You're minding your own business in the kitchen when you think you see a little black dot moving across the floor. You try to think nothing of it, but over time, that one black dot becomes more black dots, and suddenly there's no denying it - you have ants.
Ants are notoriously social insects that live in colonies from hundreds to millions of ants. Most common in warmer, rainier seasons, the main ant types that invade homes are acrobat, fire, rover, carpenter, pharaoh, and odorous house ants, though there are tons of different types of ants that range in size, color, and aggressiveness.
Just because they're small, doesn't mean they can't do real damage. Ants can get into your food, damage property, and plants, and even leave bites that sting.
Understanding how ants operate is crucial to fixing an ant problem. The key player in an ant colony is the ant queen, who lays in her nest, out of sight, and produces the eggs that become the colony's future ants. The queen ant is much larger than the worker ants (the ones you see scurrying across the kitchen floor), and needs to be fed constantly so she can make more eggs. When worker ants set off on their journey through your house, they're looking for food to bring back to the queen, and if you want to eliminate a colony, you need to start at the source.
Spraying ant colonies doesn't work because the queen ant will simply make more worker ants to replace the dead ones. No matter how many ants you kill, it will always look like there's the same amount or more if the queen is still at work reproducing.
While it takes patience, the best thing you can do is watch where the ants in your home are coming from and try to identify what their source of food is. When a rogue ant leaves the nest to scout for food, once it finds something, it'll bring a sample back to the nest and leave a scent trail so that his fellow ants have a way to return to the food source and bring back more for the queen.
Use the worker ants to your advantage by setting up bait stations in the areas where you've seen ants coming and going. The unsuspecting workers will find the ant bait, carry it back to the queen, eventually killing her and cutting off future ant populations. Meanwhile, remove the ants' former food supply if you were able to identify it. It's important that you don't clean away the ants' scent trails for the first few days so that worker ants continue being lead to the poison bait instead. If an ant colony is considerably large, it may have several queens and can take up to a few weeks to kill off the whole colony. Be mindful of the bait stations, as they may empty out and need to be replaced if you've seen a lot of ants passing through.
Once you've noticed a significant drop in ants in your home or if you manage to find the nest this is the time to spray insecticide to kill off any remaining workers.
If you'd rather redirect an ant colony than wipe it out with poison, white vinegar is a super cheap ant repellent that works two ways. First, ants hate the smell of white vinegar and won't want to be anywhere around it; and second, white vinegar destroys the scent trails ants leave behind to remember where they found food.
Using a mixture of half water, half white vinegar, wipe down floors, corners, countertops, cupboards, or anywhere you see ants, repeating the process every few hours to keep the vinegar scent at its strongest and most effective. (Note: Vinegar is not safe for natural stone countertops. Granite, marble, quartz, or other stone types should be wiped down with a regular spray cleaner instead to throw off ants' scent trails.) Pay special attention to the specific areas you've seen ants following trails and concentrate your application there.
Other natural ant repellents include:
Since ants are so tiny, they can enter homes through cracks and crevices that may be hard to see. Check to make sure windows, doors, and all cable entry points are fully sealed. Remember that ants are living things and need water, food, and shelter to survive. So don't make your home a welcoming ant haven by leaving out food. Always keep floors swept, and food sealed and secured.