ZomBee Questions and Answers


What is a zombee?

A zombee is a honey bee that has become a host for the phorid fly, Apocephalus borealis.

What is a zombie?

Apocephalus borealis is often called a zombie fly.

Why are the two words spelled differently?

I have no clue. Just remember that the infected bee is a zombee, while the fly that does the infecting is a zombie fly.

What is a host?

A host is an organism on which a parasite lives or feeds. In this example, the parasitic adult fly lands on a honey bee abdomen and pierces the exoskeleton with her ovipositor. The fly’s eggs pass through the ovipositor and into the body of the honey bee in just a few seconds. When the eggs hatch, the larvae munch on bee innards. Eventually the honey bee dies and the larvae chew their way to the outside, exiting the bee between the head and thorax.

Once outside the host (outside the honey bee) the larva crawls away from the bee to pupate. The pupa develops a protective envelope where it remains for 5 to 14 days while it transforms into an adult fly. In another 15 to 28 days, the new fly hatches, mates, and goes in search of a new honey bee host for her own eggs.

Why does the fly need a host?

Like a honey bee, the fly undergoes complete metamorphosis. This means there are four distinct life stages: egg, larva, pupa, and adult. Growth is very rapid in the larval stage and much food is needed to support that growth.

Honey bee larva are fed royal jelly, honey, and pollen by the nurse bees. Many solitary bees, on the other hand, eat the pollen and nectar stashes that were collected by the mother bee. But rather than doing all that work, the female zombie fly lays her eggs inside a nice, juicy honey bee. This food (let’s call it a slurp-bee) provides all the nutrition the developing larva needs to grow and thrive.

Think of it this way, instead of bringing food to the baby, the fly brings the baby to the food.

What does the word “phorid” mean?

The family Phoridae is a large one, comprising more than 4000 species in 230 genera. Only the species, Apocephalus borealis, is known to cause zombee behavior in honey bees. “Phorid” is a general name for all the species in the Phoridae family.

What is zombee behavior?

Infection by zombie flies causes unusual behavior in honey bees. Specifically, it causes them to fly out of their hives at night. Once out of the hive, they fly towards a light source as many insects do. But unlike other insects at a light source, the infected honey bees become disoriented and lose their balance; eventually they die. What causes them to leave their hive at night is not known. It could be that the fly larvae interfere with the bee’s biological clock, or it could be something else entirely.

Do zombie flies only infect honey bees?

One of the interesting things about this parasite is that it is native to North America. In the past, it has been known to infect bumble bees and paper wasps. But it is apparent the species has “jumped ship” and now is infecting the non-native honey bee.

Will zombie flies kill my hive?

Probably not all by themselves, but infection may weaken a colony and make it more susceptible to other parasites, pathogens, and predators. In addition, the flies have been shown to carry pathogens such as Nosema ceranae and deformed-wing virus.

Are zombie flies active in my area?

Good question. Not much is known about the distribution of the zombie fly in North America nor the infection rate of honey bee colonies. You can help compile data on this parasite by joining ZomBeeWatch.org and becoming a ZomBee hunter. As a ZomBee hunter, you can set out a light trap and report your findings. You can also report honey bees that you find under a porch light or street lamp.

What is a light trap?

A light trap is just a lamp that you place outside at night. Beneath the light is a container  to capture honey bees that die at the light source.

What should I do with honey bees that died at the light?

You collect your dead honey bees from the container and place them into a different resealable container, something like a mason jar works well. You wait 5 to 14 days, then look for any larvae that crawl out from the necks of the bees—right between the head and the thorax. You also look for pupae and then wait to see if they hatch into adult flies. All of your data and photos are fed into the ZomBeeWatch.org database.

I don’t have a fancy camera, just a cell phone.

That will work just fine, just focus in as close as possible.

So I just wait, and if I see something, I report?

No, and this is a big “NO.” Once you set up a trap, ZomBeeWatch.org wants to know if you captured honey bees OR NOT. And if you find dead honey bees in your trap, they want to know if larvae emerged from the bees OR NOT. These OR NOTs are just as important as the sightings.

Right now there are big holes in the North American map that contain no zombee information. ZombeeWatch.org doesn’t know if this means there are no zombie flies in those areas or if nobody looked for them. If people don’t report negative findings, valuable information is lost. So remember, “Nothing here!” is just as important as “Got one!”

How do I become a Zombee Hunter?

I urge all beekeepers to go to the ZomBeeWatch.org website and sign up. Their website has lots of information and photos, as well as instructions for constructing light traps and submitting your data. Don’t think of it as a chore—this is fun citizen science and a chance to learn even more about honey bees and beekeeping. So go on the hunt and have fun with it!

Zombie fly cocoons and dead honey bees.

Zombie fly pupae and dead honey bees. Photo by Rusty Burlew


  • As I was going through one of my hives the other day, I knowtessed a fly inside the hive. The bees seemed to pretty much ignore it, but I’ve never seen one inside like that before. I’m not concerned about it too much, but I was curious about it at the time and remembered reading this post. Is this something normal, or is it out of character for a “regular” fly to be in a hive? Should i do more checking?

    • Tyrel,

      All kinds of insects and other creatures wonder into bee hives. An individual fly or wasp or beetle is nothing to worry about. Also, a zombee fly is incredibly small, not something you would notice easily. So no, I would not be concerned.

  • We have the zoombee symptoms in at least one hive in Denver. Dozens of bees coming out later (10-midnight) at nite flying around porch lites or even flash lites. Infected bees seem aggressive to load noise as well. This may only be a curiosity to you but for those who raise bees this is serious!! To lose a large hive is hundreds of dollars and years wasted.

    • Cj,

      Hmm. I don’t know what makes you think I don’t raise bees. That’s a new one. Nevertheless, I don’t think zombees will take out an entire hive. I had zombees several years ago, and they turned out to be more-or-less just a curiosity. They did not return the following year.

      In any case, be sure to put some of those light-seeking bees in a jar and see if zombie flies hatch out. Only then will you know for sure that you have them.

  • Wow, this is so sad. Last year I hived a feral colony from a neighbor’s chicken shed, discovered the nasty beetles, got those under control, then found a very slow growing colony, thought of a weak queen, thought will let her sort it out, fed and pampered them for several months, did not get strong as I would of thought, but from Canada here for winter and thinking they build up differently here didn’t think much of it.

    But I did notice the “at night attraction to the deck light” and in the morning swept them away, took the hive back to the original chicken house site, went back to Canada, got a distress call, “bees all gone, dead.”

    Visited with brother who also kept bees, asked “what is new with bees, he googled “Zombie Fly” and GOTCHAA came to mind, my night owl bees, returned and looked at the tool box that was the temp. stand, still had the little fly stuck to the syrup from feeding, I had put the tool box in a shed out of the sun, so now I picked up another feral in a electrical wire spool brought it home will “rehouse and see if they are “night owls” and report, to date find no log of their presence here. Has anyone found a source of remedial actions that people are discussing..??

    • John,

      As far as I know, zombie flies have not received much attention. It seems a strong colony can pretty much control them. I had them one year, but they have since disappeared.

  • We started finding dead bees under the light on our front porch. I went to zombeewatch.org and learned how to collect the dead bees and look for Apocephalus borealis. Sure enough, after several days the maggots came out and the pupae formed, etc. I sent them to California, and it was confirmed that they are the dreaded mite. I live in the mountains of North Carolina where it is very cool, so fortunately with a 60 day life cycle, we can only hatch out 2 to 3 cycles during our warm months. However, it seems to me that it is a problem that we can help with a little attention. Each bee hatched out about 4 larvae and pupae. I gathered about 50 dead bees, so I had about 200 pupae. After 60 days these would have become 200 flies that would have then laid 800 more eggs, killing 800 more bees and producing 3,200 larvae and pupae. The next cycle would have produced 12,800 mites. So by disposing of the 50 bees, I prevented an exponential spread of the mites. It is worth our while to learn, and make the light traps and dispose of all the infected bees we find. Sweeping them into the grass could turn a small problem into a huge one.

    • Claire,

      That sounds like the way I control wasps: catching the queens by hand. It can save a lot of trouble later. I think it’s commendable that you had them tested and confirmed.

      One note, however. Apocephalus borealis is a fly, not a mite. Mites are not insects and do not have a pupal stage. Because the zombie fly is an insect, it is very difficult to control inside a beehive.

  • Right! My mistake – a fly not a mite. Thanks! We did check inside the hive at the end of the summer and found no problem from Apocephalus borealis inside the hive. (There were, however, some wax moths. Yuck!) Dr. John Hafernik at zombeewatch.org thinks the foraging bees are paracitized outside the hive, and then they leave at night to find the light and so die outside the hive. How cool is that!

    • Claire,

      I haven’t talked to Dr. Hafernik in several years. Does he think the bees are getting parasitized while they are actually on flowers? That’s interesting.

  • Hi Rusty,

    Some years back, before I started keeping my “Dance Hall Girls”, my wife and I had some horses. As you know, horses aren’t smart enough for cleansing flights (Wow, the thought of that, landing on your car, would be bad!). So, we were “blessed” with copious amounts of flies. In an effort to thin those out, we bought some fly predators. They are tiny wasps, that do the same thing to flies. Thus wiping out the flies. They kind of worked.

    I wondered if the micro-flies are some other man made wonder cure, gone awry, then remembered you said they were natives.

    Maybe, they are creations of the “High Fructose Corn Pseudo Honey” industry.?

  • I had never heard of ZomBees until yesterday when a member of the local beekeeper FB group mentioned it. I have been seeing dead bees on the ground and wall below a porch light for a couple of weeks. I thought they were dying from poisoning or a paralysis virus. I was surprised to find some flying around at midnight a few days ago. Spiders near the porch light proved to be a convenient sampling device. The first captured bee I looked at had a fly and it’s pupa shell trapped in the silk the spider had wrapped around the bee. FWIW, I’m located in Eugene OR. I reported my discovery to the ZomBee network.

    • Gregory,

      I’m glad you noticed and happy that you reported it. I never saw them again after that one time, so I don’t think they are a large or long-term threat.

      • I turned off all of my porch and landscape lighting and set up a light trap. I’ve got a week’s worth of samples and have found maggots, pupa and flies in several jars already. The numbers have been increasing each night, with 40 last night. I’m watching the trap now and will easily catch more than 40 at this rate. I don’t think I have reason to be concerned until I’m seeing hundreds instead tens of zombies each night. I have an IR security camera point down at the entrance of one of my hives. I watched an infected bee sprinting in, out and on the hive and then fly off on its own earlier this evening. The other bees ignored it. Creepy.

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