The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Author: Ed

  • Bed Bugs: Killing Fields

    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
    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
    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.

  • Bed Bugs: Pesticides

    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.

  • Bed Bugs: Assured Destruction

    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.

  • Bed Bugs: Infestation and Breeding

    The first thing to understand about our infestation is that we never actually saw an adult bed bug. In fact, of the hundred-odd photos I took during the experience, it’s not clear that any show a bed bug.

    That’s a crucial difference between our infestation and the horror stories you’ll read about elsewhere. Our infestation consisted of a relatively few bed bugs and, because we (generally) acted quickly, decisively, and consistently, they didn’t multiply beyond control.

    There is no mistaking a bed bug bite, however, and that will probably be the first indication that you have an infestation. The references in the first post in this series should give you a general idea of what a bite looks and feels like, but here’s a quick summary:

    • You’ve never felt a bite itch like that in your life
    • Two or three such bites, a few cm apart, are diagnostic

    Some people have a long-delayed reaction or no reaction at all. If you’re one of those folks, then our techniques probably won’t work for you, unless the rest of your family has more “normal” reactions.

    Bed bugs are obligate hematophages: they must have at least one blood meal at each stage of their life cycle. That’s where you come in. While they prefer humans, it seems any mammal will serve in a pinch, and if you’re the sort with indoor dogs or cats, you have a real problem.

    Because they’re only a few millimeters long, bed bugs tend to stay relatively close to their food supply (i.e., you), rather than commute long distances. The bed bugs you brought home will, most likely, quickly take up lodging in your bed, a favorite chair, or the desk where you sit for a few hours. Eliminating all of those lodgings, known as harborages, is essentially impossible, despite what you read in the references.

    Each of the five instars from egg to adult requires at least one blood meal to provide enough energy to grow and molt. An adult female bed bug requires one meal after mating, after which she can produce a few hundred eggs without another meal. Although the references aren’t forthcoming, we think bed bugs have no qualms about introducing loops in their family trees: any male may inseminate any female.

    (Digression: So you think you’re comfortable with weird sexual practices? This will turn your stomach: bed bugs practice traumatic insemination.)

    Our overall plan of battle, then, was quite simple:

    • Eliminate as many harborages as practical
    • Prevent every instar from progressing to the next stage
    • Prevent breeding

    The plan may be simple, but the implementation posed some, ah, difficulties…

  • Bed Bugs: Overview

    Back in July, we returned from our bicycling vacation with a few bed bugs in our luggage. We have our suspicions about where they came from, but that’s not really relevant: bed bugs can come from nearly anywhere. You can bring a bed bug home from a classy hotel just as easily as from a sleazy dive… and you will!

    After three months, we think we’ve eliminated the last bed bug: no bites for the last three weeks. One can never be absolutely certain, but that’s definitely a good sign, particularly in combination with the monitoring measures we’re using.

    We accomplished this on our own, without the use of a licensed PCO (Pest Control Operator) and without the use of toxic chemicals. It was, however, extremely expensive in terms of time, materials, and furnishings, as well as completely disrupting our family life.

    While our methods definitely do not scale to the level required for a major infestation, most likely you’ll be in our situation: you return from a vacation with one or two, um, guests. If you understand what we’ve done and why we’ve done it, you’ll have a better basis for your own decisions and actions.

    So.

    Most of what you’ll find in the usual Internet forums comes from (possibly) well-meaning folks who haven’t done any reading or experimentation: it’s raw anecdotal experience. Not to slander them, but it’s better to start with the basics, which you get from the primary sources.

    To that end, here are the better sources we’ve found and used:

    With those references in hand, I can describe what we did and how it worked. If you’re the sort who can’t drive past a nasty accident without gawking (and we are all that sort, really), then the next week or so should be good for at least that level of amusement…

    A note to the potential purchasers of our house, when you read this in what’s currently our future: yeah, bed bugs. The only difference between this house and the next one on your list is that you know what happened here, what we did, and how it worked out. Trust me on this: no other homeowner will tell you anything about their bed bug experiences, to the extent of lying to your face.

    Believe it.

    Update: Here’s a quick index to the rest of (this chapter of) the Bed Bug Story:

  • LyX and LaTEX Tweakage

    Minor tweaks to the Lyx document settings I used there for the Trinity robot contest rules.

    Controlling line numbering with the lineno package:

    \linenumbers
\nolinenumbers

    A two-column layout with change bars seems to stretch the machinery to the limit; the varioref package (sucked in automagically by something else) often complains (quite properly) about changed blocks spanning boundaries that might cause an infinite loop. Save the file, then turn the error message into a non-fatal warning to see what actually happens. Turn it back into a fatal error when done:

    \vrefwarning
\vrefshowerrors

    It seems impossible to alter change bar colors from the default blue and red in PDF documents, so I tweaked the PDF link colors instead. Use the xcolors package in place of colors, then pick a different color from the Base Colors set (to avoid having to figure out how to specify another set) in the Additional options part of the PDF Properties tab:

    urlcolor=teal,linkcolor=teal

    In principle, changing the \dvipost options should work, but not with PDFs created through pdflatex. For example, this has no effect:

    \dvipost{cbstart color push Magenta}
\dvipost{cbend color pop}

    Saving a file under a new name with File → Save As completely confuses a subsequent HTML conversion; the .html file loses all the internal formatting and becomes one giant line of text. Save the .lyx file with the new name, close Lyx, start it up again, reload the file, and it’s all good.

    Memo to Self: Convert \vrefwarning back to \vrefshowerrors before it bites you!

  • What Do Squirrels Do When It Rains?

    Rain-soaked squirrel
    Rain-soaked squirrel

    Although I’m not a big fan of tree rats squirrels, I’ll admit this one was having a tough time of it during a recent rainstorm. He (she?) sat motionless on that stub of a branch for well over half an hour, no doubt thinking gloomy thoughts.

    Taken through two layers of mid-1950s window glass, so it’s not the sharpest image in my collection, but I’m not going out in the rain just to take a picture of a squirrel!