The Africanized bee, also known as the Africanised honey bee and known colloquially as “killer bee”, is a hybrid of the Western honey bee species (Apis mellifera), produced originally by cross-breeding of the African honey bee (A. m. scutellata), with various European honey bees such as the Italian bee A. m. ligustica and the Iberian bee A. m. iberiensis.

The Africanized honey bee was first introduced to Brazil in the 1950s, in an effort to increase honey production; but, in 1957, 26 swarms accidentally escaped quarantine. Since then, the species has spread throughout South America, and arrived in North America in 1985. Hives were found in south Texas of the United States in 1990.[1]

Africanized bees are typically much more defensive than other races of bees, and react to disturbances faster than European honey bees. They can chase a person a quarter of a mile (400 m); they have killed some 1,000 humans, with victims receiving ten times more stings than from European honey bees.[2] They have also killed horses and other animals.

The first Africanized bees in the US were discovered in 1985 at an oil field in the San Joaquin Valley of California. “Bee experts theorized the colony had arrived hidden in a load of oil-drilling pipe shipped from South America.” The first permanent colonies arrived in Texas, from Mexico, in 1990. In the Tucson region of Arizona, a study of trapped swarms in 1994 found that only 15 percent had been Africanized; this number had grown to 90 percent by 1997.