Africanized bees, also known as "killer bees," live in South America, Central America, eastern Mexico and the southwestern United States. The bees, which originated in Africa and were imported to Brazil, are the result of breeding between the African honey bees and European honey bees.
In 1956, colonies of African honey bees were imported into Brazil in order to crossbreed them and increase honey production. The resulting breed escaped from an experimental apiary and bred with local populations of European bees. Since then, they have spread northward, working their way through South America and Central America. They eventually reached southern Texas in 1990 and California in 1995. As of 2014, researchers expect more colonies to form in the southern United States.