[eyespysomething]

They do migrate. If you kill them and your neighbor does nothing, they'll move next door and then back into your yard (if they find it better). And use a bait product to kill them, sprays don't work, and may make the problem worse.

They'll be dormant, way underground, when it's cold, but active again when it warms back up.

Boy, I'd hate to have fire ants in my house. That's scary!

[PJ-Comix]

Fire ants aren't even native to North America. I understand they escaped from a Brazilian boat in the port of Mobile, AL about 70 years ago.