Africanized honey bees. Not wasps, bumble bees, etc. Just to clarify for anyone alarmed by this discussion.
I, for one, would not have put any stock in the all-africanized claims, at least based on personal experiences in that region, along the Arizona Trail and Grand Enchantment Trail, and living on and off in Tucson. Even relatively up-close, "I can hear the swarm buzzing" sort of encounters rarely lead to attacks. And honey bees not defending their hives, such as at water sources, tend to be utterly placid in character. No moleste y no moleste.