2 lures and powder traps, you can buy a really nice microscope and have change left over. You should gimmick up a camera adapter so you can show off your findings.
I also used a headband magnifier. After a while, you don’t even feel like a dork when you walk around the house wearing one. Trust me on that.
If you arrived here by a search engine while looking for something completely different, note that “Planet Powder” has nothing to do with detergents or music.
In general, you cannot solve a bed bug problem by attracting and trapping bugs: there are simply too many bugs that are breeding ahead of their losses. We had (presumably) brought very few bugs home in our luggage, so every one we trapped was one less bug in the room. In any event, the number of bugs caught in the traps would give some idea of how much trouble we were in.
The bottom line: we trapped one or two bed bug instars and no adults.
Anything labeled for use against bed bugs carries a staggering markup and considerable smoke-and-mirrors marketing, but if you go back to the original sources (see the references in the first post), you’ll find out what actually works, which is quite different from what’s advertised.
The study by Wang, et. al., tested carbon dioxide, heat, and chemical lures. Tested singly: CO2 is pretty good, heat is OK, chemical lures definitely come in last. Basically, I think there are way too many significant figures in their results, but under idealized test conditions in a small arena, they collected about 80% of the bugs after six hours.
One key number: the CO2 flow rate was about 170 ml/min, roughly that produced by an adult human.
Another interesting number:
The visual inspections found ≤23 bed bugs in each apartment and they were considered as low levels of infestations.
CO2 mug and powder trap
Based on that, we decided to build some CO2 traps, which led to those observations. Our version of a dry-ice trap used a huge insulated mug filled with dry ice, perched atop an inverted dog food dish. We deployed two traps like that.
The dog dish has a cloth skirt (so the bed bugs can get traction on the way in) and a layer of talcum powder inside (so they can’t get any traction on the way out). The gas flow rate was in the right ballpark.
After several days, we had collected exactly zero bed bugs.
That wasn’t surprising, of course, because we knew we didn’t have all that many bugs, but we were still getting bitten in other parts of the house. Like, alas, the guest-room bed where we’d moved after gutting our bedroom.
Using dry ice as a CO2 source is relatively expensive and exceedingly inconvenient. We went through two iterations and decided that this was far too expensive, given the expected results.
It turns out that baker’s yeast metabolizes sugar into ethanol and carbon dioxide as the yeast gradually dies in a sea of dilute ethanol; if you have a distillation rig handy, you can probably get a decent yield of vodka from this project. Normally I use the carbon dioxide to stretch bread dough, but in this case it came in handy all by itself.
You can buy, for $50, a Bed Bug Beacon or you can build your own carbon dioxide lure and trap from ordinary household items for pretty close to zero dollars. Your choice.
I built and deployed four yeast reactor lures, built from gallon milk jugs and Tygon tubing from the parts heap. This picture tells you pretty nearly everything you need to know.
Yeast CO2 generator
I used a hollow punch to poke those the neat holes in the lids, but a razor knife will suffice. Seal the opening on the bottle cap with something sticky; nothing adheres well to polyethlyene and Tygon, although the contact cement I got with the dryer rear seal worked well.
Cap detail
Put three quarts / liters of warm water in the jug, add a cup of sugar (lots of sugar = longer production = more gas) and a teaspoon of yeast (lots of yeast = more production = live hard, die young), put on a solid cap, and shake vigorously to mix. Swap in the cap with the tubing and deploy. The recipe is totally non-critical and would make a great science fair project…
The dingus on the other end of the hose is the bottom of a cottage cheese container, artfully sculpted into a shallow dish with four small feet between low arched openings. Basically, it’s a little cover to trap the CO2 in a confined area and let it leak out in relatively concentrated streams. I have no idea if that’s how it works, but it was easy to do and keeps the hose from wandering away.
What they don’t tell you is that the gas production from a small yeast reactor is maybe 5%, tops, of the 150-200 ml/min required to mimic a human: I bubbled the gas into an inverted 60 ml syringe and used a stopwatch. The gas production varies strongly with time; after a week it’s down to essentially zero, so I’d say the “11 day” claims for the BBB’s lifetime are, mmmm, fanciful, at best.
Gas production is proportional to the total number of active yeast. Methinks a cup of sugar in three quarts of water will yield more yeast than a packet of sugar in, what, a pint jar? If you drop fifty bucks on a BBB, make some measurements and let me know, OK?
Maybe they use brewer’s yeast, which is an ethanol-tolerant strain of ordinary baker’s yeast. The end product, after a week, smells strongly of ethanol, so I’m not sure how much difference that would make.
In any event, my opinion is that such a minimal gas flow can attract bugs from only a very limited radius, so the results are far less conclusive than dry ice or pressurized-gas lures. Of course, if you have floors crowded with bed bugs, a few of them will stumble across the lure simply by accident.
Of course, there is one lure that’s absolutely guaranteed to attract bed bugs from across the room: you. I’ll discuss that after covering traps and barriers…
We discovered our first bed bug bites one morning, shortly after we returned from our vacation, which meant at least one bed bug had taken up residence in our bed. That should come as no surprise: why do you think they’re called bed bugs?
For historic reasons, we have an oak California King platform bed with a Select Comfort air-bag mattress in the middle of the room. An oak dresser stands at the head of the bed, with various cords from the power strip screwed underneath the bed. An oak wardrobe stands a few feet away, with closets on either side of the room. Floor-to-ceiling bookshelves line one wall.
A bed bug can find an essentially infinite number of harborages within easy walking distance.
We dismantled the bed:
Everything washable into bags, then to the washer & dryer
Pillows directly to the dryer
Mattress & air bags to the attic
Compressor & wiring to the attic
Wood parts to the driveway, baking in the sun
Foam padding to the driveway, plus an alcohol spray
The woodwork reached a surface temperature of 150°F and, after a few rotations to let the interior parts heat up, got stacked on sawhorses in the garage. Some smaller wooden parts of the bed didn’t collect enough energy to get hot enough, so we sprayed those with alcohol.
We sorted clothing in the dresser & wardrobe & closets into bags, tagged the bags, and moved to the attic. When it’s needed, we first wash and dry it; we’ve been activating the “winter clothing” bags in the last few weeks.
Hint: you must tag the bags as you seal them. The attic is a sea of black plastic trash bags, piled two and three high after their initial heating, and there is no way you can remember what’s inside a particular bag without a label.
The dresser and wardrobe got hauled to the driveway, heated, and stacked in the garage. You must keep rotating the pieces so the desired surface gets sufficiently hot; the driveway resembled a tag sale for several days.
We took bags and suchlike to the attic during the hottest part of the day, to ensure that any bugs couldn’t just walk away without being toasted.
If the weather had been cool and wet, this whole process would not have worked. As it was, we had reasonable confidence that any bugs were either dead or isolated in a bag.
Mary decided this was a good time to give the room a thorough cleaning, so she vacuumed the books and washed the shelves. She also washed the floors and walls, leaving the place immaculate… after which, I poofed diatomaceous earth around the edges of the floor.
Now, how would you go about demonstrating that there were no bed bugs left in that room? Obviously, you’d set out a baited trap and see what it collected.
Although pesticides generally don’t work against bed bugs, the critters seem surprisingly susceptible to overheating, with the Australian CoP (references in the first post) noting:
Bed bugs are very sensitive to heat and are rapidly killed when exposed to temperatures over 45°C.
In the US, the equivalent 113°F seems to be regarded as a three-significant-figure Golden Number; I’ve even seen similar temperatures with a few digits trailing a decimal point.
In round numbers, you want to heat objects to an interior temperature of at least 120°F and hold them there for perhaps an hour to ensure the bed bugs get the message. The CoP observes:
It is often claimed that bed bugs can be killed via heat by placing infested materials into black plastic bags and then into the sun. However, a scientific investigation has shown that this can be ineffective with large items such as mattresses, which have a high thermal inertia
Our infestation began during late July and early August, with clear skies and high temperatures. Our house has an easily accessible attic that becomes unbearably hot on sunny summer days. We have also learned to park the van so the huge windshield isn’t aimed at the afternoon sun.
The attic air temperatures in August were, at best, marginal, according to a data logger tucked into gel packs inside a foam box, with an external sensor dangling in mid-air:
Attic temperatures
While the air temperatures got over 120°F, that didn’t necessarily mean the contents of the canonical black plastic trash bags would heat up. We did put most of our clothing (in bags) and small items in the attic, moving them there at the peak of the temperature curve, simply to get them out of the house. The peak inside-the-bag temperatures, according to the IR thermometer, generally exceeded 120°F, so we felt comfortable leaving the bags up there.
The van became our main killing machine. The same logger produced this record; obviously, location and weather dramatically affect the interior air temperature.
Van Temperatures
Although the air temperature rarely got above 120, the temperature in the inner layers of clothing inside black plastic bags laid on the dashboard & seats under the sun routinely exceeded 130°F, as measured by the IR thermometer.
Our electric clothes dryer reaches 150°F on the High setting, so we began toasting all our clothing in there. The hot water supply simply isn’t hot enough to matter, so we continued to use the washer’s Warm/Cold setting.
We had been considering getting a chest-style freezer to preserve Mary’s garden harvest and this note in the CoP pushed us over the edge:
If the freezer is operating at or around -20°C, then two hours at this temperature will kill all stages.
The American translation is -4°F, which rounds off to zero. A logger tucked into the freezer confirms that the default thermostat setting of 4 should suffice:
Freezer temperatures
A closer look shows a classic bang-bang thermostat in action, with pretty nearly a 50% duty cycle. The period got longer as we filled the freezer with veggies and similar dense materials.
Freezer temperatures – detail
The freezer disinsected items we didn’t want to (or couldn’t) toast: keyboards, mice, trackballs, notebooks, purses-with-contents, and so forth.
Between the attic, the van, and the freezer, we had sufficient weaponry to make some headway. Remember that we had a small infestation, just a few bugs, and were not trying to disinsect the whole house and all our belongings.
Given that diatomaceous earth (DE) is the only useful insecticide-like substance with residual killing effect, the general idea is to turn your floors into killing fields by spreading a thin layer of DE everywhere. In practical terms, that means around the border of the room, under your bed, and anywhere you don’t walk.
J. T. Eaton makes the canonical duster, which is what I used in our house:
Eaton 530RD Insecticidal Duster
They also have a green-painted version, which they deem more suitable for “green” pest control operators; a red duster evidently signifies a powerful chemical at odds with planet-friendly symbolism. The dusters don’t care what’s inside and the powders all look the same, so do what you like.
This is the “improved” #530 version, BTW, with an insulated plastic tip so you don’t kill yourself poking it into electrical boxes. I can detect the faint odor of a lawsuit behind that improvement, can’t you?
The molded strap holding the cap on the end of the tube wants to spring closed, so I added a twist tie loop to keep the cap out of the way. Pop the cap, hold it against the tube, slide the loop to capture the strap. Sheesh.
Were this sort of thing made by, say, Hitachi, it would resemble a large white plastic pregnant guppy containing a microcontroller, a powder dispensing auger, a projected hologram application guide pattern, LCD coverage readout in g/m2, and a data uplink. Oh, and a USB-charged lithium battery. For twenty bucks in Walmart.
You fill the spring-loaded rubber can halfway with DE, jam in the cork, and discover that you have no idea how to use the mumble thing. The Eaton website has some videos (or search Youtube for the obvious keywords), but here’s what the result looks like under our bed:
Diatomaceous Earth under bed
The CoP says
Dose rate is not critical: even low doses of the DED can result in the death of the insect, it just takes longer.
A mumerical value in, oh, g/m2 wouldn’t be helpful, as I have no way to determine what’s coming out of the nozzle, nor how much each puff covers. Evidently, a barely visible dusting will suffice; those sprinkles indicate I probably applied too much.
There’s a fine layer of DE over the entire floor surface under there, so isn’t not as irregular as it might appear. That’s because, regardless of your intent, the duster poots out a huge blast on the first squeeze: the tube is full of powder and there’s nowhere else for it to go. Hold the duster sideways to get what you see above (after the first poot) or upside down for a minimal layer.
If it clogs, there’s a brass rod screwed into the rear of the tube, but that means you’re definitely getting carried away with the thing.
If you do this in a sunlit room, you’ll be astounded at the amount of dust left floating in the air. It’s a good idea to wear a dust respirator, at least an N95 mask, while you’re poofing away. You definitely won’t want to dispense actual toxins like this, either.
I have no way to evaluate the effectiveness of this treatment, except for our anecdotal evidence that the number of bites we sustained dropped after I dusted the living room, the two bedrooms we were using, and the connecting hallway. That could be due to other factors, but we needed all the help we could get.
The Australian Code of Practice (see the Overview) has a useful table that indicates only one pesticide class has any effect on bedbugs: organophosphates.
Only the OPs (diazinon and pirimiphos-methyl) provided 100% mortality within six hours.
Unfortunately, you aren’t getting your hands on Diazinon these days unless you’re a licensed pest control operator. Even then, it’s heavily restricted and, hey, not something you’d want to sprinkle on your favorite chair anyway.
All of the other pesticides are, by and large, totally useless on contemporary pesticide-resistant bedbug strains. This includes all the pyrethrins and permethrins labeled and sold for bedbug control, both online and in big-box retail stores. In the words of the CoP:
In the study, the natural pyrethrins provided no control and the 3rd generation SPs (permethrin) virtually no control.
What’s left is diatomaceous earth (DE), which is essentially silicate glass from diatom shells, crushed to a fine powder.
We had several pounds of DE that Mary had been using for slug control in her gardens and were delighted to find that it worked reasonably well for bed bugs. As the CoP says:
It is especially effective on juvenile bed bug stages […] . The mode of action is not rapid like other insecticides and it may take some days before death ensues.
There are two classes of DE: agricultural and filter. The latter has undergone additional processing after crushing that renders it useless for pest control; perhaps the corners get rounded off. You want ordinary agricultural DE, not pool filter media. You do not need anything fancy; special “DE for Bed Bugs” is (apparently) ordinary DE with a higher price tag.
The general idea is to spread DE on your floor, so that any bed bugs passing through it get a dusting that will dehydrate and eventually kill them. Remember, you must kill every bedbug that bites you, so dusting them on every trip across the floor is a step in the right direction.
Alcohol also works, but only as a direct-contact poison with no residual action (because it evaporates). You can use rubbing alcohol (isopropyl), denatured alcohol (ethanol + methanol), or, if you’re a high roller, just hit ’em with straight vodka (ethanol) shots. An alcohol spray is more suitable for furniture than DE, although it will chew up shellac-based wood finishes, can raise the fibers on the crappy particle board found in most furniture, and may dissolve or distress some plastics.
Both DE and alcohol are cheap and readily available. You need not pay top dollar for special bed bug versions; get ’em in bulk quantities at your local big box home repair retailer (well, not vodka… use denatured alcohol).
None of the other pesticide products you may have seen advertised have any effect, regardless of exorbitant price or enthusiastic anecdotal evidence. It’s that simple. Read the CoP (which does not discuss alcohol) and weep.
Because our infestation consisted of a relatively small number of bed bugs, our primary goal was to prevent any instars from reaching maturity and breeding. The secondary goal was to eliminate any existing adults, one of which seemed to be an egg-laying female.
An ordinary house, ours included, presents an essentially infinite number of harborages suitable for bed bugs. Despite what the references will tell you, it’s impossible to remove / seal / stuff all of the cracks and crevices in which bed bugs may reside between meals. We didn’t make extraordinary efforts along those lines.
On the other hand, here’s a simple truth that I haven’t seen anywhere in the literature: The numbers are on your side! To wit:
You have many opportunities to kill any given bed bug during its progression from egg to adult
Each of the five instar stages must have at least one blood meal before molting to the next stage. If you have only a 50% chance of killing the bug at each feeding, only 3% of the eggs will reach maturity: 0.031 = 0.55. That’s still too many, but if you’re 75% effective at killing the bug that just bit you, you can reduce the odds of having an adult bug to essentially zero: 0.001 = 0.255.
You do that by:
Making your floors inhospitable
Isolating your furniture
Calling down the angelfire every single time you get bitten
Bed bugs may crawl on walls as well as floors, but most of your furniture stands on the floor. Spreading diatomaceous earth along the floor, covering a few inches from the baseboard, ensures that bed bugs will pick up a lethal coating of sharp dust particles. This won’t kill them immediately, but it’s cumulatively quite effective. Best of all, diatomaceous earth isn’t poisonous to you.
With all of your furniture isolated from the floor, using cheap and effective home-brew traps that I’ll discuss later, you know that the bed bug that just bit you is in one of two places:
on the furniture
on you
Sterilize both locations and you’ve most likely killed the bug.
Repeat as needed.
Because bed bugs inject an anesthetic while they withdraw blood, you probably won’t feel a thing during the bite. Indeed, you probably won’t feel an early instar crawl along your skin, even though you’d swear you should. We generally notice the itching sensation shortly after the bite, while we’re still sitting in the same position. If you don’t react to bites, this technique won’t work.
At that point, we stripped down, put all our clothes directly into trash bags without letting them touch the floor, sealed the bags, and took a thorough shower. Bed bugs prefer living in clothing to living on skin, but a smaller instar may not have made the leap and you want to be certain you got rid of it.
You then wash your clothing and run it through the dryer to be certain you killed the bug.
During one particularly trying day, I took four showers. This will be rough on your skin and your clothing, but … consider the alternative.
You must then make a decision: try to disinsect (a new term to us, too!) the furniture or discard it. After reading the process required to kill insects in upholstered furniture, we chose to discard (after acquiring bites while sitting on each item) a pair of rather old Barcaounger recliners, the living room couch (which is currently isolated and abandoned in place, pending a spring pickup), three office chairs, and sundry other bits and pieces.
While we were not certain that those furniture items contained bugs, nuking them from orbit was the only way to be sure the bug wouldn’t grow up and reproduce.
Our living room furniture currently consists of a rocking chair, a footstool, some straight chairs (one serving as a desk chair), three pole lamps, a table, two desks, and very little else. What remains is easily sterilized, offers few harborages, and can be (is!) isolated from the floor.
I told you this would be expensive.
You must be certain you kill the bug that just bit you and we think there’s no other way to make that happen. Spreading the type of insecticide required to kill bed bugs all over your furniture seems neither practical nor desirable. You could bag the furniture up and wait for a year until the bugs die from natural causes, but that’s simply not practical.
Repeat as needed. With any luck, you will run out of bugs before you run out of furniture.
Then there’s what we did to our bedroom. But, first, I must digress into pesticides.
The Smell of Molten Projects in the Morning 