“The fly, Apocephalus borealis, deposits its eggs in a bee’s abdomen. Usually about seven days after the bee dies, fly larvae push their way into the world from between the bee’s head and thorax.

After being parasitized by the fly, the bees that survive abandon their hives to congregate near lights.

“When we observed the bees for some time - the ones that were alive - we found that they walked around in circles, often with no sense of direction,” said Andrew Core, an San Francisco State graduate student from Hafernik’s lab who is the lead author on the study.

The San Francisco State team surveyed local bee populations and found evidence of the parasitic fly in 77 percent of the hives they sampled in the Bay Area, as well as some hives in California’s agricultural Central Valley and in South Dakota.

For his presentation of the bee research, Core won first place at the 2011 California State University Research Competition and the Geraldine K. Lindsay Award for excellence in the natural sciences at the annual meeting of the Pacific Division of the American Association for the Advancement of Science.

Bees usually just sit in one place, sometimes curling up before they die, said Core. But the parasitized bees that were still alive were unable to stand up on their legs. “They kept stretching them out and then falling over,” he said. “It really painted a picture of something like a zombie.”“