This is an Argentine Ant.
How to identify Argentine Ants:
Argentine Ants can be identified by their multi-segmented antennae. It's divided into 12 segments. They are brown ants with shading from light brown to dark brown. These ant colonies can be run by a couple Queens, or be extra large and have have hundreds of Queens. They can be found in a lot of locations but generally like to be where it's moist, like water leaks, creeks, lakes or under houses and decks. One thing that makes these ants stand out from other ants is that they are pretty much the same size and physically look the same. Even their Queen has been sized down. This is different because some other types of ants might have a physically larger Queen while the workers are small.
What do Argentine Ants eat?
Argentine Ants are not picky. While they do prefer sweet foods they will eat wood (especially with sweet sap in it) and destroy trees. They will munch on cat food or make a feast out of a dropped french fry. This is can be acceptable in a public park for instance, but not so much when they are invading your house.
How do Argentine Ants get into my home?
Argentine Ants are tiny so they can slip through the smallest cracks in wood, brick, mortar, windows, pipes, etc. They can climb up your house into your attic, make a home there, and then head back down to steal food from other areas of the house.
How do I get rid of Argentine Ants?
These little guys will keep coming back again and again. You have to exterminate them at their source, then seal up all the tiny cracks they can use to get into the house so a new colony does not come along next year.
Image credit - Wikipedia Commons