Africanized honey bees are now being found as north as the California delta region, according to scientists from the University of California, San Diego. The scientists collected samples of hundreds of the so-called “killer” bees over the years since they entered California in 1994. Further, they found that in Southern California, 65 percent of honeybees are a mix of the gentler European and new African bees.

Joshua Kohn, a biology professor at UC San Diego co-authored the recent study. Kohn said in regards to the increase in Africanized bees: “The pattern of Africanization we documented in San Diego County and elsewhere in California appears consistent with patterns previously documented in Texas, where Africanized honey bees first appeared in the United States.”

Africanized honey bees are already very common in the American South, Southeast, Southwest, and Western coastal areas of the country. However, they have been unable to set up colonies in more northern areas due to colder temperatures throughout winter. Unfortunately, many are considering global warming as a contributing factor in warming northern areas and allowing for Africanized bees expansion.