I heard they had ants from South America smuggling cocaine into the country, one flake at a time. Some dude named Ricky found out and started snorting the line of ants. He got as far as Tiajuana before his head was the size of a beach ball. The Mexican kids, assuming he was a piñata, busted him upside the cabeza with a stick until he exploded ants all over them. That why those Mexican kids are so itchy, all the pinche bites.
Many of the coke ants made it to the States and now live in one of Keith Richards' old guitar cases which they snuck into during the Stones' last tour.