(Africanized Honey Bee)
The Africanized honey bee does not differ that much from its domestic cousin. They look exactly the same, except the killer bee is generally smaller. Additionally, their stings are equally venomous. The big difference is in their behavior. The killer bee is extremely aggressive and easily agitated. Also, Africanized bees attack in larger numbers and pursue over a greater distance for a longer period of time. Reports of deaths from these attacks have earned them the name of "Killer Bees".
Source: Insecta Inspecta