I looked it up. Sounds like a Ghost Ant. They need excessive moisture and can usually be found in kitchens and bathrooms........OR growrooms.
Usually found in south to central Florida. Not to give away locations or anything, maybe you travelled there and brought some back. Yea yea thats it! (edit: guess you already mentioned that, haha)
They should have a musty odor when smashed... try it!
Also I read you should bait them instead of spraying. With eating baits you can eliminate the entire colony and not just those you have seen. Then again they dont eat vegetation but they will eat other living insects, maybe beneficial? But I would kill them.
Is this it??
....so... but I do still spray every once in awhile..lol...