diseases parasites varroa mites

Varroa mites feeding on a sick honey bee

Two varroa mites feeding on a sick honey bee with deformed wing virus.

Rebecca Wilson, a beekeeper in southwestern Florida, sent me this photo of a honey bee crippled with deformed wing virus (DWV) and saddled with two Varroa mites. There were actually three mites to start with, but one fell off before she got a photo. I think the scene is heartbreaking and morbidly fascinating at the same time. And for those who’ve never seen mites or DWV, it’s a great illustration. Varroa mites carry deformed wing virus from bee to bee, transmitting it through their bite.

Rebecca writes:

Some of us from the association were out at the club apiary last Sunday to apply mite treatments (gotta love the schedule in SWFL!) and we knew one of our hives definitely had mites. A new beekeeper that I am mentoring was with us, and I spotted this bee on the side of that hive, noticing the deformed wing virus right away, and plucked her up to show to my mentoree . . . and three mites were on her! I managed to get a few photos. While I was holding the poor bee to grab my camera, one of the mites climbed off her onto my glove. Eww!

Discover more from Honey Bee Suite

Subscribe to get the latest posts to your email.


  • Poor little bee. Considering how small a bee is, those mites must weigh heavy? I wonder if foragers carrying a mite would have reduced nectar carrying ability.

  • I think the weight is likely not an issue in terms of carrying a few mites around…I am thinking that bees are not only over-engineered for their purpose as an evolutionary margin of error, but how much do the tracking transceivers scientists use weigh? Just guesstimating about the same?

    Is the big impact the damage they do as the bee pupates? Virus transmission and weakening by feeding off hemolymph?

    • It’s an interesting subject, however. I have read about the maximum loads honey bees can carry, but I don’t remember where. I will look for it. With Varroa, it’s not only weight but drag; bees are not as aerodynamically efficient with those bumps on their back. Still, as you point out, the major damage caused by mites is to bee (and colony) health.

      • Hi Rusty,

        I’ve read in one of my bee books that bees can carry a maximum of 100mg (their own body weight), but average foraging loads are 30-50mg of nectar, 16mg (8mg x 2 pollen baskets) or 25mg of water.

        I agree, the viruses transmitted via mites are the main problem, but I remember going to a talk by a bee inspector where he mentioned that the weight of the mites is a burden to the bees.

        • Thanks for those numbers, Emily. Now I’d like to know how much the transmitter weighs and how much a mite weighs. The numbers seem small, but not in terms of percentages. If a 50mg load of nectar is half a bee’s body weight, imagine a 50-kilogram person carrying around a 25-kilogram sack . . . nearly impossible to walk, let alone fly. Yes, bees have evolved to do this, but at some point they expend more energy foraging than is contained in the food they bring home. This is the reason bees foraging on warmish winter days can be a drain on hive resources. But I digress . . .

  • Colonies have been found with DWV and no varroa. It is now confirmed that DWV is as common as flu virus in humans. Most of these viruses are present in even the most isolated colonies without varroa, including Australia. We are now understanding that most ailments are ever present and just waiting for colony health to decline enough to ravage through and collapse bee colonies. I am now more convinced than ever that colonies must be watched closely and selected for vigorous brood culling abilities which are certain to be seen in very early spring or late fall. By watching at the entrances, we can see if our colonies exhibit this very vital behavior without even opening the hive. Since there is no known way to help our bees become “immune” to any of these viruses, beekeepers must rely on their best judgement and replicate their strongest colonies by making splits in spring or early summer while the local nectar flows are strong. Any strong colony can even easily be split after the honey harvest, but before the summer dearth. At this time there are plenty of resources still available for colonies to successfully raise and mate new queens to further any apiary, without any additional intervention. By splitting we also ensure the new split colony will have a very small, if any, infestation of varroa.

    • Just a note about deformed wing virus . . . Bill is correct that the virus is commonly found in bee colonies. But the virus doesn’t generally move from bee to bee unless it is injected into the hemolymph—something the Varroa mite is adept at doing. So while the virus occasionally infects bees in Varroa-free colonies, it is usually isolated to just a few bees that may have acquired it through a wound, for example.

      As a point of comparison, both malaria and bubonic plaque behave similarly in humans. Although the diseases can occasionally be transmitted without insect vectors—such as with blood-to-blood contact, contact with infected tissues, or inhalation—it is much more likely to be spread by the bite of a mosquito in the case of malaria or a rodent flea in the case of the bubonic plague. In the process of accessing blood, the insect vector injects the pathogens into the blood of the human—or into the hemolymph of a bee.

  • This image reminded me what I did as a new beekeeper, just out of curiosity: snapping images of each frame during inspections and enlarging them on screen. All I wanted was closeups of bees doing whatever they did. Actually seeing the queen, and newly laid eggs in the cells around her, was a thrill. Then I spotted mites! Lots of them! I had already seen some deformed wings and read up about Varroa.

    Happy to say that powdered sugar dusting seems to have been effective: I haven’t seen any more deformed wings. The hive is now a full deep and medium, so I can’t snap every frame as when there were only 4 total. But a sampling has turned up no mites since June.

    A small hand-held like my Nikon Coolpix is all the camera you need for this, and I modestly recommend one as part of your equipment. And maybe a once- or twice-a-season all-frames shoot and closeup review.

    • Mine is a Canon Powershot. I have a very nice DSLR with macro lenses, but the Powershot is what I take to the bee yard unless I’m going for something specific. My husband actually bought it for me for just that purpose, he made sure to find a point and shoot that had great macro capability so I could chuck in the pocket of my suit!

      And I agree with you about beginners shooting the frames, it is a great way to have extra time to see things that you might have missed when you were actually in the hive. One of the new beekeepers I am mentoring does it so she can send me inspection photos when she goes in on her own, in case I see something she didn’t!

      • Thanks Rebecca: if I upgrade I will look at the Canon, just because this Coolpix is limited on stuff like Zoom. Then I would give it to one of the younger beekeepers. My mentor kept saying, Look, look, eggs! and I couldn’t see them para nada, till I caught the queen in one shot.

        I bring my laptop to meetings, and they love the closeup images. But they’re all like, I’m this huge techie, which is totally ironic. Our club voted me its Media Coordinator, just cause I offered to send email notices and make them a Facebook page. Still hardly any of them will post on it.

        Anyway, as an aid for mite, hive beetle & wax moth control, it’s worth every bit of the trouble. Bless your mentoring work!

        • Thanks, Nan!

          I love mentoring. I probably spend a lot more time mentoring these days than I do working my own bees, even though I’m trying to expand. I had a great mentor when I started, but he wasn’t available too often, and when I got a really hands-on mentor later, I realized what I was missing, and because of that, I make myself as available as I can to the new beekeepers in the club. I’ve been trying to write a blog post on mentoring, it’s been eluding me for some reason.

          You sound like me! I’m VP now, for my second term, I’ve done the newsletter since I joined, and I started a forum for us but no one uses it much yet. But hey, I’m helping new beeks, and that’s what’s important to me.


  • I have been doing the bee thing for a couple of years and this the very first time for me to see what a mite looks like…!
    Kudos ….. What a great instructional photo..!

  • Hi Rusty and fellow beekeepers,

    I am a first year beekeeper in SW Illinois, 15 mi. from St Louis, MO. Our apiary is located in the Community Garden and has one beehive.

    I noted a small number of mites on our sticky board at the end of the honey flow season last fall. I did two powdered sugar applications on our hive before cold weather set in and did not see any additional mites dropping onto our sticky boards after those treatments.

    We added a 14 lb. bee candy feeder and a winter “blanket box” to aid in hive moisture control.

    When should I reinspect the hive? I know leaving the hive unopened in the cold winter months is beneficial to the bee colony. Is there a right time to check for mites and/or treat for them before spring brood hatch and forager bees begin to take flight in search of spring’s first pollen?

    • Jim,

      If your bees were ready for winter, and it sounds like they were, I wouldn’t do much until early spring. I sometimes like to tap the hive gently just to make sure they are still there (although this is more for me than for them). If you have a warm day, you can check their sugar supply and make sure they have plenty left. If mite counts are high, you will want to treat beginning in early spring. Remember that powdered sugar must be sprinkled weekly on all sides of all brood frames to be effective long term. If it is cold, you can use a bellows and pump it in from the hive entrance without opening the lid.

  • I have three hives and I just found out that two of them look infected with DWV. What are my options for treatment if any. Please help not sure how to handle this.

    • Mel,

      As you know, once the deformed wings start showing up, the virus has spread throughout the colony. All you can do is treat for mites with any of the currently available methods, and then hope for the best. Take good care of that third colony because infected bees will drift into it from your sick colonies.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.