bees in the news parasites

A fly in the hive causes bees to flee

A small parasitic fly, Apocephalus borealis, may turn out to be one player in the failing health of honey bee colonies in North America. The parasite, a type of phorid fly, has long been known to parasitize bumble bees and paper wasps, but recent research shows that it may also attack honey bees.

In an article published yesterday in the journal PLoSOne, researchers explain that the tiny adult female fly lands on a honey bee abdomen and lays eggs by placing her ovipositor into the bee. The entire process takes two to four seconds. Seven days later the adult phorid larvae emerge from the area between the bee’s head and thorax. One to thirteen larvae emerge and leave the dead bee behind. The larvae then pupate elsewhere.

Oddly, honey bees parasitized by the phorid flies are attracted to light. Individuals are found to abandon their hives at night and fly toward sources of light where they remain until they die. In fact, it was large numbers of dead honey bees around lights on the campus at San Francisco State University that lead to the discovery of phorid fly activity in honey bees. Also of interest is the fact that many of the phorid flies were found to test positive for Nosema ceranae and deformed wing virus—pathogens often associated with dead colonies.

The authors of the paper speculate that the native phorid fly has recently evolved to accept the non-native honey bee as a host. If the fly had long been a parasite of honey bees, adult phorid flies, their larvae, or accumulations of dead bees around lights would have been noticed before now. As they point out, the honey bee is one of the most studied creatures on earth so it is doubtful this fly would have escaped detection.

If the fly has indeed shifted hosts, it is bad news for beekeepers. Unlike bumble bees and paper wasps—creatures without huge populations—a honey bee colony can provide a vast breeding ground for the flies. And at one to thirteen larvae per bee, it wouldn’t take long for the flies to overwhelm a colony. Furthermore, this tremendous population of flies could leave the hive and harm bumble bees and perhaps other wild bees as well. Scary stuff, great material for horror flicks.

I urge you to click on the link to the original article and enlarge the photo of a phorid larva leaving a bee. For more details on this phorid fly, see Zombee Questions and Answers.



  • Like the article about the flies in the hive. Found it very interesting but cannot access the pictures. Also liked the one about carrot honey. Don’t suppose if I grew a large bed of carrots in front of my hives on my allotment I would get carrot honey. I will post some pictures of my hives on my allotment when I have finished making my new hives.

  • I’m a new beekeeper and I do have 1 or 2 honey bees flying around my porch light occasionally at night. So my question is, do honey bees exhibit this behavior even if the have not been parasitized?

    • Hi Diana,

      Most flying insects display some degree of phototaxis, which is simply an attraction to light. If you trap some honey bees in a dark room, for example, they will fly toward the windows or the skylights. However, normally honey bees stay in their hives at night, so we don’t see them going for light very often.

      However, displaced bees or lost bees will be drawn toward light sources. So in your case, the bees could simply be ones that are lost. Perhaps they were blown off course from the wind, or suffered displacement somehow. Perhaps their hive was being moved and they got out, or they were trapped in a car. For whatever reason, they were not where they should be at nightfall, so they were attracted to a light.

      It is my understanding that something similar happens with the zombees. They leave the hive willingly in order to prevent the spread of infection in the hive, a behavior well-documented in honey bees. But once outside, they have no where to go and end up be attracted to light. Ultimately they die, often near the light source.

      So just seeing bees near a light source does not mean they are infected with zombees, although they could be. That is why when bees are found at a source, the bodies are kept a jar for a period of time to see if the zombee larvae come out. That is the clear proof of infection.

      Interestingly, I had a case of zombees several years ago, only I discovered the larvae in a dead-out hive and recognized them and sent them in for analysis. It seemed to be an isolated case, and I never saw any more after that one incidence.

  • Hi,

    Bad smell comes from my hive and every evening bees are fighting fruit flies…it does not seem to be catastrophic but it is an issue. We think one of the frames contains some bad wax/fermented honey or some similar combination. These bees are from a swarm and their old combs are still there. The problem is that they have interconnected 9 frames which cannot be separated now…which was my fault. When I brought them, I did not put 10 frames – only 9. Now the only way to troubleshoot the bed smell is to separate the frames which will be quite messy…and I am procrastinating.

    Any tips on safe separation of frames? Fruit flies?


    • Dragan,

      A bad smell would have me worried about American foulbrood disease (AFB). It’s interesting that one of the main reasons for using removable combs is so the beekeeper can easily inspect the hive for AFB. But if the frames are all glued together, the problem can’t be diagnosed. So, my opinion is that you need to separate those frames and figure out what is going on inside your hive, as soon as possible. Just take a sharp knife and do it. I don’t think the fruit flies are a problem. If the cells are leaking honey, they may just be attracted to the scent.

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