Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
So there you have it: the bugs that killed three months.
We’ve gone a month without a bite and are only now restoring furniture to the bedroom. Each piece goes up on powder traps and gets a week in isolation to reveal any bugs before we reload the drawers with clean clothing. After vacuuming and washing there shouldn’t be any bugs left on the furniture, if the piece had any to begin with. Almost certainly that is wasted effort, but …
Maybe next year we’ll buy new chairs and a couch for the living room. For sure, they won’t have plush, overstuffed upholstry.
With any luck (and the regular use of a hot box disinsector), you won’t go through what we did.
However, should you discover a row of bites across your body, the actions you take during the next few days will determine the level of catastrophe during your next year. The problem will not go away by ignoring it; if you get a breeding population going in your house / apartment / condo, you will definitely need a commercial pest-control service.
If you think tossing out some furniture to get rid of a few bugs is expensive: just wait.
Now, having seen what we’ve been living through, you might ask yourself
Wouldn’t It Be Nice If there was some way to be absolutely sure that mumble does not happen to me?
There isn’t, but you can stack the odds in your favor by disinsecting everything that enters your house. In particular, when you return from a trip, you must treat your luggage with the same casual regard as you apply to any lump of highly radioactive waste.
Because all bed bug stages die when exposed to temperatures over 45°C (113°F, which I round to 120°F), the simplest way to ensure that you’re not bringing any passengers home is to heat your luggage / packages / clothing / whatever to an internal temperature around 120°F, then let it soak for maybe an hour to ensure all the occupants get the message.
What you need is a box that gets hot on the inside, but not hot enough to set your luggage on fire. As with all things sold for bed bug problems, the commercial solution seems grossly overpriced for what looks like an uninsulated ripstop nylon bag containing a rack, a heater, and a fan.
It should come as no surprise that I built something that’s bigger, uglier, and harder to use… but it produces data and you can do science. And, with liberal use of my parts heap, the overall price is maybe 10 dB down from the commercial version…
Hot box exterior
I figured that this widget is going to be a major part of our lives from now on, so a foldable / storable heater wasn’t particularly useful. In point of fact, we’ve been using it heavily and I don’t expect that to stop any time soon.
Inside, I used lengths of wire shelving to support the thing-to-be-baked. After we’ve used it a bit more, I’ll conjure up permanent supports for the second level shelving (stacked on the right of the exterior picture); right now, they’re supported on wood blocks as needed.
Hot box interiorHot Box – Dimension sketch
The interior dimensions work out to 34x22x24 inches: it’s made from a single 4×8 foot sheet of insulating board. Here’s my working sketch showing how the parts lay out and fit together. (clicky the pic for more dots).
The only waste is the 1-inch strip along the right edge; the slab I bought came with a molding imperfection, so discarding that edge was OK.
I cut the sheet into four 2×4 foot strips, cut a 13-inch strip off each plank, then trimmed the 1 inch waste. That seemed less prone to catastrophic blundering than (trying to) make a pair of 8-foot cuts and whack each resulting strip in quarters. An ordinary razor utility knife worked fine, although I found that making two passes along each cut produced cleaner results than trying to do it all in one.
I assembled it with the heavy / shiny aluminum foil side inward, although I doubt it makes any difference. Cover all the edges with tape, tape all the joints both inside and outside, and it becomes a nice rigid box when you’re done. Pay attention to getting the sides at right angles; I used a framing square.
The board allegedly has an insulating mojo of:
R = 6.5 ft2 • h • °F/Btu
Figuring a surface area of 32 ft2 and a temperature differential of 120 – 60 = 60°F, the box should require 295 BTU/hr = 87 W to maintain that temperature.
Which, as it turns out, is pretty close to how it worked out:
Hot Box – Temp vs Time – First light
The lower curve shows a 60 W bulb with a 10 W 120 VAC fan heats the interior to a bit over 100°F in 100 minutes, where it looks to be stabilizing. That was the first test and showed that I was on the right track.
The second test, with a pair of 60 W bulbs and the fan produced the two upper curves: one for air, the other inside some cloth jammed inside a plastic bucket to simulate a (tiny) suitcase. The combined 130 W heats the box over 150°F in two hours, with the somewhat insulated bucket trailing neatly behind as you’d expect.
Without opening the box, I connected the bulbs and fan to a Variac plugged into my Kill-A-Watt meter and dialed it for 100 W total dissipation. The temperature fell to slightly over 130°F in 80 minutes and looks like it would stabilize near there.
Ambient temperature was 67°F, so
R = 32 ft2 • 67°F / (341 BTU/hr) = 6.3
Close enough, I’d say. Given those few data points, it looks like the temperature sensitivity around 130°F is 0.7°F / W. [Update: typo in the equation. Doesn’t change the answer much at all.]
I swapped in a 100 W bulb, removed the Variac, and heated the cushions from my office chair.
Hot Box – Chair cushions
One thermocouple is hanging in mid-air, the other is wedged inside one of the cushions. After nearly 5 hours the cushion is up to killing temperature and I turned the heater off. The air temperature drops rapidly, but the cushion stays over 120°F for another two hours.
The light bulb is just a proof of concept, because it’s entirely too hot: if the fan fails, your luggage ignites. I plan to build a rather subdued heater with a surface temperature around 140°F and a controller that monitors several sensors to ensure the contents reach killing temperatures and stay there long enough.
But that’s a project for another day…
[Update: If you’re arriving from a link, start at the overview to get The Whole Story.]
Even half an inch of masking tape forms an impenetrable barrier for small creatures; you could splurge on 2-inch tape to get more surface area if you’re squeamish. I did see a spider stepping daintily along a barrier, but, for the most part, all these specimens became mired within a few millimeters of an edge. That made it easy to decide which direction they were traveling: incoming insects stuck near the floor and a (very few) outbound insects stuck at the top, just after leaving the non-sticky surface.
This is, we think, a well-fed first- or second-instar bed bug caught on a tape barrier; it’s not quite the right shape for the book louse seen below. A powder trap caught the only other bed bug in our collection.
Bed bug on tape
In addition to that sole bed bug, the tape barriers captured a steady stream of critters that were not bed bugs. The trick is sorting through all the false positives…
Given the number of books in the house, we caught many book lice. These have a disturbing resemblance to bed bugs, but are basically harmless to humans. You don’t really need books to have book lice, although we captured most of them adjacent to our bookshelves.
Book louse with 0.5 mm scale
This scary critter is a carpet beetle larva. They survive on any fabric surface and can infest upholstery as well as carpets.
Carpet beetle larva with 0.5 mm scale
Dust mites, at least for their first few instars, are transparent little bags of bug stuff. The first instar may have six legs, just like a first instar bed bug, but successive instars have eight.
Dust mite first instar
Here’s a close up view, showing it has eight legs:
Dust mite
We have no idea what this cute little thing might be. It’s about 0.5 mm in diameter and, to the naked eye, looks like nothing so much as bed bug crap. But it’s alive!
Spherical insect – dorsal
This terrifying apparition sprinted across the (non-isolated) kitchen table, whereupon I mashed it with a magazine. It’s most likely not a bed bug; we’re guessing a spider of some sort. That stylet in its proboscis doesn’t look spider-ish, though.
Red insect with stylet
It might be related to this eight-legged critter; the lancet on the front end is similarly scary. The legs aren’t the same, though.
Mystery bug
All in all, we found a bewildering variety of insects, bugs, and spiders wandering around in our house. None of them are particularly harmful, although I now have a (most likely pyschosomatic) allergy to dust mites.
We’re not entomologists: if you know what the mystery critters are, I’d like to hear from you!
Up next: a Hot Box that might forestall all this excitement.
During the course of our adventure, we disinsected four rooms with varying degrees of attention to detail.
Our bedroom: everything except bookshelves
Guest bedroom: killed bed, but not much else
Living room: killed desks and chairs, isolated couch
Downstairs office: killed desk and chairs, spread DE
In each case, we wondered how could we demonstrate that there are no bugs left to kill? Yeast reactor lures don’t produce human-scale amounts of carbon dioxide, although we did deploy them to see what happens. Simply moving everything back into the room didn’t seem like a Good Idea: repeating the whole process if we got another bite wasn’t attractive.
Given the low level of infestation, we decided that the most effective bed bug lure was an actual human: me. Ideally, we could intercept the approaching bed bugs before they bit me and, if no bed bugs were attracted to me, then we simply didn’t have any.
Now, I’m not sufficiently brave (or stupid) to simply spend the night (“sleeping” may be too strong a term) on the floor, waiting for a bed bug to stroll over and puncture me. I laid out a barrier around an air mattress and sleeping bag: a ring of masking tape folded so half stuck to the floor and half presented a sticky surface to incoming bugs.
Tape barrier on floor
To date, we’ve gone through four rolls of masking tape and I just bought two more three-packs. Buy in bulk and save!
The best tape is ordinary, albeit good-quality (we’ve been using 3M), painter’s masking tape; the three-day kind works fine. Fancy long-duration blue tape isn’t sticky enough. You should pull the tape up, examine it for stuck bugs, and lay down fresh tape about twice a week.
This works well on our hardwood floors, but wall-to-wall carpets probably won’t provide enough flat surface for the tape. If you’re serious about this project, those carpets might just have to go…
I’ll leave to your imagination the picture of an air mattress, sleeping bag, and suchlike in the middle of a large rectangle of tape inside a stripped room. I’ve been sleeping that way, in various rooms, for the last three months. I didn’t spend any nights in the basement: it’s just too cold down there, even in summertime.
We only recently reassembled our platform bed, with a layer of diatomaceous earth underneath. I taped the cracks and gaps around the platform and applied a ring of tape to the outside: any intruders will encounter a sticky surface. So far, no bugs, although I just renewed the tape once again.
Isolated platform bed
You can also lay tape down with the adhesive facing inward. Here’s the living-room couch we’ve abandoned in place, up on powder traps and isolated with a ring of masking tape:
Isolated couch
After you’ve deployed a variety of lures, traps, and tapes, you’ll start collecting a wide variety of insects and bugs. Some of them might even be bed bugs…
[Update: If you’re arriving from that link in bedbugger.com, this adventure has many parts. Start there to see them all.]
After we dismantled our bedroom, Mary got bitten while sleeping in the guest bed. That bed, a much smaller, more-or-less standard double bed mattress and box spring on a metal frame, was much easier to disinsect:
Wash and dry all the bed linens
Toast the pillow in the clothes dryer
Vacuum the mattress and box spring
Encase the mattress and box spring
Heat the frame to killing temperature
Reassemble everything
Encased mattress and isolated foot
However, there’s not much point in doing that if a bed bug can simply crawl from the floor up a bed frame leg. We put powder traps under each bed foot, using tall containers to prevent access.
Although the traps collected a fair amount of dust, we didn’t find any insects of any kind in the powder.
Yes, that’s a length of Kapton tape on the mattress encasement. Mary discovered that heating the encasement with a hair dryer isn’t a good idea: the fabric is actually a non-woven plastic film that melts at a surprisingly low temperature. Kapton sticks to the fabric and the adhesive doesn’t promptly turn into goo.
Powder traps work well for stationary furniture like beds and tables and desks, but they aren’t useful for chairs. I applied a ring of tape (masking or duct, as you prefer) around chair legs, folded lengthwise so the sticky side is outward. The tubular steel legs on this office chair terminate in fishmouth welds on the central pillar, so the bugs can’t crawl up through the inside:
Isolated desk chair
That’s the chair I pulled out of storage after scrapping out my homebrew car-seat chair. Turns out I installed the replacement seat about a week before sustaining a bite while sitting at my desk. Calling down the angelfire on that comfy chair was more annoying than expensive, but … no more bug bites in the basement!
For historic reasons, I use an ancient Balans chair at the Electronics Workbench. Four strips of masking tape isolated it from the floor:
Isolation tape on Balans chair leg
Isolating the chair from the floor obviously doesn’t prevent a bed bug from crawling up your leg, but we never had a problem with that. They’re not really hunters and vastly prefer to lurk in furniture than track and pounce on a moving shoe…
As it turned out, we never trapped any bed bugs on chair legs, which is most likely a testament to how few bugs we actually had. However, larger tape barriers were quite effective in another context: isolating entire regions of a room.
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…
The Smell of Molten Projects in the Morning 