Killer bees fully colonized Los Angeles County by 1999 and have almost completely pushed out the existing wild bee population. The bees can attack when an intruder gets closer than 100 feet, can chase a person up to a half-mile and will remain aggressive up to an hour after an attack, according to the county.
Those who work with feral bees insist that the concerns are overblown.
Feral bees in Los Angeles do have some African genes, they say, but the danger has been diluted from years of interbreeding with local, non-Africanized bees.
There are already around 10 feral hives per square mile in Los Angeles, so moving them to backyards where beekeepers can monitor them makes sense, said Ruth Askren, who maintains hives for 22 clients and has relocated wild hives to backyards all over the city.
Beekeepers like Askren estimate that 10 percent or fewer of the feral hives they relocate are so aggressive they must be destroyed.
"If we really had serious Africanized bees in LA, people would be chased down the street every day," she said.
Africanized bees are also hardier than their European counterparts, which are used for commercial pollination, and could help counter colony collapse, said McFarland, the rooftop beekeeper.
"We need them. We need to preserve what's clearly a superior bee. They're the ones that are surviving," he said. "My opinion is that they're a blessing in disguise."
Feral bees have also sweetened the pot for an emerging niche business: Some beekeepers-turned-entrepreneurs have recently started companies to remove unwanted wild hives, relocating them to backyard bee boxes and then harvesting rich honey that can sell for $110 a gallon to wealthy foodies obsessed with local ingredients.
Some customers even want honey made by bees in their specific neighborhood because they believe that eating honey made from local pollens will combat allergies.