Find an elsewhere to be, roaches.
May 30, 2010 5:26 PM   Subscribe

Urban dwellers with concrete yards: Have you had any success repelling cockroaches? I'd prefer less creepy-crawly company in the summer when I'm relaxing in my garden, thanks.

I live in a South Philly rowhouse; I have the typical concrete-walled backyard. The walls are about eight feet high on two sides and about five feet high on the other side. The "oriental roaches" which proliferate in our storm drains and sewers loooove to visit my yard at night. Their telltale silhouettes start appearing on the top of the walls, and soon, they're bravely exploring the patio. Creep, creep, creep. Ew.

Most roach-control products are focused on trapping or poisoning to control indoor infestations. This is not so helpful -- I'm not going to make a significant dent in the waterbug population no matter what, so focusing on killing them seems misguided. I do that by stomping on them.

I'd like to apply something to the tops of the concrete walls that will have a residual effect, outdoors, exposed to the elements. I'd prefer less toxic solutions, but I'm willing to compromise on that point.
posted by desuetude to Home & Garden (8 answers total)
 
You could probably put diatomaceous earth out there, but not sure how long it'd last outdoors.
posted by Threeway Handshake at 5:39 PM on May 30, 2010


Boric acid, mixed with sugar or not. It's easiest if you put it in a squeeze bottle (like a $1 ketchup/mustard bottle) and use that to draw a line along the top of the wall, down in the crevices at the bottom perimeter, and for good measure along your doorways and windowsills. You'll have to re-do it pretty often as it blows/washes away (there are recipes on the internet for a boric acid paste you can make, which might be more durable).
posted by Lyn Never at 5:54 PM on May 30, 2010


Response by poster: Yeah, I know about diatomaceous earth and boric acid, but while both kill roaches, neither repels them.

They're clever and wily little buggers as it is -- I'm not sure I'd want them also smart enough to recognize sundry powdery compounds.
posted by desuetude at 8:38 PM on May 30, 2010


Cats.
posted by johnnybeggs at 9:40 PM on May 30, 2010


My landlord uses pyrethrum powder around the perimeter of our house and patio. Some thing like this. It does keep the insects out. The entire perimeter, except for some doorways is surrounded by a little trail of the powder. There is a service that comes once a month and refreshes the powder. I live in Hawaii, where roaches are a constant companion, this stuff is amazing. It could work in your concrete backyard. I also have 8 cats, and they are not bothered by it, and it helps keep fleas down too.
posted by fifilaru at 9:45 PM on May 30, 2010


I'd try pyrethrum powder too; it's an all-around insect repellent.

And a word about cats... I've never had a cat who ate roaches, nor would I want one to. Roaches are disgusting to we humans for good reason: they run around in sewage and track ickies everywhere. ("They can also passively transport microbes on their body surfaces including those that are potentially dangerous to humans, particularly in environments such as hospitals" - Wikipedia. That wiki article also has prevention ideas.) Plus, many people put out insecticide against roaches, and if a roach doesn't die from it, they carry that around too. It would not be healthy for a cat to eat a sewage-and-insecticide-carrying bug.
posted by fraula at 4:20 AM on May 31, 2010


Response by poster: We can't have a cat due to my SO's allergies. So, that's out. (And they're not necessarily a good roach predator anyway. My former cat would play with them without killing them.)
posted by desuetude at 11:42 AM on May 31, 2010


I live in Houston, Texas. Arguably the roach capital of the Western Hemisphere. I have never held out hope of totally repelling roaches because, pound for pound, they are one of God's most badass creatures and do not scare easily or for long. But we keep them at bay with the following:

1. Roach powder with equal parts boric acid, corn starch, and powdered sugar. Strap an 1/8 tsp measure onto a long stick and use it to put zillions of little deposits in cracks, crevices and crawly spaces.
2. Never kill the things in your yard that kill bugs. My kids know not to mess with the spiders and the various slinky lizards, garden snakes, and newts. We loves our little slinky and spidery friends.
3. I never use diatomaceous earth because it kills rather indescriminately, violating rule #2.
4. Keep a flyswatter handy. Last resort is to use brute strength and the element of surprise. The little buggers will respect your space or at least go to a space that is easier to roam without threat of bodily harms.
posted by cross_impact at 6:27 AM on June 1, 2010


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