Most homeowners have found themselves wondering “Why are there ants in my house?!” at least once in their lives. Ants are not the most dangerous or annoying pests to stumble upon in your house but they are still quite the annoyance. Plus, they do carry certain risks with them nonetheless – some ants can carry diseases if you let them near your food supply while other ants such as most carpenter ants can cause quite a bit of property damage. A lot of ants are even capable of delivering painful stings and bites, sometimes even causing anaphylactic shock.

Which types of ants commonly invade homes and why?

There are over 12,000 different species of ants worldwide but most of them rarely have any contact with human beings nor are interested in nesting near us. Of the only several types of ants that might nest in or near a house, none are “looking for houses” to nest in specifically. Instead, they just happen to sometimes nest in houses when they see that they can find the right nesting conditions there. Here are the most common species of ants that might cause an ant infestation in houses or other indoor areas:

Field ants (Formica)

These ants are equipped both with stingers and the ability to spray formic acid from their abdomens. They don’t nest in houses but as they are commonly found in fields in rural areas they can often be seen raiding a kitchen or a storage space.

Dark Rover ants (Brachymyrmex patagonicus)

The medium-sized Dark Rovers love to nest near people and can even nest in your kitchen’s or bathroom’s walls or floorboards. They have a taste for sweet liquids and their large size can make them a nuisance despite the fact that they don’t sting.

Acrobat ants (Crematogaster)

These peculiar insects have evolved the instinct to lift their abdomens when threatened to resemble scorpions. They do sting too and are fairly aggressive but they are not the most frequent home invaders.

Carpenter ants (Camponotus)

Even though they are not as problematic as termites, a carpenter ant infestation is still capable of causing a lot of damage to your house. There are a lot of sub-species of carpenter ants so there is no unified appearance description but they are all generally quite large and have some defining features. They don’t eat wood as termites do but they love to dig through wooden structures to form their nests. As a result of that, finding carpenter ants in houses or other structures is quite a problem.

Argentine ants (Linepithema humile)

These relatively large insects can nest indoors in wall insulations and empty spaces. They do not sting so finding Argentine ants in the kitchen or other indoor settings isn’t so problematic but they are still a nuisance.

Crazy ants (Paratrechina longicornis)

The long-legged crazy ants can’t cause that large of an ant problem in houses but they are still not a pleasant sight to see. They love to nest in plant soil under heavy vegetation but you can also find them under carpets, in house plants or in wall voids.

Asian needle ants (Pachycondyla chinensis)

These thin, narrow ants are known to sting so be mindful if you find them around your house. They rarely nest indoors but love to settle near houses and raid people’s trash and kitchens.

What are ants attracted to in our homes?

As with any other pest, insect or otherwise, ants raid our homes for three things – food, water, and shelter. Unlike other pests who intentionally break into our homes and try to settle in, however, most ant invasions happen just because the ants stumble upon our homes and see the beneficial conditions in them.

Ants spread quite gradually, expanding from one nest to the next every time a new queen takes flight. As we also make our yards and gardens quite ant-friendly, it’s not surprising that ants first settle in them and then soon make the next step indoors.

Not all ants like to build nests indoors, however, as a lot of them prefer nesting in deep, soft soil instead. Still, even the ones that prefer to stay outdoors will raid our trash cans or kitchens if they notice that there is food in them.

As ant queens lay new eggs every day (sometimes in the tens of thousands of eggs per day) they need constant nutrition. So, when ants stumble upon food leftovers in our trash, on the kitchen counter or spilled on the floor, you can’t blame them for taking interest in your home.

Water is another great draw for ants. Especially in drier climates where surface or sub-surface water sources are few and far between, ants tend to circle people’s homes because of the water in them. Whether they take interest in the water on your bathroom’s floor, the water in your kitchen’s sink or water leaking from the pipes into your crawlspace, having excess leaking water is a surefire way to attract ants or other insects.

Last but not least, as studies such as this Stanford study have determined, climate and weather changes can draw ants indoors as well. Particularly in the winter months or during the wet seasons, ants are much more likely to invade your home and seek shelter in it. That’s because their outdoor nests and colonies can often be ruined by excess rain, while indoor nests are much safer.

Similarly, the winter months can force ant colonies to stay underground to preserve body heat, keeping them from hunting and foraging for food. If they manage to settle indoors, however, this can both keep the temperature higher, as well as offer abundance of nearby food sources.