Minnesota Hygienic Queens and Varroa Control

I’ve been experimenting with different Integrated Pest Management approaches to controlling Varroa. I started using Oxalic Acid last year, and it’s pretty effective, but it has limitations.

Last month I tried creating an artificial brood break by caging the queen with a large push-in cage. The queens were supposed to stay confined for 12 days. The bees released them in 3 by removing the wax around the edges of the cage. So much for that idea.

Next I’m trying a strain of Italian bees that have been bred to be resistant. Minnesota Hygienics are not only supposed to be better at grooming and removing Varroa on bees in the hives (phoretic mites), they are also supposed to be able to detect when a Varroa is in a cell and removes the pupa infected.

I picked up three of these queens yesterday. I had already prepared the hives last week by removing the queens. This would give the hives a real brood break before the new queens were introduced. And I did a sugar roll to assess the mite levels before introducing the new queens so I can compare their effectiveness against Varroa.

However, when I opened the first hive, I found not only were there no emergency queen cells started, but there were eggs and tiny larvae present. I know I removed the queen, so how could there be eggs and larvae?

I got my magnifying glass to see if the eggs were centered and single. I really hoped I didn’t have a laying-worker hive in which a worker bee tries to lay eggs. No good could come from that. However, the eggs were centered in the cells and there was only one in each. So began the search for a laying queen.

Fortunately I found her pretty quickly and removed her. The hive will need at least a few hours to know she’s gone for sure, then I can introduce the new queen.

But the question remains: where did this queen come from? There’s been no evidence of supercedure, as I had recently checked that hive. I feel confident they didn’t start a queen before I removed their old one.

And they couldn’t have raised a new queen in the time since I removed their old queen. It’s only been 10 days. It takes 16-18 days for a queen to emerge and at least a week, usually longer, for her to mature and take her mating flights.

So, my best guess is a usurpation swarm. This is a small swarm of bees looking for a hive to invade. They sneak in a few at a time, kill the queen, and usher in their own. If one of these swarms happened by and discovered the hive was already queenless, that would be a bonus because they wouldn’t even have to remove an existing queen.

Whatever the case, I removed this mystery queen and will put in my new queen later today.

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