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My zombie flies: pets I could do without

My plan was to split my largest hive before I left town for a week. Although my husband was willing to deal with a swarm if necessary, I decided it was better to save him the trouble.

Before I could begin, I had to prepare a place to put the split. I decided on my one dead-out, a hive where the colony had perished suddenly in March. It is embarrassing to say that the hive starved, but I’m sure that is what happened. I had been feeding all my colonies once every two weeks since the unseasonably warm weather arrived, but while that worked for my other hives, this one didn’t make it. It was fine on March 4, but by the time I opened it for the next feeding on March 16, there wasn’t a speck of food left and everyone was dead.

As soon as I found the colony dead, I closed up the hive so predators couldn’t get in. Otherwise, it sat there unattended until April 25 when I decided to clean it up and use it for the split.

I began scraping the tops of the frames in the highest of the three brood boxes. I saw some funny-looking cocoon-like things sprinkled around the bars, but I just scraped them into the grass. Something, though, bothered me about them. After a few minutes I stopped what I was doing and looked for more. They were easy to spot since there were so many. It occurred to me that they looked like the photos of zombie fly pupae I’d seen on the ZomBeeWatch.org website. I decided to collect some and take photos.

The most frustrating thing was trying to upload my findings to ZomBeeWatch. Their data collection software wasn’t set up for finding pupae in a dead hive on dead bees in winter not near a light source. Irritated, I sent an e-mail to the contact person and asked what to do.

In the meantime I finished cleaning the hive. The only place I found the fly pupae was near the dead cluster of bees in the top of the top brood box. I searched in the two lower boxes and I sifted through the debris on the bottom board, but found no more pupae.

A few hours later, I received an fascinating e-mail from John Hafernik of San Francisco State University. John is the person who first discovered that the parasite, Apocephalus borealis, had begun infecting honey bees. In his e-mail he said he had forwarded my photo onto Brian Brown at the Natural History Museum of Los Angeles County. He said that both he and Brian believed my sample looked like A. borealis pupae. He said that if that were true, it would be the very first evidence of the fly overwintering in a failed honey bee hive. He asked me to keep the pupae isolated and watch what happens. Nothing like being famous for all the wrong reasons.

I put everything in a mason jar and asked my husband to watch it while I was gone. Yeah, I know—instead of worrying about swarms, he now had to worry about parasitic flies instead.

During a conversation with John, he asked me to say hello to Ramesh Sagili, Assistant Professor of Horticulture, at the Oregon State University Honey Bee Lab. This turned into an opportunity for me to see confirmed samples of A. borealis pupae as well as an adult fly—something that has been very helpful.

Now that I’m home again, I have mason jars lined up containing all manner of zombie flies. On Sunday May 5, I got my first adult fly, on Monday I got another, on Tuesday three more, and three so far today. I’m operating a regular zombie fly hatchery in my kitchen. Right next to dinner I have jars of dead bees, jars of pupae, jars containing flies of various ages, and jars of dead flies, too.

I still need to submit photos of my adult flies for the final confirmation of their identity. This is turning into a nightmare; I’ve taken dozens of photos where you can’t see much. I’m probably going to end up sending the dead flies to OSU and let them work it out.

Still, it’s been a fascinating ride. Yesterday I posted a question and answer page about zombees and zombie flies, and I urge everyone—especially beekeepers—to get involved with ZomBeeWatch.org and help gather information about this little-known threat to honey bee health. I signed up almost a year ago and never expected to see a zombie fly in my entire life. Now I’m raising them in my kitchen. You never now where those small acts will lead.

Rusty
HoneyBeeSuite

Possible zombie flies hatching in mason jars.
Possible zombie flies hatching in mason jars.

Mites on a bumble bee

Yesterday I spent some time deleting photo files from my computer. I was just about to trash this one when I saw two odd-looking dots on the back of the bumble bee. When I enlarged it, I decided the dots looked like mites. If I had noticed them at the time, I would have tried for a better shot. Instead, this is what I have:

Two mites on the thorax of a bumble bee. Photo taken June 2012 near Olympia.
Two mites on the thorax of a bumble bee. Photo taken June 2012 near Olympia.

It turns out these mites are not uncommon. They are most likely in the genus Parasitellus and can be seen singly or in large groups on the thorax of bumble bees.

From what I’ve pieced together, these mites live in the nests of bumble bees and disperse by hitching a ride on foraging bees, preferably queens. The phoretic stage seen in the photo is a deutonymph—one of the larval stages—not a mature adult.

The mites spread when robber bees or cuckoo bees enter the nest, when deutonymphs are left on a flower and hitch a ride on a different bee, or when the mites simply switch from one bee to another. Occasionally they are found in the borrows of small animals and even in honey bee hives, where they do not survive.

It is unclear if the mites do any harm to the bumble bee. In fact, some sources suggested the mites may be predatory on other mites and thus be beneficial to bumble bee colony health.

Rusty
HoneyBeeSuite

Varroa mites feeding on a sick bee

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!

Two Varroa on a honey bee with deformed wing virus.
Two Varroa on a honey bee with deformed wing virus.

Zombees arrive in Washington

It’s ironic that just two weeks ago I signed up with ZombeeWatch.org, intending to set up a light trap and send my results, positive or negative,  into the database. I just had a feeling the parasite would be here because we are not that far from California and Oregon, places with known Zombees. Sure enough, an article in today’s Seattle Times reports the first confirmed case of Zombees in Washington, in a town about 55 miles north of where I live.

I first wrote about the parasitic fly, Apocephalus borealis, back in January (A fly in the hive causes bees to flee) but after that I didn’t hear much about them until one of my readers on the east coast wrote last month, asking if there was anything thing else that would cause honey bees to be attracted to light. While looking for an answer, I got interested in the phorid flies again and joined ZombeeWatch.

I have no particular reason to think I have a problem with the flies, but I thought it would be interesting to set up a trap. I don’t normally run exterior lights at night so unless I deliberately set up a light trap, I would probably never notice bees at a light source.

My hunch—at that’s all it is—is that the parasitic flies are widespread and much more common that anyone suspects. Since they are a native species that preys on bumble bees and certain wasps, I suspect they more-or-less follow the distribution of those species. The big unknown is whether the flies have always affected honey bees or if they have recently evolved to parasitize them. And, of course, if it is a recent change, how bad will it get?

The article about the first Washington case can be found here: “State’s first case of ‘zombie bees’ reported in Kent.” You can join ZombeeWatch.org—or just learn more about the so-called scuttle flies—on their website.

If you are unfamiliar with this parasite, the small adult fly lands on the back of a bee and injects its ovipositor into the bee’s abdomen. It lays eggs there which eventually hatch into larvae and feed on the inside of the bee. The bees become increasingly agitated and, at some point, become attracted to light. They fly from the hive at night and hover around a light source until they die. After the bees die, the larvae crawl from the bee’s body and pupate into something the size and shape of a grain of rice. New adult flies emerge from the pupae several weeks later.

Rusty
HoneyBeeSuite

A fight with the varroa mite in New Zealand

Varroa destructor hit the North Island first. It established around Auckland and spread gradually south. At first, beekeepers negotiated quarantine lines. Some apiaries were split down the middle, and boundaries had to be renegotiated every time the infestation spread. And in the meantime, an infested feral colony rode a hollow log into Wellington and Frank’s bees became the first in the area with Varroa.

Frank did not shy from the “bad beekeeping” stigma that encourages beekeepers to under-report cases like this. Instead, he worked to contain the infestation. He marked a five-mile radius around the Varroa hive, determined to destroy neighboring colonies to prevent Varroa from spreading. Frank climbed fences, turned ankles, and plugged and poisoned the wild beehives inside his quarantine zone. He offered honey to people who could point him towards feral colonies. He even managed to poison a nearby beekeeper’s unregistered hives—by mistake, of course—he had thought they were abandoned.

Frank got most of the ferals. All but one colony, actually, because it was on private property and the owners would not grant him access. So Varroa proliferated in the Wellington area, expanding outwards as the northern population spread south. The quarantine was a losing battle, Frank says.

That’s part of what makes Frank’s effort so admirable. Facing an impossible task, he refused to give up. These days, in anticipation of miticide resistance, he is exploring alternative Varroa treatments. In order to monitor mite levels, Frank  “fogs” his hives with vaporized food-grade mineral oil (FGMO) using a small flamethrower. He shows me how to pump a few puffs into the front entrance of each hive and warns me not to place the fogger too close. The popcorn sound is bees cooking, he says. Overall, casualties are relatively low. Frank estimates that we’re singeing the wings of approximately twenty bees per hive. After fogging the first apiary, I am red-faced and dizzy. Frank mentions that a dusk-mask would be advisable.

The fog agitates the mites, providing a one-day knock down, but it does not kill them. We collect the mite fall on slide-out “sticky boards” on the floor of each hive. These help us determine whether to implement a follow-up cord treatment. The short cotton cords are soaked in a solution of equal parts honey (or sugar syrup), food-grade mineral oil, and beeswax, adding 5% thymol for extra effect. Once dry, they are placed on top of the frames, two cords per brood box. The honey attracts the bees to the cords, and the FGMO kills the mites. Frank treats with cords about once a month, as needed.

These techniques were developed by Dr. Pedro Rodriguez of the United States, but Frank is experimenting with them himself to determine which treatments work best for his bees. It’s extra work for uncertain payoff. That’s some admirable beekeeping.

Maggie
HoneyBeeSuite

Frank uses a wide-tooth shearing comb to check drone brood for mites.
Frank uses a wide-tooth shearing comb to check drone brood for mites.
Fogging the hives with food grade mineral oil.
Fogging the hives with food grade mineral oil.
Cotton cord soaked in honey, mineral oil, beeswax, and thymol.
Cotton cord soaked in honey, mineral oil, beeswax, and thymol.