Q: Why do Africanized bees, the so-called "killer bees," always migrate northward?
A: They don't, according to entomologist Orley Taylor of the University of Kansas. They actually migrate in every direction in which a suitable habitat is available. But they have now occupied all suitable habitats in South and Central America, and the only direction left for them is north.
Researchers do not expect them to migrate farther north than Austin, Texas, or Phoenix, Ariz., because the winters are too long for them to survive. It is not yet clear how far north they will migrate through California's Central Valley, but most researchers expect them to go no farther than San Francisco. One mystery that has puzzled entomologists is why they have not migrated eastward in the United States. "They should be well into Florida now and migrating down the peninsula," Taylor said, but so far there are none east of Houston.