The zombees are spreading.

Or rather, “zombie bees” – honey bees that have been inhabited by tiny flies that cause them to abandon their hive at night and lurch about erratically before dying. 

"They basically eat the insides out of the bee," said San Francisco State University biologist John Hafernik.

Hafernik first discovered zombie bees in 2008 in California and now uses a website to recruit citizen scientists to track the infection across the country.

The zombee condition recently crept into Washington state. Novice beekeeper Mark Hohn spotted bees jerking about outside his suburban Seattle home.

ZombeeWatch.org

ZombeeWatch.org, managed by John Hafernik at San Francisco State University, solicits information from citizen scientists, beekeepers and enthusiasts to track zombie bees.

"I joke with my kids that the zombie apocalypse is starting at my house," Hohn said.

Hohn collected several of the corpses and popped them into a plastic bag. About a week later, he had evidence his bees were infected: the pupae of parasitic flies. They were the first to be confirmed in Washington state, The Seattle Times reported.

The infection could be another threat to bees needed to pollinate crops. Hives have been failing in recent years due to a mysterious ailment called colony collapse disorder, which causes all the adult honey bees in a colony to suddenly die.

Still, there’s no evidence that the parasitic fly is to blame, said Steve Sheppard, chairman of the entomology department at Washington State University.

Related: Fly parasite turns honeybees into zom-bees

The fly-bee relationship is a strange one: The flies, discovered in Maine in 1924, are native to North America. Honey bees – what scientists call the “beneficial insect” – are not.

So why haven’t the flies feasted on honey bees before now?

“We don’t really know if this is something the flies have figured out recently or if it’s been under the radar,” Hafernik told NBC News.

It’s possible this behavior has gone undetected – after all, infected bees abandon their hives at night, when beekeepers aren’t around to notice.

But Hafernik has trouble believing that dedicated beekeepers and scientists have gone decades without noticing infected bees.

In the San Francisco Bay Area, Hafernik said, up to 78 percent of hives are infected, and a number are infected across the Pacific Northwest. Scientists conducted DNA analysis on bees found traces of parasites in bees in South Dakota; there have also been cases in New York, Minnesota and Colorado. 

“It could be that not all honey bee strains are susceptible to the fly at the same rate – there could be some genetics among the honeybees that could be brought to bear,” Hafernik said.

He hopes that scientists and beekeepers will send information to his website, ZombeeWatch.org, so that his team may better research the problem.

Hafernik said that those suspecting zombie bees should isolate the bee for about a week as Hohn did – the bee will die within a day or two if infected. After five to seven days, maggots will have finished their feeding and emerge from the bee’s head – those look like small, brown, crystal-shaped pupae. Take photos, he asks, and send them along.

Hafernik will also be taking notes. After a recent vacation, he found that a colony of infected bees had moved into a crevice next to his house.

“They’re now living between the walls of my house,” he said. “I decided to leave them. For the moment, we’re coexisting peacefully.” 

NBC's Isolde Raftery contributed reporting.

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