Here's how to keep ants out of your plants—and pantry!
Question. Hi Mike: Ants are just about ruining my lawn and garden with their mounds of sand. I can barely dig a hole for a new plant without digging into a nest. So far, I have been using boiling water, but this could take me forever -and I'm not that young! Is there anything else you can suggest?Thanks for your help.
- ---Judyin Central New Jersey
I have ants on my kitchen counter; there is no food on the counter and all of the food is in containers or sealed. They seem to be coming in under the window above the sink. Please let me know of any way to get them under control.
- ----Wanda in Delta, Pennsylvania (right on the Mason-Dixon line)
Mike: My mother's Central California backyard is filled with ants underneath the soil. Is there a home remedy she can make instead of using store bought chemicals?
- ---Desperate in Lompoc, CA
Hi Mike: I love your show; it's full of neat ideas and facts! An old man once told me that Tansy leaves, placed on windowsills and under doors, would repel ants. He gave me some, and it worked like a charm! I think he said it's a moth repellant too!
- ---Jan in Haverford, PA
Answer. Yes, all God's Chillin' got ant problems—because all God's Chillin' got ants! Some disagree able researchers give the nod to termites, but most sources say that ants are the most abundant species on the planet, with an estimated quadrillion—that's the number one followed by 16 zeroes—crawling around at any one time, half of them in your kitchen.
There is good reason to believe that the flowering herb tansy does repel them. Tansy (proper name Tanacetum vulgare) is a member of the famed Pyrethum family, first cousin to one of the original botanicalinsecticides—the "Dalmatian Pellitory" or Pryethum Daisy (Tanacetumcinerariifolium; aka Chrysanthemum cinerariifolium; aka Pryethumcinerariifolium) whose dried and powdered flower heads have been used to kill insects for centuries. Tansy's ability to ward off ants (and flies) is well-noted in the literature, and researchers have used tansy extracts to deter nasty Colorado potato beetles.
The plant itself is also one of the finest natural attractors of beneficial insects, including ladybugs, microscopic predatory wasps, lacewings, and one of my favorite named pest insect eaters—the insidious flower bug. But it is also a large invasive perennial that needs to be contained; take it for granted and you will be growing nothing BUT tansy!
But if you do keep it under control, one tansy plant will produce a huge number of highly aromatic leaves for you. A lot more than the often-touted ant-repelling bay laurel, and from a plant that's a lot easier to care for. Other members of the tansy family, like fever few(Tanacetum parthenium; aka Chrysanthemum parthemium) and the camphor plant (Tanacetum balsamita; aka Chrysanthemum balsamita) might also work well.
Our good friends at the BIRC in Berkeley California, specialists in non-toxic pest control (www.birc.org), have a number of neat tricks forgetting rid of ants. If a line of them is invading your kitchen, wipe them up with a soapy sponge from the furthest one out, following them back to where they're entering—the soap removes the chemical trail they've laid down for other ants to follow. Then seal the crack where they came in. If it's an area that can't be sealed, spray some boric acid dust—often available as 'roach powder'—into the area. The boric acid will kill some ants directly by drying them out, and others when they later groom themselves. And if you get lucky, some will make it back to the nest alive, where the boric acid may be able to wipe out the colony.
Outdoors, flooding often works to rid an area of ants, but boiling water isn't necessary; just keep flooding their mounds on a regular basis and they should eventually move to the outskirts of the property.
But the best solution is to put out baited Traps that contain a low dose of boric acid. The ants take the bait back to the nest, where the slow acting poison—very toxic to some insects, almost non-toxic to us mammals—can kill the entire colony. Here's a detailed description of a pet-safe, ant-deadly trap design from the BIRC:
- Mix together: 3 cups water; 1 cup sugar; and four teaspoons of boric acid. DO NOT USE MORE BORIC ACID THAN THIS! A higher dose would kill the ants immediately; and you need them to live long enough to get the bait back to the main colony. If you see a lot of dead ants around your traps, you used too much!
- Get six jars with tight fitting screw-cap lids;punch some holes in the lids with a Phillips head screwdriver. Loosely pack the jars about half full with cotton balls or batting, then saturate the cotton with your boric acid sugar water.
- Screw the lids on tight and draw 'skull and crossbones' on the jar, just to be safe.
- Leave the jars out where you see ants (d'uh!). Most importantly, do NOT kill any ants from here on in—you have to let them travel to and from the jars safely so they can take the bait back to the colony.
- Not all ants are sugar-suckers; some species prefer protein. If your ants aren't attracted to the sugary bait, make a new batch using cat or dog food. If you have carpenter ants, use wet,rotting wood. Experiment with the boric acid levels until you get the dose right.
- Oh, and if the ants aren't doing any damage, consider just leaving them alone. Ants in the house can be VERY beneficial, preying on flea larvae, silverfish and clothes moths. Outdoors, they fight a much more important foe—termites, their natural enemies. A yard full of anthills is a very effective barrier to termite invasion. (Talk about 'turf wars'!)
You Bet Your Garden Question of the Week ©2005Mike McGrath