Ants invading Bay Space properties after epic storms. Right here’s what to do

After dealing with flooding, wind damage, downed trees and power outages during historic winter storms, Bay Area residents are reporting a different type of wet weather outcome: ant invasions.

“Long, irritating, invasive tapes of theirs,” a Bay Area resident said on Facebook.

“We had a full invasion,” said another.

“I’m from San Francisco and I don’t remember ever having ants in the house like we’ve had for the past few years,” Madison Smith, 37, told The Chronicle. “We find ants mainly in the front bedrooms, and then in the basement and bathroom.”

Experts say such unwanted incursions are common during the winter months — especially after heavy rains that soak the ground and drive ants out of their nests or ruin their food.

“Their invasions typically occur in winter, especially after heavy rains have inundated their outdoor nests, or in late summer when we’re having our hottest weather and they need to find cooler, wetter conditions,” said UC Berkeley professor and insect behaviorist Neil Durie Tsutsui .

Zach Smith, owner of Smith’s Pest Management in San Jose, said he’s definitely noticed a difference this season.

“It’s absolutely worse and we’ve had more calls than ever about ants and rats,” he said. “Even during those first rains in December, the calls came in. It seemed such an unforgiving winter.”

Here’s what you need to know about the ants and how to stop them from taking over your home.

What types of ants come into my house?

The typical native invader in the Bay Area is the Argentine ant, or Linepithema humile, an invasive species that originated in South America, Tsutsui said. According to Zach Smith, these ants produce super colonies and work together harmoniously.

The smaller scented house ant is another common animal, said Matt Fisher of Omega Termite and Pest Control.

Why are ants invading now?

Ants are driven indoors by two things, Tsutsui said: bad conditions outside — like rain or heat — and food.

“The series of atmospheric flows this winter have saturated the soil and driven Argentine ants into unusual nesting sites, leading to many home invasions during the winter,” he said. “These invasions are usually temporary, and the ants return outside when the weather is more pleasant.”

If things dry up, the ants will be out and about again looking for new homes, which means fewer ants live with us, Tsutsui said. But if they find food indoors, they can become your new housemates.

How do they get in?

No matter how well built your home, ants can still likely find a way inside, experts said.

“Houses are so porous,” said Zach Smith. “There are a dozen ways into any well-built house…Anything a needle can pierce, ants can pierce.”

According to experts, ants enter through cases around windows, gaps between floor and wall or around doors, or through cracks in exterior stucco. They move through walls and emerge indoors from sockets or baseboards. Plumbing is associated with perforations around the house. So if you don’t have enough sealant, ants can get into those areas, too, Smith said.

Ants could sometimes move their entire colony into wall cavities, Fisher said.

“They don’t usually stay there very long, they’re just trying to escape the moisture,” he said. However, “Sometimes they move in and open a shop, so it’s a bit harder for people to get rid of them.”

Once indoors, their favorite rooms tend to be kitchens and bathrooms because they like areas with some moisture and natural food sources.

How to stop ant invasions?

When ants arrive, the best solution is to use ant baits with sugar and borax or boric acid, such as B. the Terro brand. Place the self-contained bait stations in areas where you’ll see ants invading or traveling — and most importantly, “Don’t mess with the ants that start taking the bait,” Zach Smith said.

The ants bring the bait back to the nest to share. So if you start spraying them, the bait will not be able to do its job.

Another good strategy is to trace the ants back to their outdoor source and place the traps there if possible, which Fisher says will lure them away and discourage them from congregating indoors.

Keep in mind that the process will likely take some time, the experts said.

“Allow the ants to feed on the bait, which could take weeks,” Fisher said. “Don’t put the bait on the kitchen counter unless you have the patience to watch ants for weeks.”

Also, resist the urge to spray the ants with over-the-counter products, he said. This temporary solution can keep them from going to a certain area, but not leaving it for good.

When do I need to call an exterminator?

Calls to pest control companies are typically reactive responses to ant invasions, Fisher said. He advised taking proactive steps to keep ants at bay before you have a problem.

This strategy worked for Madison Smith, who lives in San Francisco.

“This year we were able to overtake them early enough to avoid a major invasion,” Smith said. “Our tree outside has a root system that extends below the foundation of our house, and we think the ants got in through the rat screen in the basement.”

She said after an exterminator she hired a few years ago had success with Optigard ant bait gel, she now buys it from Amazon and uses it herself.

“While it doesn’t necessarily stop them from getting in, it stops the invasion within 36 hours and works better than any other baiting system we’ve tried,” she said.

But if what you’re doing isn’t helping, it might be time to call in a professional.

“Often people do it themselves but lack confidence and may be on the right track but give up,” said Zach Smith, owner of a pest control company in San Jose. “We can take care of it”

“We know our products and may need to come back a few times,” he said.

How do I prevent ants in the future?

Depending on the season or what is happening in their colonies, ants look for either sugar or protein. Tsutsui said Argentine ants generally have a sweet tooth and are particularly attracted to anything sweet, from soda to honey to leftover candy.

“However, in spring and summer, they need more protein to feed the large numbers of growing baby ants in their nests,” he said. “During these times of population growth, Argentine ants often swarm on higher-protein foods, such as: B. Pet food left unattended.”

Start repelling ants early to avoid infestations. Now is a good time to reduce the ant population before it gets warm. Also, keep your home as clean as possible, inside and out.

Zach Smith recommends clearing outdoor clutter, including tarps and stacks of firewood, which can attract ants and rodents. Old tree stumps are also a popular hiding place.

He also advises getting kitchen appliances, including the stove and dishwasher, out and cleaning behind them.

Reach Kellie Hwang: kellie.hwang@sfchronicle.com; Twitter: @KellieHwang