Actually, yes and no. Cow killers are actually wingless wasps, so if you are allergic to bee stings, it could be lethal. If your not, it will just hurt like hell for an hour.
First of all, the cow killer or velvet ant is actually a wasp that delivers a very painful sting. However, I really don't think that a sting from one of these wasps could kill a cow.
Because if it can kill a cow, approximitly it will be hard to kill.
The beetle that closely resembles an ant in appearance is called a "velvet ant" or "cow killer ant."
The "cow killer bug," scientifically known as the red velvet ant (Dasymutilla spp.), is a flightless wasp found primarily in the United States. Despite its name, it is not an actual ant but a member of the Mutillidae family. Its striking appearance features a bright red or orange body covered in dense, velvety hair. The female possesses a potent sting, which is said to be extremely painful, hence the nickname "cow killer."
An ant killer that would get of them for good would be Raid Ant Killer. It is very powerful.
An ant cow is an aphid from which ants obtain honeydew.
Cow killer. Its a wingless wasp that looks like a huge red ant, may not always be red. But most of the time is.
You might try application of loose tobacco or baking soda to the sting. The cow ant (aka cow killer or velvet ant) is actually not an ant, but a wingless wasp, and insect sting swabs which are now available in some first aid kits might be effective.
Yes, ant killer can be toxic to cats if ingested. It is important to keep ant killer products out of reach of pets to prevent accidental poisoning.
I really hope you are asking about a "cow-killer ant" and just just a "cow killer." If you're asking about the former, then try the following: Step on it. Spray it with Raid or some form of wasp killer. If you're asking about the latter, that's something which is condoned on this website, since it is an illegal act of violence to kill another human, even if they make a living killing cows at a slaughter house.
BOOTS.
The ant you are describing is likely a red imported fire ant (Solenopsis invicta). These ants are aggressive and their bites can cause a burning sensation due to the venom they inject into the skin. If you encounter them, it is best to avoid them as their bites can be painful.