“Zombie bees” are ones infected with a parasite that causes them to fly in abnormal ways and at night before they die. During 2011, at least one published scientific paper explained the zombie bee problem that was extensively identified in California and is now being confirmed or suspected in other areas of the nation where bees are commercially kept.

A number of scientists collaborated to report that the first documented attack by phorid fly Apocephalus borealis, or zombie fly, “previously known to parasitize bumble bees, also infects and eventually kills honey bees and may pose an emerging threat to North American apiculture.”

Parasitized honey bees abandon their hives at night and die shortly afterward, then about seven days later up to 13 phorid larvae emerge from each dead bee.

“Phorid parasitism“ was first determined to be infecting 77 percent of honeybee sites sampled in the San Francisco Bay Area, and analyses detected phorids in commercial hives in South Dakota and California's Central Valley, too. Understanding details of phorid infection may shed light on similar hive abandonment behaviors, it was noted at the time of the 2011 publication of the major research white paper.

A website and citizen science project has been established to determine the extent of the phorid infection, and citizens have provided samples to confirm or eliminate infection in hives. Samples have come from Washington, Oregon, Minnesota, Ohio, Colorado, New York and Connecticut in addition to South Dakota and California.

ZomBee Watch is the project sponsored by the San Francisco State University Department of Biology, the San Francisco State University Center for Computing for Life Sciences and the Natural History Museum of LA County.

ZomBee Watch was initiated as a follow-up to the first discovery that the zombie fly is parasitizing honey bees. The website, https://www.zombeewatch.org/, for the organization provides a link to the research paper: “A new threat to honey bees, the parasitic phorid fly Apocephalus borealis.”

ZomBee Watch has three main goals:

  1. To determine where in North America the zombie fly Apocephalus borealis is parasitizing honey bees.
  2. To determine how often honey bees leave their hives at night, even if they are not parasitized by the zombie fly.
  3. To engage citizen scientists in making a significant contribution to knowledge about honey bees and to become better observers of nature.

According to ZomBee Watch, “in California, parasitism begins to increase in early June and peaks in the fall and early winter months. Most records of the fly from other parts of North America (such as the Midwest and Northeast) are from late May to September, which is the most likely time that parasitism will be observed by citizen scientists in those areas."