Novice beekeeper Mark Hohn returned home from vacation a few weeks ago to find many of his bees either dead or flying in jerky patterns and then flopping on the floor. He later learned they had a parasite that causes bees to fly at night and lurch around erratically until they die.
The infection is called "zombie bees."
"I joke with my kids that the zombie apocalypse is starting at my house," Hohn told The Seattle Times.
San Francisco State University biologist John Hafernik discovered the infection in California in 2008.
Hafernik now uses a website to recruit citizen scientists like Hohn to track the infection across the country. Observers have found zombie bees in California, Oregon, South Dakota and, now, Washington.
Zombie bees also are being studied by Steve Sheppard, chairman of the entomology department at Washington State University.
The infection is another threat to bees that are needed to pollinate crops. Hives have been failing in recent years due to a mysterious ailment called colony collapse disorder, in which all the adult honey bees in a colony suddenly die.
Hohn had remembered hearing about zombie bees, so when he discovered the dead bees at his 1.25-acre spread, he collected several of the corpses and popped them into a plastic bag. About a week later, Hohn had evidence his bees were infected - the pupae of parasitic flies.
The life cycle of the fly that infects zombie bees is reminiscent of the movie "Alien," the Times reported. A small adult female lands on the back of a honeybee and injects eggs into the bee's abdomen. The eggs hatch into maggots.
"They basically eat the insides out of the bee," Hafernik said.
After consuming their host, the maggots pupate, forming a hard outer shell that looks like a fat, brown grain of rice. That's what Hohn found in the plastic bag with the dead bees. Adult flies emerge in three to four weeks.
There's no evidence yet that the parasitic fly is a major player in the bees' decline, but it does seem the pest is targeting new hosts, Sheppard said. "It may occur a lot more widely than we think."
That's what Hafernik hopes to find out with his website, zombeewatch.org. The site offers simple instructions for collecting suspect bees, watching for signs of parasites and reporting the results.
Once more people start looking here, the number of sightings will probably climb, Hohn said.
"I'm pretty confident I'm not the only one in Washington state who has them," he said.