Learn about the varroa mite and how they can quickly destroy a honey bee colony. Learn how to take a mite count, as well as how and when to treat them in the fall and spring.
If you need to brush up on our other articles related to Beekeeping, please check out our posts:
- Terminology you should know about beekeeping
- Terminology you should know about beekeeping – Part 2
- How to start beekeeping
- How to start beekeeping for beginners
- How to make a split and install a queen
- How to clean up beehives in the spring, how and what to feed bees in the spring
If you’re just starting beekeeping, you may want to check out our post on Logistics you must know in order to start beekeeping
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Why is the varroa mite a problem for honey bees
Varroa mites are a common pest for beekeepers to deal with. Here’s the shortened version about varroa mites so you can begin to understand more about this nasty little critter that are wreaking havoc against honey bees globally. Think of the varroa mite sort of like a tick that feeds only on honey bees. They feed on the fat body of the honey bees. The females are especially tricky, that have dirty, dirty mouths that transmit viruses (she should clean it up with Orbit-anyone remember those commercials?!).
The females can live in a capped honey bee brood cell for multiple days, where they will lay their eggs. Once the varroa eggs hatch, the mites feed on the immature honey bee larva/pupae. This likely will cause the bee to have a thing called Deformed Wing Virus, or DWV, or a number of other viruses. In Deformed Wing Virus the wings on the honey bee are small, and blatantly.. deformed…tattered looking, meaning that the bees with the DWV cannot fly easily.
If a bee cannot fly well, they cannot find food. If they cannot find food then they starve, and so do the new bees in the colony. If that bee is taken out of the process of the colony function, then the rest of the colony goes downhill, and will eventually die.
How do varroa mites multiply in a honey bee colony
Now, let’s think a bit more “big picture.” The biggest problem, in my opinion, is the sneakiness of the female varroa mites (those b!tches!). The female will crawl into a honey bee larvae cell, just before it gets capped. Once inside of the capped cell, she is free to go about her business. She is completely protected! Bees historically will not uncap a cell after it’s been capped because they know there is a baby bee (brood) inside.
The female varroa mite will eat into the fat body of the honey bee. This is where viruses are passed among the honey bees. This is also the spot where she will lay her eggs. She will continue to eat at the honey bee for the roughly twelve days a worker bees is capped, and 14 days a drone cell is capped. Check out our video here of a varroa mite on some drone brood between deep boxes.
Why female varroa mites are so destructive
When the female mite lays eggs she always lays a male varroa mite first, then it is followed by female(s). In each cell, those baby varroa mites mate with each other, and then they emerge when the honey bee hatches. One to two mated females will emerge from a worker honey bee cell. Two to three mated females will emerge from a drone honey bee cell. Varroa mites typically prefer the drone brood cells. There is more room, and they have more time to get busy.
After that the mites hitch a ride on the nurse bees that are overseeing the brood nest. The newly bred females will drop into new cells and multiply again in the same fashion. Varroa mites can double their population every 22 days. If the honey bees are left untreated to take care of some of the varroa mite population the varroa mites will continue to reproduce in a way that creates weakened bees, over and over again. The weakened bees will eventually turn into dead bees, and then the hive will ultimately die.
How and when to treat honey bees for varroa mites
As a beekeeper, you have a few different options to treat varroa mites…you could take away the varroa mites’ food source (the honey bee) or their shelter (the beehive), or apply a chemical to treat some of the population of varroa. Considering that you WANT to raise honey bees, taking away the honeybee isn’t possible, and taking away the varroa mites’ home isn’t possible, without destroying the baby bees (brood) underneath.
Therefore, you must find a way to manage and treat the varroa mite. This video, Life cycle of varroa mites and their effect on honey bee colonies, from NOD Apiary Products shows a pretty good example of how the varroa mite interacts with the honey bees. It shows how the varroa mite, if left untreated, can run rampant and take over a honey bee hive very quickly.
Ways you may be able to naturally manage varroa mites:
- Selectively breed for more mite resistant bees
- Some bee breeds, or hybrids of bees are more naturally resistant to bees. Science isn’t exactly clear why this is the case..do they do a better job of cleaning themselves (ie-hygenic), or do they do something in the hive to get rid of the mites? Hard to say. However, if you find a bee breeder that is consistently coming up with varroa mite counts of five or less in the fall and spring, they are onto something good!
- I have read studies that say having hops around the hives can help. You know, hops that are used to brew beer with. Supposedly this is because of the beta acids in hops that deters the varroa mites. Now, I haven’t gotten the chance to experiment with this first hand, but hey…it might be worth a shot…and you might be able to brew a few beers with it!
- Some reports say that the herbs thyme, savory and spearmint have acaricidal properties (pesticide to kills ticks and mites) that could be effective in controlling varroa populations according to this article from PubMed
Most common way beekeepers manage varroa mites
Most beekeepers opt for the treatment of varroa mites. Pretty much everyone that is a responsible beekeeper will want to learn the steps to determine their mite count, and then plan a treatment approach accordingly. Let’s dive into the steps of getting a mite count, and learn about when to treat varroa mites.
How to get a mite count
In order to get a mite count you need about half of a cup of bees and some way for the varroa mite to release from the honey bees. You don’t need special equipment, however, if you’d like to buy the Varroa Easy Check system they do have some benefits.
However, you can easily test for varroa mites with a quart mason jar, flat lid, band, and some things you can find at your local farm store or grocery store.
First, you need to get ½ cup of bees. I often wondered, but they move..how on Earth do I do that?! You will want to take extra care to make sure your queen isn’t part of the bees you are trying to collect. That is the most important thing here. The next thing you’ll want to look for is a frame that is covered in bees.
Preferably bees that are actively taking care of the brood nest. As we know, varroa especially target those bees as modes of transportation. To get an accurate count of varroa mites in your hive, you are best off getting a sample from where they live. After you have double, triple and quadruple checked that the queen isn’t on your frame you can hold up your frame so it’s the long way.
Two ways to get ½ cup of bees to do a mite check:
- Have your open mason jar ready and gently push the opening of the jar against the bees and drag down. This needs to be done pretty quickly to capture a lot of bees. Repeat this until your quart jar is about half full of bees. Bees tend to fly up when disturbed, not down. If you’re doing this too slowly the bees will just fly up and away. If you’re doing it quickly enough the bees will fall right into the jar. You cannot do this from the bottom to the top, you HAVE to go from the top down. If you go from the bottom up the bees just fly off.
- You can do a quick shake of a full frame of bees into a plastic bussing tub, like this one, and use a ½ cup dry measuring cup (scoop), or your hands (I would recommend gloves for this) and put them into the jar.
Personally, I think the first way is a bit easier. It’s one less piece of equipment I need to take to the beeyard, and it’s a little easier on the bees.
How to use ether/starter fluid/alcohol wash to get a mite count
This is personally what I do to get an accurate mite count. You will one of the above methods to catch a half of a cup of bees. I used to get the recommendation to find ether to do this. However, ether isn’t readily available in the market. Therefore, I recommend using starter fluid for tractors. This comes in an aerosol can and contains 20% ether.
Then you will quickly open the jar, spray the starter fluid on the bees. The bees will die immediately, upon contact with this chemical. That is why it is sooo so soo sooo important to make sure you don’t have your queen in with the ½ cup of bees you collect to do the mite count.
You can also use 70% rubbing alcohol, or 50% isopropyl alcohol, if you cannot find starter fluid.
After you have sprayed the bees enough that they’re all dead you’ll put the lid on and shake, shake, shake the jar. You will shake the jar until you’re left with bee parts instead of whole bees. Dump it into a white plastic container so the varroa mites can be easily seen. Check in the jar to see if any varroa mites have stuck to the sides of the jar, and then count how many varroa mites you see.
How to do the powdered sugar roll to get a mite count
Some people recommend using powdered sugar to do what is called “the powdered sugar roll.” However, in my opinion, the likelihood that the varroa mites will drop off of a honey bee when they are covered in powdered sugar isn’t very likely. In all, I do not recommend this method. They may even become more stuck to the bee and not drop off at all, then you don’t get an accurate mite count. This also is not a good option if it is humid out. The varroa mites won’t detach from the bees, leaving you with an inaccurate count.
The benefit of doing the powdered sugar roll is that you are able to keep most of the bees alive. After you get ½ cup of bees into your mason jar, quickly open it and drop in 2 Tbsp powdered sugar. Vigorously shake to completely cover the bees then dump them into a white plastic container. Again, I recommend white because it will be easier to see the varroa mites on. Count how many varroa mites have dropped off, and return the bees to the hive. The other bees will work on cleaning off the powdered sugar bees, and most of them will survive.
How to understand your mite count
A mite count of less than three is GREAT! A mite count of 4-6 is alright. A mite count of above 6 means your hive is in trouble.
Regardless, you are probably going to be treating your bees with something anyway as a responsible beekeeper. This is good information to know to see how your bees are doing. You do not have to do a mite count in every hive if you don’t want to. If you do a mite count in a variety of your hives-some strong, well populated hives, some less populated hives and some that are somewhere in between there that will give you a good average as to what the mites are like in your hives.
Best time to treat beehives for varroa mites
The best time to treat beehives for varroa mites is once in the fall and once in the spring. A good time to treat in the spring is the time when you’re doing your splits. To find out more information about making splits go here. You can get pretty good coverage of your bees if you do your mite treatment in the original hive and the split. Another great time to treat is when you’re pulling supers off in the fall, put the mite treatments in. Since you have the hive open anyway and the bees are upset because you’re taking their honey, this is a perfect opportunity to put in some mite treatment too!
Best mite treatments for the fall and spring
- Apiguard – Spring
- Apivar – Fall
Some research suggests that a rotation of mite treatment may be beneficial in the treatment of mites. However, if this sort of rotation is working for your hives and keeping your mite counts low, then you might be alright to keep using this rotation.
Best varroa mite treatment for the spring
I like to use Apiguard in the spring because the bees are eager to pick up something, eat it, and feed it to the new larva. Apiguard comes in little plastic dishes that are semi-granular, almost a powder that you peel the tin foil top off and place in the hive, right on top of the top bars of the top brood box.
I also like it because I put this in at the same time I put in a pollen patty. Typically it’s still a little cold out, and I like to keep the bees wrapped up in tar paper/coroplast cover. With Apiguard for a mite treatment I don’t have to get into the bottom brood box, and it’s easy to pop the tin foil cover off and place it in the hive along with the pollen patty right on top. The bees gobble it up, and it seems to do a good job treating mites.
Best varroa mite treatment for the fall
I like to use Apivar in the fall because there are a couple of different ways to apply this treatment. I can either put two doses in at one time, or put in one dose at at time. I have to get into the hive twice, but this extends the period of time that the treatment is in the hive. There are some benefits from doing mite treatments both ways.
You may choose to do the double dose for a shorter period of time if your mite count is REALLY high. This will provide a powerful dose at once to hopefully knock out a lot of adults at one time. You may want to follow up with another mite treatment after this one depending on the temperature. If you go online each mite treatment will tell you what temperatures are needed for highs/lows. You can base your decisions on these things. Also, if you find that you just don’t have the time to go back out and do another dose, the one powerful dose might be a good option for you as well.
If you need to just keep treating varroa mites as part of your maintenance plan, doing the two doses of Apivar spread out over the multi-week time period. Please follow the directions on the packages. This may also help knock out the mites emerging in different stages, which is a helpful approach as well.
Mite treatments that just don’t work (in my opinion)
I tried a couple of different mite treatments in the past, and they just didn’t seem to be as effective or they were a pain to work with.
- Hop Guard I,II,III- comes on cardboard soaked sheets with the hop compounds. They are super sticky, cause a huge mess, and honestly I felt like I lost a lot of bees with this one because the bees stuck to it, and there was a larger area of death around these strips, not like with Apivar. You will have some death with whatever treatment you use that is a strip treatment because of placing them over the brood nest. If there was brood in there, they will die because the bees cannot get to them to feed them, and they’ll likely suffocate because of the placement.
Oxalic acid vaporizer for treatment of varroa mites
This seems like a pretty solid approach for treating varroa mites. I haven’t gotten to the point of getting the equipment to do this in my beekeeping journey so far. The treatments I had been using have been working, and haven’t felt the need to switch yet.
Oxalic acid treatments work by putting wood bleach onto a oxalic acid vaporizer plate, applying electricity, which makes the wood bleach turn to a gas. You hold this in the hive, through the hive landing board/entrance until it all burns off. I will say, if you have asthma, or other breathing issues, this may not be the best thing for you to use for a mite treatment. All mite treatments have quite the odor that burns to breathe a bit when you’re applying them to the hive. However, working quickly is super helpful. The cost of these treatments is pretty low, and it is pretty effective from the research and personal testimonies I have read.
What are your thoughts on beekeeping?
What mite treatments have you used that you particularly like and find to be effective? What things would you never try again? I would love to hear!! Please comment below!
Stay tuned in the next article about collecting honey and packaging it for sale. Everyone’s favorite part!!!!
You’ve got this. I’m cheering you on!
This is the start of something GOOD! (I can tell!)
Articles referenced in this post:
DeGrandi-Hoffman, G., Ahumada, F., Probasco, G. et al. The effects of beta acids from hops (Humulus lupulus) on mortality of Varroa destructor (Acari: Varroidae). Exp Appl Acarol 58, 407–421 (2012). https://doi.org/10.1007/s10493-012-9593-2
Ariana A, Ebadi R, Tahmasebi G. Laboratory evaluation of some plant essences to control Varroa destructor (Acari: Varroidae). Exp Appl Acarol. 2002;27(4):319-27. doi: 10.1023/a:1023342118549. PMID: 12797407.