Natural Pest Control

Air Date: Week of July 17, 1998

(Music up and under)

CURWOOD: This is Living on Earth. I'm Steve Curwood. Michael Weishan is Living on Earth's garden expert; therefore, our visits with him usually take place, well, in his garden or the greenhouse, or somewhere in the yard. But we're not starting there today. Nope. We're inside his office right now, because we're going to talk about a way that garden plants can help you control bugs inside your home. Michael, how are you today?

WEISHAN: Just fine, Steve, thanks.

CURWOOD: Now, if you had an army of ants marching across your floor right now, what would you do?

WEISHAN: Well, actually, I did. Every spring we have a problem with ants here in this cabinet, and I just tie a few sprigs of tansy together (opens drawer) and lay them right here on the shelf, which is where they have a tendency to congregate. Tansy used to be commonly found in the garden. It's what was once called a strewing herb. It was tossed on the floor so that when people walked on it, it would release its fragrance. But coincidentally, it happens to have an insect repellent quality. Here, just crush a little and you can see it has a rather strong --

CURWOOD: Whoo!

WEISHAN: Yeah. Yeah, the strong scent. You can also, if you have a major problem over a large area, you can take a handful of tansy. And of course that's what the old recipes say; exactly what a handful is I'm not quite sure. But, you know, a goodly portion, a couple of cups, and boil it in a quart of water. Use the diluted spray to spray on floor areas where ants are a problem, and you'll find that it really does repel.

CURWOOD: It's pretty easy to grow tansy?

WEISHAN: It's almost invasive as a matter of fact (Laughs).

CURWOOD: (Laughs) Okay.

WEISHAN: So, one of the problems with growing tansy is that you have a lot of tansy once you start it. But it's a wonderful plant to have in the garden. It blooms in the late summer, very tall, about 4 feet high, with yellow blossoms. So it's a pleasant addition to the perennial border as well as being very useful inside.

CURWOOD: What else do you have in your garden that fights insects?

WEISHAN: Actually we have quite a number of things. So let's take a step outside and we'll go look and see.

(Door opens to bird song; footfalls)

WEISHAN: Here we are out in the garden. The first thing I want to show you is actually one of my favorite herbs, which is pennyroyal. Which is a member of the mint family. You can smell some of that. It's very strong, minty.

CURWOOD: Minty with a funny kind of pine edge to it, almost.

WEISHAN: It smells sort of like Murphy's Oil Soap in a way, if you know what that smells like, yeah. As a matter of fact, it's used in floor preparations and natural mixtures and things as a cleaner. But it also seems to be a terrific repellent for fleas in the house.

CURWOOD: Ooh.

WEISHAN: We've actually used it on the dogs and it works pretty well. Once again, you take a handful of pennyroyal. Now this is a low-growing plant that looks somewhat like mint, it's about 6 inches high, so a handful requires a fairly large clump of it. And once again, you throw it in a quart of boiling water for about 20 minutes. Then when it's cooled you can add that water to the pet's bath and it is a natural flea repellent. It seems to do an amazingly good job.

CURWOOD: Okay, Michael; now what other parts of the house can we protect with plants or herbs?

WEISHAN: Well, in the high summer, one of the best things to think aboutis protecting your woolens in the closet. One of the nice things you can do is make herbal satchels with dried herbs, and there is a number that are very effective against moths. One is this one, southernwood. I'll let you smell a little of that.

CURWOOD: Ooh! Almost, almost like a rose with vinegar in it or something.

WEISHAN: Yeah. It's a pleasant scent, but once again it's strong. And they generally mix this with lavender artemisia, which is a member of the Dusty Miller family; most of our listeners will recognize Dusty Miller. And this southernwood. Sometimes pennyroyal and tansy can all be mixed together by just taking a few sprigs and putting them in an old pair of nylons, for instance, and then hanging them in the closet. It actually works rather effectively for a moth repellent.

CURWOOD: There's a woman I know who insists that putting a little tray of beer outside will kill the slugs in her gardens.

WEISHAN: Ah, well (laughs) that's actually true to an extent. We had a question from one of the listeners through the web site about just that. The problem is that what most people do is put down a tray and then wake up the next morning and find they have a tray full of slugs, and it's not very pleasant. What you're supposed to do is actually take a can of beer, open it up, and increase the opening to about half of the can opener, and bury it so that the level is flush with the soil. It's not that the slugs are poisoned by beer, it's that they fall in the can and drown. They're attracted by it and then they meet their demise drowned in beer. Which I suppose there are worse ways to go, right?

CURWOOD: (Laughs) Now does it matter if you use stout, or is a light lager okay?

WEISHAN: I would suggest anything cheap because you know, you're feeding the slugs here. Granted it is their last meal.

CURWOOD: Michael, we've been talking about plants that you can use to chase bugs out of your house. What about plants that chase bugs out of the garden?

WEISHAN: Yeah, there are quite a number as a matter of fact. Here in the herb garden we plant quite a number of different type of marigolds. And what they work against is a small, invasive insect in the soil called nematodes, which are tiny little worms essentially that eat the roots of plants. Now, for a complete eradication of nematodes you actually have to plant the entire surface in marigolds. But for a minor infestation, scattering marigolds in and around the plants that you're growing works tremendously well.

CURWOOD: Has science done the research here to show that beer and tansy and all these things work? Or is this just from the folk literature?

WEISHAN: Well, it all has a basis in folk literature, because that's how western society became knowledgeable of these things. These things have been passed down for generations, millennia practically. But a lot of it does work. For instance, I happen to know that tansy works with ants. I do happen to know that the pennyroyal does work for the fleas. Are they as effective as getting out your can of Raid? Probably not, but it's a lot easier on you and on the environment.

CURWOOD: Well, I want to thank you for taking this time with us today.

WEISHAN: My pleasure.

CURWOOD: Michael Weishan is Living on Earth's traditional gardener, and he's publisher of Traditional Gardening. Got a question for Michael, just dial up our web site. It's www.livingonearth.org.