Ants: Unwelcome Visitors to Your Yard

One sure thing about winter rains—they’re awfully good at driving ants inside the house. But if you want to get rid of ants, you have to track them to where they live in your yard.

I’ve seen a few ants crawling around my kitchen lately, and I know it’s just that time of year. But there are some things you can do now to prevent ants from taking over your abode.

There’s not much mystery as to why there are ants invading our space—after all, some 270 species of the insect live in California—but there are some ways to discourage them from inhabiting our homes and yards.

One of the most common ants in the Central California area is the Argentine ant, which made its way to North America from its native habitat and now is particularly good at infesting human spaces in urban and suburban areas. The Argentine ant not only goes after and kills native ants, but it also establishes dense populations wherever it settles.

Californians will often see ants inside their homes at two particular times of the year: in the winter after heavy saturating rains, and in the summer when things get very dry.

There are two entirely different reasons for this, according to Wayne Bellville, pest control department manager for Casner Exterminating Inc., which serves Santa Clara County and other regions of California.

“During the summer, ants come in the house looking for water, and while they’re there, they forage for food,” said Bellville. “In the winter, you see them when they get flooded out of their nests and are looking for dry places.”

When you want to stop ants is in your yard, there are a few ways to do it safely. Discouraging ant nests in the garden is important, because they can go after your plants—especially roses and citrus—as well as your home. Also, it’s not pleasant to dig into the ground and find your hands covered in ants.

Bellville suggests drawing the ants away from living spaces by using a lure, which you can make yourself.

“You want to bait them away from the house,” Bellville said. “I usually use white corn syrup because they go after sweet things.”

He’ll drizzle the syrup in a far corner of the yard, leading the ants there, and then he’ll put out ant bait made from a mixture of corn syrup and boric acid, which is poisonous to ants. They will take it back to their nest and share it with the other ants, eventually killing the entire nest.

The website Living With Bugs provides a recipe for homemade ant bait made of 1 tablespoon corn syrup plus ¼ teaspoon boric acid, mixed with an equal amount of warm water. Since some ant species seek fats rather than sweets for sustenance, the site recommends adjusting the recipe if the ants aren’t responding by adding a few drops of vegetable oil.

The bait can be put out in the yard on pieces of wax paper or in a small plastic dish.

This is a relatively non-toxic solution. Boric acid is a naturally occurring mineral in California, and although it affects ants greatly, such small amounts won’t harm pets or children.

Of course, commercial ant bait with boric acid is also readily available, with some popular brand names being Terro and Hot Shot.

Ant bait is the best solution, because it will wipe out the entire nest rather than a few individuals, which is what sprays like Black Flag end up doing. Sprays might solve the problem for a day or two, but if the nest exists, ants will be back.

Instead, use ant bait and give it a chance to be effective, which could take a few days.

And when is it time to call in the exterminator?

“When you’ve tried everything else and nothing works,” Bellville said.