Garden Plot: Non-toxic pest control advice

Silverfish are most often consumers of stored paper, cardboard and books, especially for the glues involved. (De Agostini Picture Library/Getty Images)
Non-toxic solutions for pests

Mike McGrath | November 14, 2014 11:34 pm

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Don’t spray poisons for clothing pests

Steve in Bethesda writes: “In your New Year’s Resolutions column you pledged to help homeowners find non-toxic pest control solutions. I need one for the silverfish in my home. I used to use an exterminator, but we now have two young children, so poisons are out of the question. What are the safe alternatives to keep these pests from eating our clothes?”

Wow, Steve, silverfish are most often consumers of stored paper, cardboard and books, especially for the glues involved. But research confirms that they will eat clothing in a pinch. So to specifically protect your wearables, follow the same rules as with clothes moths:

  • Don’t store clothes with pest-attracting dirt or food strains on them. Always have them cleaned first. Research has shown that many pests are attracted to the stain, then keep eating the cloth (or wool, etc.).
  • Don’t store paper, cardboard boxes, books or rolls of wallpaper (the silverfish’s favorite foods) in closets containing your good clothes. At the very least, don’t let the clothing touch the stored items.
  • Use natural cedar chips in the closet; or even better, panel the walls with thin layers of cedar.
  • Do not use mothballs. They’re nasty little things, especially around children. Unlike cedar, if you can smell the scent of mothballs, you’re ingesting cancer- causing chemicals. They are not safe, and their sale should be banned.
  • Don’t assume that any silverfish sighted in a closet are responsible for clothing damage. Hang a couple of pheromone traps designed for catching the adult form of the clothes moth and see if that’s the real problem.

Controlling silverfish without sprays

Steve in Bethesda wants non-toxic pest control solutions for the other silverfish in his home as well.

Well Steve, as with many pests, silverfish are a sign of a potentially bigger problem: high humidity levels. Silverfish are creatures of extremely excessive moisture, thriving at a relative humidity of 75 percent or above, a level that is also very inviting to a slew of other annoyances, like roaches and millipedes. It’s bad for your home as well.


  • If you’re humidifying your home, stop.
  • If you have any leaks, drips or condensation issues, fix them.
  • When necessary, run dehumidifiers to keep the relative humidity to 50 percent or below.
  • Use moisture absorbing crystals (sold in virtually every home and hardware store) where machines can’t reach.
  • Then use their favorite foods (paper or cardboard, especially with some added paste) as bait. Soak these cellulose-rich treats in a dilute solution of boric acid (harmless to us humans, but fatal to roaches, silverfish and ants) and leave them out where you’ve seen the “fish.” Or try this commercially-available version: Silverfish Paks (Just ignore their “use pesticides first” advice.)
  • Dusting boric acid powder in areas they’ve appeared is also effective against all three pests. Boric acid works against these soft-bodied pests two ways: It dries them out and it slowly poisons them.
  • And don’t kill spiders or house centipedes; they are voracious predators of silverfish and other true pests.

Mouse in the house

Rebecca in Alexandria was also fast to cash in on my New Year’s Resolution to help homeowners find non-toxic pest control solutions, specifically for mice. She writes: “We’ve tried snap traps and glue traps and have caught a few, but still have some left and we’re about to buy D-Con out of desperation, even though it’s a poison and we’ve got two little kids.”

Don’t do it, Beck! Poisoned mice and rats will crawl inside the walls of your home to die, making a terrible stench and attracting many more pests! The poisons are also a great hazard to children and pets: .

To safely and sanely get rid of rodents:

  • Keep trapping!
  • Get new snap traps, wear gloves when setting them to disguise your scent and use peanut butter for bait.
  • I don’t personally like glue traps, but if you want to use them, nail them to small wooden boards to increase their weight and thus their effectiveness.
  • Locate traps inside any cupboards or pantries where damage or scat has been seen.
  • Place “out in the open” traps tight against baseboards. (Mice try and avoid the centers of rooms.)
  • Check out the new “Rat Zapper” and similar traps that use battery power to electrocute vermin. They even have a signal light to let you know when your house is “one mouse less.”

Roaches are not a sign of a dirty home

Rebecca in Alexandria also wants some non-toxic pest control solutions for roaches. She writes: “We hadn’t seen one in months and then one appeared in the bathroom medicine cabinet! Every now and then we see one; never a lot of them.

When this happened in the past we had a pest control company spray indoors, even though that wasn’t our preference, especially with two small kids. Please offer us another solution as I would prefer not to spray.”

And, like most people with such problems, she feels unnecessary guilt over the appearance of pests that are endemic, almost unavoidable and pre-date mankind. “It must sound like we live in a mess, but we try and keep a clean house — although it’s a row house, so we’re not sure what might be going on the other sides of our walls.”

You nailed it, Rebecca. The “Roach Researcher”, which I consulted for this story, pointed out that roach problems are always going to be worst in row homes and apartments. That’s not so much because something terrible is happening in the other units, but because it’s difficult for multiple households to coordinate their extermination efforts. So the pests can generally find a safe haven and then return to your place later. That makes vigilance key.

Oh, and thank you for getting over your fear and asking for advice. There are many other listeners who will benefit from it, who didn’t have the courage to ask.

Controlling roaches without spraying

  • Don’t panic and start spraying toxins around. Indoor spraying has been shown to increase pest problems by killing off spiders and other beneficial predators.
  • Roaches are creatures of moisture, not filth. So fix leaky faucets, drains and roof areas.
  • Dust some boric acid powder around baseboards and under sinks. Harmless to humans, boric acid is deadly to roaches, ants and silverfish.
  • Put sticky traps (like the famous Roach Motel or this easier-to-inspect version) under sinks.
  • Dust baseboards of common walls with boric acid powder.
  • Trap them! Get pint-sized jars and put a little bit of bait in the bottom (water alone is good. Or try fresh paste or a something with protein, like a few pieces of dry cat food). Then smear some Vaseline around the inside lip of the jar to prevent their getting back out again. (Roach Researcher Dr. Joe Kunkel specified that you must use brand-name Vaseline. He says you can’t depend on generic brands for this admittedly “off-label use.”)

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