Ants in and around the home often cause a bit of disturbance to homeowners. Citronella ants (Acanthomyops interjectus), also called foundation ants and large yellow ants, often cause concern that isn't warranted. Despite their size and innate abilities to enter homes through small cracks when swarming, these ants are barely a nuisance species. They do not forage for food or reproduce indoors and are not built to live in homes or other structures. As such, controlling them in the home is best done with exclusion techniques.
These large, yellow ants are soil-nesting, meaning they prefer to build their nests outdoors in soil, typically under logs, rocks, concrete, porches and other similar structures. They are fairly large ants; workers are typically 1/4 inch long with an orange-yellow body. Homeowners rarely come across these ants except during short periods throughout the year, typically in early spring or late summer to early fall, when swarmers begin looking for mates and to start new colonies. Swarmers are approximately twice the size of typical workers with smoky wings; they closely resemble swarming termites.
Because these ants typically enter homes only during the swarming period, excluding them is one of the simplest and most effective methods of controlling them. They'll often find expansion cracks in foundations or around doorways. Find and fill the cracks in which the ants are coming in. Use caulk or similar materials to fill voids and cracks around the foundation, doors and windows of your home.
A vacuum cleaner can do wonders for ridding your home of swarming citronella ants. If they do enter your home, sweep them up with the vacuum cleaner. A vacuum with a long wand can make the task easier. You can release any that survive the vacuum.
In rare circumstances, these ants nest near or in foundations and crawl spaces, making them more of a nuisance. To control the ants in this type of situation, it is important to find the colony. In general, citronella ant colonies have a mound of soil around the opening. Dusting silica gel or over-the-counter ant controls into the nest with a handheld duster is often effective.