[view·edit·purge]Africanized honey bees, known colloquially as "killer bees", are a hybrid of the Western honey bee species produced originally by cross-breeding of the African honey bee with various European honey bees. The African honey bee was first introduced to Brazil in the 1950s to increase honey production, but, in 1957, 26 swarms escaped quarantine and, since then, have spread throughout South, Central and North America.
Africanized bees are characterized by far greater defensiveness than European honey bees. They are more likely to attack a perceived threat and, when they do so, attack relentlessly and in larger numbers. They have been known to pursue a perceived threat for a distance of well over 500 meters. This aggressively protective behavior has earned them the nickname "killer bees".