Keeping carpenter ants out of your home

Remember summer pyjama parties when you were eleven? Remember how the kids used to pile into a tent and tell ghost stories like 'Windigo', and scare the pants off each other? And remember how there was always one kid hiding at the bottom of her sleeping bag with a really loud transistor radio so she couldn't hear the story? And then at the end of the story when everyone screamed, she screamed the loudest and then usually barfed? That was me. I was overly sensitive.

So when I found out that carpenter ants were living inside my walls, and that if I didn't stop them from chewing the framing to bits, I would soon be sleeping in a tent again, I knew I had to have a strategy. I plunged my head under a pillow and tuned my short-wave radio to Helsinki where, as far as I could make out, things were going perfectly well.

After several minutes of upbeat Finnish banter, I felt energized and even cocky. I went back downstairs and looked at the pile of sawdust beside the front door. I watched ants emerge from a tiny hole at the base of the doorjamb, drop wee chunks of my framing onto the porch floor and disappear back into the wall.

As foreshadowed in last week's column, there is one reason why carpenter ants move into houses. That reason is moisture. Carpenter ants don't like chewing dry wood; it's too tough. They like their wood wet or even rotten, the better to sculpt lovely smooth chambers in which to raise ant babies.

How bad can it be? One pest control guy reported treating a place in Muskoka for a colony of 150,000 ants, all chewing like baseball players during a bad inning. He could hear those ants with the naked ear: an insistent, scrabbling sound coming from inside the walls under large (leaky) picture windows. Creepy? I'm in my sleeping bag just writing about it.

How to Know if You've Got 'Em

Carpenter ants come in many castes, sizes and colours, so it's easier to identify them by their location and behaviour rather than appearance. Here are their favourite locations:

• Inside the walls next to poorly caulked doors, windows, bathtubs, showers, sinks or improperly grouted shower pans
• Inside walls or under floors near steady or intermittent plumbing leaks
• In attics near plugged gutters
• In firewood (mostly softwood, i.e. pine or poplar) stored outdoors, near the bottom of the pile where it stays damp
• Anywhere around the outside of your home where soil is in contact with wood

Your primary tip-off is 'frass' - a pile of excavated wood particles mixed with dead insect body parts and ant poop. Live ants in the vicinity of a frass pile means you have an infestation.

What You Can Try

Follow the ants to discover the whereabouts of the nest(s). They're more active at night, so stake out frass piles with a flashlight. Once you find their main entry points you can call a pest control company or try solving the problem yourself.

If you go the DIY route, use boric acid powder (not crystals!) puffed into the holes, cracks and crevices around the nest (use a flexible plastic ketchup dispenser as a puffer). Boric acid is somewhat slower acting (3-10 days) than synthetic pesticides, but it is extremely long lasting. Boric acid was used on the wood in Stradivarius' violins and that's why they're still around today.

What the Pest Control Companies Use

Pest control companies are fast, efficient and guarantee their work. They'll apply a three-inch band of perimeter spray, both outside, along the base of your foundation, and inside at floor level in the affected area. In addition, they'll use a powder that is 99% talc, 1% Bendiocarb, puffing it into the nest in the same way I was describing applying boric acid powder.

Now, Bendiocarb is a neurotoxin that poisons the nervous system of insects and mammals, and can be an irritant to infants, children or anyone with asthma. The New Jersey company that makes it, AgrEvo, has voluntarily stopped manufacturing it at the request of the Environmental Protection Agency, but remaining stocks of Bendiocarb are still in use by pest control services. Many Canadian pest control operators would prefer to use newer, more effective products, but are frustrated by the Canadian government's lag time in registering new pesticides. Paul Terhart of Environmental Pest Control laments, "We're stuck with using long-standing formulations that have been approved for use in Canada when there are great new foam-based products available in the U.S. The foam penetrates tight spaces, is more accurate and you use a lot less pesticide to achieve great results, but Agriculture Canada will have to do its own studies rather than using the U.S. data. So we're all waiting."

The perimeter spray Permethrin is a popular synthetic mimicking the African chrysanthemum resins found in natural pyrethrin. Permethrin is much more stable than natural "chrysanthemum dust", and is effective for 30 days, where natural pyrethrins start breaking down within hours.

On the down side, recent U.S. government and independent studies show that some synthetic pyrethroids can cause reproductive problems, dermal and respiratory allergies, neuro-toxicity, kidney and liver damage, disruption of the endocrine system and enhanced breast cancer risk. So if your pest control company says "safe as chrysanthemum flowers", but they're using a synthetic like Permethrin, they don't have all of the facts. No, Permethrin isn't harmful once the airborne spray has settled, unless you lick it. So perhaps you can live with that. If you want to know more, visit www.beyondpesticides.org. And take your transistor radio.

Talking to Pest Control Services

If you go with a pest control company, request the least toxic application they have. Some companies will give you many reasons not to worry about the health or environmental risks of pesticides, and may convince you that conventional pesticides are more effective than less toxic alternatives. Don't give in. In virtually all cases of pest management, there are excellent prevention measures not associated with the high risk for pesticide poisoning. And if anyone knows of a company that will happily use boric acid instead of harsher chemical agents, I'd love to know about it.

HUGE, OBVIOUS TIP: No moisture, no carpenter ants.
So...

• Reduce moisture in your structure. Repair plumbing, roof and window leaks.
• Grade soil around the building to drain water away from the house, so there is no wood-to-ground contact. Soil should slope down and away from your house at a pitch of one inch per foot.
• Ventilate damp areas (i.e. basements and crawl spaces)
• Be a hero to your home, and don't tempt noble carpenter ants away from the outdoors where they do their job of helping to decompose fallen trees so willingly, and so well.
• Get the bumper sticker: "Save the ants! Use your caulk!"