Africanized honey bees, also known as killer bees, will soon make their debut in Southern California, according to those closely tracking the bees' northward migration from South America. The temperamental bees, which look no different than the common European honey bee, are southwest of Yuma, Ariz., and could cross the Colorado River into California any time. "No one has discovered a way to stop the spread of the Africanized bees," says Eric Mussen, a UC Davis Cooperative Extension apiculturist, who is helping prepare California beekeepers for the invaders' arrival. "Once they're here, we're going to have to learn to live with them and avoid them as much as possible."