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News / Clark County News

Living-space invaders: Sugar ants on the prowl for moisture

Dry, hot summer after mild winter has them marching into homes, apartments much later than usual

By Zane Vorenberg, for The Columbian
Published: August 25, 2018, 6:00am
5 Photos
Gabriel Bunker, technician with Antworks Pest Control, sprays Transport Mikron around the floorboards of a home in north Vancouver on Friday while searching for sugar ants.
Gabriel Bunker, technician with Antworks Pest Control, sprays Transport Mikron around the floorboards of a home in north Vancouver on Friday while searching for sugar ants. (Nathan Howard/The Columbian) Photo Gallery

If you’re afraid to put a crust of bread on the counter for fear of swarms of tiny sugar ants, blame the weather.

The unusually hot and dry weather has created perfect conditions for the ants, also called odorous house ants, to extend their active season well beyond its usual end in the early summer. Local pest control companies say they’ve seen a marked uptick in calls to exterminate the tiny invaders, but until the rainy season kicks off, the unwelcome house guests are likely to remain.

“We’ve had a very mild winter, combined with what could be the hottest summer on record,” said Joseph Hampton, owner of Aspen Pest Control. “I think the weather is a factor, and the ants are going after water because it’s been so dry outside. For this time of year, we’re about 25 percent above average for customers calling about ants.”

Sugar ants, which are native to the Pacific Northwest, are usually most active starting in late February and into early spring. Calls to pest control companies usually start to drop off in early summer, but not this year, Hampton said.

“This year it really hasn’t stopped at all,” Hampton said. “We’re also seeing more stinging insects than we’ve ever seen at our company. We’re getting more calls on yellow jackets and wasps than ever before.”

Clinton Rockey, a meteorologist at the National Weather Service in Portland, said he’s got a sugar-ant infestation at home himself. Estimating longer-term weather patterns this fall, he said he thinks it’s unlikely the activity will change until at least mid-September.

“I’ve got ants coming in and stealing cat food,” Rockey said. “I don’t think we’ll see the ants calm down until the first rains come in. It’s the height of the dry season, and they’re out there stockpiling anywhere they can.”

Wasps and hornets, which also have booming populations this year because of the weather conditions in the Pacific Northwest, will likely remain very active until temperatures drop into the 40s at night, which usually happens in mid-October, he said.

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“Wasps and hornets are always a problem when it gets dry,” Rockey said. “You probably won’t see those populations go down for a while.”

Portland and Vancouver are both about 6 to 7 inches below normal for rainfall this year, which isn’t stunningly dry, but is dry enough to cause problems. And the upcoming winter is looking like it will be milder than usual, he said.

“We’re looking to be in kind of a weak El Nino pattern this winter,” Rockey said. “That tends to be more mild. This has been a long summer, and we’re in kind of a holding pattern for now. But if we could get wet weather soon, that would sure be nice.”

Thirsty ants

While ants seem to be most interested in finding food, that’s actually not their top priority when they invade homes, said Dan Sale, founder of Antworks Pest Control.

“They’re looking for condensation on pipes and other water sources,” Sale said. “They’re looking to nest for the winter, and if they find continuous moisture, they set up house. That’s why you usually see them in the kitchen or the bathroom. It’s shelter and moisture they want. The food is a bonus.”

Sugar ants are called odorous house ants because if you crush them, they give off an odor that’s unappealing to predators. The ants also are unusual in that they have several queens per nest, and those queens can divide the population and start new nests if their original nest is threatened.

That means you need to have a certain strategy to fight an infestation. Over-the-counter ant sprays don’t work well, because they only deter ants — and when deterred, sugar ants tend to split their colonies to scout the surrounding areas, Sale said.

“If you’re going to use anything, you can use bait,” Sale said. “Terro makes the most popular traps. But only use bait. Over-the-counter sprays make the problem worse and harder to get rid of.”

Fast-acting ant killers may kill ant colony members too quickly, often before the spray can kill any of the queens. Traps are better because it takes a few days for the ants to saturate the colony with the deadly bait. That gives more ants, and hopefully queens, more time to eat it.

“If you have a fast-acting, highly repellent spray, that stresses the foragers,” Sale said. “And when that happens, they divvy up the nest and go off in different directions. Baits may take a long time, but they don’t make that problem worse.”

In reality, nothing is going to kill off all of the sugar ants found in soil around a house. There are far too many of them in the region. Traps can help, and a visit from an exterminator can knock populations back significantly, but because sugar ants are everywhere in the environment, they usually find ways to return, Hampton said.

“One thing you can do as a preventive measure is to keep the vegetation cut back around your home,” Hampton said. “Vegetation is a factor in drawing ants to your house, and they sometimes follow the moisture inside.”

Gardening right next to the house, unclean gutters and trees that touch a home can also turn into travel pathways for ants, he added.

One bit of good news: Carpenter ants, which actually destroy wood, are not any more active than usual for this time of year. Sugar ants, in comparison, don’t destroy building materials. They’re much more of a nuisance than something that can cause serious damage, said Mark Strazhari, owner of Wayfare Pest Solutions.

Bats, yellow jackets

But the warm, dry weather is also increasing populations for some other creatures that seem unusual for the Pacific Northwest.

“Bats are also on the rise,” Strazhari said. “They’re becoming acclimated to living in buildings. We also have black widow (spiders) in the area now. And then there are the wasps and yellow jackets.”

Yellow jackets are usually territorial and chase other yellow jacket populations away if they get too close. But if the heat and humidity in an area are at just the right level, the yellow jackets suddenly get along and don’t chase each other. And that’s what’s happening this year, Strazhari said.

“We’re seeing nests that are 10 feet from each other, with the yellow jackets getting along,” Strazhari said. “I’ve never seen anything like it. It’s a subtle change in heat and humidity, a little warmer and drier, and now we’ve got the biggest yellow jacket invasion in Oregon and Washington history.”

Rockey said he’s not yet ready to tie the unusually warm, dry weather to climate change just yet, noting that it could just be part of a cyclical pattern.

“I think it’s just typical summer weather, when it’s a bit drier than usual,” Rockey said.

But Strazhari said that with so many hot summers in recent years, he thinks climate change is playing a role.

“It’s an interesting season in the Pacific Northwest,” Strazhari said. “The climate shift — no matter what your politics are — if you’re in this business, you can see it.”