The long and constant battle
The word Varroa strikes fear into the beekeeper! Long a threat not just to individual beehives but to the very survival of the honeybee, the Varroa Mite was first discovered in the early 1900’s. It has now spread to most of the rest of the world, with a notable exception being Australia.
The first Varroa in the US were discovered in 1987 and, since then, they have had a direct and major impact on bee populations across the country. Today, they are accepted to be a part of the beekeeping landscape, albeit reluctantly.
With this long history, the Varroa mite is no longer a surprise. Indeed, the US beekeeper should accept that his or her colonies will almost certainly encounter Varroa at some point.
In fact, “my colony has Varroa!” is not, in itself, the death sentence that many beekeepers consider it to be. Huge numbers of colonies survive just fine with Varroa present. Why? Because they haven’t yet reached the tipping point at which the bees can no longer control the number of Varroa. Before that point, bees have the smarts to fight back, as we’ll see below!
The real issue is not so much “if” – but “when” and “how many”.
The Sneaky (and Effective) Life of the Varroa
As beekeepers, our love and passion for the honey bee is well documented. A large part of this springs from our amazement at how bees live their lives, particularly in the collaborative society they build. At every stage of the ebb and flow of the colony, something happens that we find fascinating.
And yet, despite our inclination not to look upon the tiny Varroa mite with such favor, it also has a wondrous story. Although the end result is far from what we – or our bees – would like to see, the Varroa is a devilishly sneaky creature. We will look at this in future articles, but be aware the Varroa is pretty amazing too – unfortunately for our bees and beekeepers!
Among the many aspects of the Varroa life cycle, their life within the confines of a capped cell is where the most damaging action takes place!
Let’s take the example of a mated Varroa mite. She may have hitched a ride on a bee, often from a far-away flower on which the bee landed for a brief period. This is a prime example of how Varroa can spread so quickly across a wide area.
When the bee arrives back at the hive, the Varroa mite will wait for the right time. She’s looking for an uncapped with larva, preferably about a day from being capped. She will hide deep in the cell, until she is confined in a capped cell – with just one juicy larva for company!
From that point, “bad stuff” happens. Again, we will be looking more closely at these events soon, but let’s skip to the end result. In short, that one female, mated Varroa mite will lay eggs and they will hatch.
How many eggs? Well, this is key and is our focus here.
In a capped cell housing a worker bee, she will lay 2 eggs on average. In a drone cell, she will average 4.
Why is that important? See below.
Deploying Drones To Fight Varroa
More Drone Cells, Not Less?
So what can the beekeeper do to combat this threat? There are many ways to approach this. But one natural option we can use leverages the Varroa mites own behaviors and preferences as a mechanism to fight back.
As we saw, the female Varroa mite will average 4 eggs in a drone cell. The reason is rather straightforward – space. The drone cell is larger than the worker cell and can also be easily distinguished by the domed cap. This is an invitation to the Varroa!
So, with that, the last thing you want is to encourage the use of drone cells in the colony, right? Well, maybe not…
The use of drone cells is a useful tactic in the beekeepers toolkit! Varroa are attracted to the more spacious dimensions of the drone cell and can also be more prolific in terms of reproduction.
How can it help your bees by encouraging the use of drone cells? By using them as a “deadly attraction”. Here’s how.
Drone Frames As a Deadly Varroa Magnet
First, purchase one or more drone cell frames. This is a frame with cells imprinted that adhere to the larger dimensions of the drone cell. Once your bees have built out the comb on this frame, the queen will scoot around the frame intentionally not fertilizing the eggs she lays, since she knows to create drones in these larger cells.
And there is your “Varroa magnet”. Varroa will eagerly infest this frame of drone cells, with an average of 4 eggs in each cell in which a mated Varroa lays her eggs. That is a pretty concentrate area of Varroa within your colony. And that is your opportunity!
After the cells are capped, remove the frame, pop it in the freezer and soon everything on that frame (drone larvae and Varroa, both encased in cells) will be killed.
Then, just uncap the cells and place back in your hive. Your bees will clean up the mess, removing the dead drones and Varroa. They will then start the cycle over again, by creating beautifully formed comb and waiting for the queen to lay drone eggs all over again.
Perhaps we need to replace the saying “like a red flag to a bull” with “like a drone cell to a Varroa”!
A Curiosity About VHS Bees
The existence of Varroa Hygiene Sensitive (VSH) bees is well-established. Again, this will be something we will cover in greater detail elsewhere but, of their various Varroa-attacking behaviors, one also favors the use of drone cells.
VSH bees have an ability and a tendency to hunt down and Varroa mites – while they are in capped cells. They break into these cells and remove the pupa and the Varroa too. This is a pretty remarkable skill. Further, in ways we don’t fully understand, they have a preference to do this with drone cells more readily than worker cells. As such, VSH bees are more effective themselves at locating and removing Varroa from drone cells.
And that’s another reason why the tactical use of drone frames can be so effective.
