I saw a Texas fire ant once near Dallas as kid — the thing was the size of a tarrantula. Was told its venom is lethal.
No, this isn’t Texas humor. And I have some of them on my yard in south Virginia. Fast moving and they like to chase people. Thank God their population is tiny. Rarely see them.
A man nearby stomped it to death with his boot heel.
Is sounds like you’re talking about a red velvet ant, or cow ant. It’s not actually an ant because it eventually grows wings and becomes a wasp.
One of them bit me when i was a kid. It hurt a LOT, more than a red wasp or asp or even a handful of fire ants. Cow ants can be huge but they don’t really kills cows; it’s just a figure of speech (”That thar thang hurts enuf to kill a cow!”). They do move fast, though, especially if you’re chasing them. I think they must have poor eyesight because sometimes they do seem like they’re chasing the person who’s trying to stomp them. lol!
Go find the images of these beasts and you’ll know if that’s what you’re talking about or not. The Texas fire ants are small. They’re all over my yard after every rain and are the scourge of Texas!
About the cow ants: I’ve spent decades killing every cow ant I’ve even seen. They are evil!! As much as it hurt when I got bit, I figure an entire lifetime of smashing those creatures STILL won’t be enough payback!