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​MESSING WITH POWDERED SUGAR: Mid-Summer Dusting Results

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The blackberry flowers in our area, Grass Valley, California. all seemed to turn to berries on the same day, June 26. June 25th, it seemed we had lots of flowers, June 26, the flow was over.

And suddenly my husband noticed “my” bees swarming “his” hummingbird feeders. Didn't matter we have a commercial apiary less than a mile away. But I thought, if it was my bees, I should feed. We were still a few weeks away from the star thistle blooming.

It was the right time to do a powdered sugar dusting, right after the blackberry flow and as luck would have it, I was able to find the queen in the first hive and did a powdered sugar shake. 8 mites. 2 mites higher than the recommended threshold. I dusted that hive with powdered sugar, waited 20 minutes and dumped the results into a pail of water. 91 mites. That’s on the high side. I like to see less than 60 mites in the water. The next two hives were in the 40’s.

Hive #4 lost a queen. I put in a queen cell from another hive on June 6th. This would be a typical Brood Break to reduce Mite Loads. No queen since at least June 1st and the new queen would have hatched and been mated by the 20th. All mites in the hive would have been phoretic (outside of the bee cells). That dusting dropped 423 mites in 20 minutes. Pretty impressive. Since I remove the observation board after the initial 20 minutes, additional mites drop below the screen onto the ground to be taken away by ants. You can expect a severe mite drop for the next couple of hours after the initial dusting.

Randy Oliver has a great chart (at bottom titled “Mite Population” that shows if you do no treatments for the year, by the beginning of July you could have 2000 mites and if you continue not to treat, by the end of August you could have 8000 mites. If you dust monthly, by July 5, you would have under 1000 mites. My dusting schedule is different from his chart. I dusted 3 weeks in March and then once time in May, just to see. My counts were low on both sessions.

With Hive #4 loaded with phoretic mites, I might have taken around half of the mites down in the first 20 minutes. In any case, I’m keeping that mite load low.

I fed the 4 hives with heavy syrup and took down all the hummingbird feeders. We put them back up in the late afternoon and then took them back down in the morning. The hummers are on it at dusk and dawn. We did that for a week or so till we saw no more bee activity.

A few hours later I went down to the bees only to find extreme robbing going on in my weakest hive #3. I put on entrance reducers. When things quieted down, I opened #3 and was happy to see no damage (robbing will show jagged uncapping to get at the honey). The mite count shot up to 181 mites which shows how robbing can distributes mites to other hives.

My neighbor called and said she was seeing extreme robbing on her hives. I called Randy who confirmed robbing going on in all his yards. He said the smell of spilled syrup will cause these frenzies. And Powdered Sugar doesn’t have a smell, so that’s why I was able to dust without a problem.

I sent Randy my article (Thanks Randy) to check it out and he said,

There is one thing that you should make clear--that dusting is truly efficacious only under three scenarios:

  1. It's performed at least once or twice a month over the entire course of the year, or
  2. It's performed during a natural or induced brood break, when there is no sealed brood in the hive, or
  3. If the colony contains brood, that it's repeated at 4-day intervals at least 4 times in a row.”

Randy is the expert on this. I do want to share my experiences since 2005.

On point #1, we keep our mite loads low dusting for 3 weeks, twice a week if counts are high (over 60 in the water) at the end of March, end of June and second week in September. We developed that schedule around the honey flows as I was worried about contaminating honey we were selling to the Briarpatch. We also dust once a month after October to February when we have lower amounts of brood. If I see a spike, I will dust again in 3 or 4 days and keep watching till it drops. Point#2, YES, the brood break works, see Hive #4 info! You knock down a bunch of mites. And point #3, Yes, if you dust every 4 days for 3 weeks, you knock down that many more mites. Especially important if your count is high. If I see under 60 mites, I will dust every 7 days for 3 weeks. If I see under 20 mites in all of our hives, I might just stop dusting. If one hive has high counts, I’ll dust all of them.

I want to show off my latest chart. It’s cool, you can see the high count of phoretic mites in hive #4 drop dramatically has I continued to dust during my 3-week period. You can see the mite count go up on the hive that was being robbed and then drop down again with repeated dustings. Notice that I dusted 3 times in a little over 3 weeks.


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