Africanized bees

Africanized honey bees, known colloquially as "killer bees," are some hybrid varieties 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 hybrid bees are far more defensive than any of the various European subspecies. Small swarms of Africanized bees are capable of taking over European honey bee hives by invading the hive and establishing their own queen after killing the European queen.

• http://en.wikipedia.org/wiki/Africanized bees