When I’m not traveling I sleep in a barn that’s been renovated a bit for people. I moved out there in May when I still needed a hat and sleeping bag. This week it’s gotten a bit chilly again. I think I need to break out the blanket.
Despite the chillier evenings and dog day cicadas buzzing in the trees, I refuse to admit summer is winding down. I’m a believer in timing seasons according to the equinox and solstice, which means we’ve got until September 22nd to BBQ.
In this blog I try to post on topics that are relevant for the time of year. Many pests have seasons, even in parts of the country where the weather doesn’t vary too much. One of the pests that I meant to post about this spring was the carpenter ant.
Each year, usually in the spring, mature carpenter ant colonies will send out winged swarmers to look for new places to colonize. That's when I usually get inquiries. But this year people have been coming to me all summer. It’s time I put all my thoughts and recommendations in one place. Perhaps this will be relevant for some of you now. If not, file it away and dig it out next spring!
What really triggered this post-season-post was an amazing video sent to me by some friends at the end of June. They were hearing things in their ceiling and were psyching themselves up to open up the void and have a bear jump down on them. When they sent me this video I knew with almost certainty what they were dealing with—carpenter ants. http://youtu.be/v5BvCzXR07g I love playing structural CSI!
One or more of the following signs can clue property managers, maintenance staff, or residents in to their carpenter ants:
- A crackling noise in the wall (see the youtube video!)
- Piles of sawdust, often with ant body parts in them (carpenter ants don’t eat the wood, they excavate it.)
- Winged ants either crowding a window or crawling around.
- Ants without wings crawling around in areas where there is food or moisture.
Common places to find carpenter ant colonies are wall voids, insulation, hollow doors, window sills, and around plumbing in kitchens and bathrooms. Wherever there’s moisture. Outdoors they may be in anything wooden.
Think you might have carpenter ants?
Here’s what to do:
1. Inspect and identify
Inspect in the evening or at night when carpenter ants are most active. Don’t just look inside, walk around outside too—you’re looking for a trail of ants. If you don’t want to stay up or go onto your property at night, have a PMP place sticky trap monitors in kitchens and bathrooms and anywhere else you might suspect them. The PMP or person placing the traps has to think like the ants and place the traps where the ants will run over them.
Most people can picture an ant. Carpenter ant adults are often large (1/2”), but some species are small (1/4”). Colors can vary from black to red depending on species. There are many species across the U.S. Send a sample to your nearest diagnostic lab (usually university-based) or have a PMP take a look. Proper identification is key—you want to know whether your ants are destroying wood.
If you do find a pile of sawdust, look up. You may see a small slit or hole where the ants are pushing out their fallen comrades and waste from their construction project.
Around this hole, or wherever you are hearing crackling, tap on the wall with the handle of a screwdriver and see if it sounds hollow. Caution: if the wall is so thin that the handle goes through you may end up with ants pouring out of the wall. Have a vacuum ready. (See last week's post for how to use a vacuum for pest control: http://stoppests.typepad.com/ipminmultifamilyhousing/2011/07/vacuums-very-accessible-control-sample-newsletter-article.html)
Another cool tool is an infrared thermometer. If you have one of those sitting around, scan the wall and see if there are hot spots—a colony of ants will generate some heat.
Regardless of how you find them, you want to find the area they think is suitable to colonize—the ants are cluing you in to a moisture problem that can lead to other issues like mold.
2. Determine if action is necessary
If you see a few ants with wings crawling around, they are likely coming in from an outside colony. Simply suck them up with a vacuum and make sure there are screens on the doors and windows. It never hurts to do the cultural and mechanical control actions listed below too.
Carpenter ants will often have main colonies outside that set up satellite colonies to gather resources. It’s likely a satellite colony you’re dealing with inside. Look around the property for a tree or stump that has a lot of carpenter ant activity on it. Call a professional and discuss your options for getting rid of this main colony that is likely sending out foragers (wingless and looking for food) or swarmers (winged and looking for real estate).
If there are tons of winged ants inside crowding a window there is likely an established colony inside that got big enough to send out swarmers. Use a vacuum to suck up the swarmers and look inside for the colony. You’re going to need to take action.
3. Plan treatment and take action
Cultural control: Have residents clean up food and dry up moisture, especially in the kitchen and bathroom. Run a dehumidifier or fan and keep doors and windows closed or screened. Vacuum up any ants you see.
Mechanical control: Suck up ants with a vacuum, repair moisture-damaged wood or insulation, and keep branches from creating bridges to nature (aka touching the building). If there is an underlying cause for the moisture damage like clogged gutters or improper drainage, fix that too. And remove downed trees, stumps, and decaying wood from the property. (Fun fact: Before I got into structural pest control, I operated stump grinders...I "got to the root of the problem" and ground up many carpenter ants with a 60HP piece of machinery!)
Biological Control: N/A.
Chemical Control: If vacuuming out the colony and repairing the damaged area doesn’t solve the problem, bait formulations are usually the way to go. As with any pesticide application, in most states a licensed PMP has to be the one applying pesticides in rented housing.
If you’re reading this because you’re a private homeowner wanting to solve this problem on your own, make sure the pesticide label lists “carpenter ants.” From http://www.extension.org/pages/23619/structural-and-public-health-pests:-carpenter-ants: “Containerized baits and liquid or gel baits placed in inaccessible areas reduce potential for exposure. Containerized baits or reusable bait stations can be placed near ant trails. Liquid or gel baits can be placed in cracks or crevices adjacent to trails or nests. Baits may take up to 60 days to eliminate the colony. Replenish baits as needed until ants are no longer present. Dusts may also be applied in a manner that greatly reduces exposure potential, including into voids reached by removing electrical outlet or switch plate covers, or in holes drilled for in infested wood and sealed after the application. Applications of residual-active pesticides to exposed, human-contact surfaces on the interior or exterior of structures, and use of Danger or Warning-label pesticides, are typically not needed and should be avoided. In addition, barrier applications to exposed impervious surfaces including foundations, walkways and driveways are prone to runoff into surface water and should be avoided.”
4. Evaluate effectiveness
Some signs that you’ve won the battle are that the ants stop taking the bait, you don’t catch any on sticky trap monitors put out in areas where you saw activity, there are no more sawdust piles, and residents don't report seeing or hearing any ants late at night.
These pests are common in nature so you should keep an eye out for them at all times. An IPM practitioners job is never done—manage pests by inspecting for pests and pest-conducive-conditions regularly.