Like so many great eureka! moments, biologist John Hafernik’s discovery zombie bees was a peculiar accident.

He found some bees wandering around in circles outside the building where he works, and collected a few in a vial to feed to his praying mantis. But he forgot to feed them to the mantis, and a week later the vial was filled with dead bees and little brown pupae. These turned out to belong to Apocephalus borealis, a parasitic fly that had previously been known to infect bumble bees and some wasps.

He tells the full story in this video:

Hafernik later published the discovery in PLOS ONE. The bees are infected when a female fly pierces a bee’s outer membrane and injects eggs. They hatch and the maggots begin to eat the bee from the inside out.

Then the bee begins to act very strangely. It leaves its hive at night, which bees do not normally do. It flies in circles around a light source, or wanders aimlessly on the ground. Eventually, it dies and the maggots exit the body through the neck.

Hafernik nicknamed these infected insects “zombees” because of their strange behavior. We don’t yet know if they abandon the hives because the maggots commandeer their nervous systems, because they’re seeking comfort from the pain, because they’re trying to protect their colony from infection, or because they get kicked out, Hafernik explains in this interview with KQED Science.

Hafernik has enlisted the help of citizen scientists to sample and monitor the zombee apocalypse. He set up ZomBeeWatch.org, where the public can learn how to collect and share data.

The red markers show where zombee sightings have been confirmed.

All over the country, amateur scientists are sampling dead and dying honeybees and setting up light traps to attract the zombified insects.

It’s not yet clear how devastating the zombie flies are on honeybee colonies. Declining bee populations have been linked to many things, including agricultural pesticides, viruses, and other parasites, like the “vampire” mite.

What is clear is that human activity has dramatically changed the Earth’s environment and created the conditions for new threats against honeybees to flourish.

Want to be a part of the solution? Become a zombee hunter by visiting ZomBeeWatch.org, and check out this instructional video: