Every now and then especially when it rains, these safari ants move in large numbers either to a food source or maybe from nest to nest.
As you can see, there are soldier ants who are on standby everywhere along their trail.
If you happen to step on them as you walk along, you're bound to pick a few which will surely bite you in defense, or when they realize you can be a good source of food.
I've noticed that they aren't too keen on climbing certain running shoes, the kind with synthetic woven fabric. Maybe it's because they can tell they are not made of organic matter. But with slippers or rubber sandals, they will climb, and boy, is it painful when they bite under the toes...
...or when they make their way all up to your crotch!
I don't know if it is true, but if you are a camper and they find you while you are asleep, ashes may help to soothe their bites and repel them from trying to feed on you/attack in defense of the colony.
Their bites are not poisonous.