In 1957, 26 colonies of African honey bees escaped from an experimental apiary in Rio Claro,…

In 1957, 26 colonies of African honey bees escaped from an experimental apiary in Rio Claro, São Paulo, after queen-excluding screens were removed without authorization. These bees interbred with established European honey bee populations in Brazil, creating hybrid 'Africanized' bees that thrived in tropical climates and expanded across the Americas.

The experiment aimed to improve Brazilian beekeeping by introducing African bee lineages better adapted to tropical conditions. Geneticist Warwick Kerr collected queens in Africa in 1956 and brought them to São Paulo for controlled breeding. The queen-excluding screens were intended to prevent escapes and control reproduction, but their removal led to the unintended release of 26 queen bees.