Monday, February 25, 2008

Lesson 28: Varroa Mites ( 217-427-2678

sherichristian When you call us here at Long Lane Honey Bee Farms, there are two people who will probably be answering the phone. My wife, Sheri and our youngest son Christian. Christian likes to get his two cents in on the phone conversations too, so you might hear him in the background. I hope little Christian, who is now 5 months old, will one day become a beekeeper. If he does, I'll have to teach him how to keep bees from being destroyed by varroa mites. But, while we wait for him to grow up, how 'bout I teach you...
A bear devouring a hive is an attention getter! A flood or hurricane washing hundreds of hives down stream is terrifying. These are huge calamities which beekeepers go to great lengths to prevent. We'll put up electric fences or put our hives on poles to protect them from bears. We'll elevate our hives to tower above flood plains. However, many beekeepers do very little to protect their hives from what might be their biggest threat. We seem not to take small things very seriously...small things like the tiny Varroa mite. The Bible says it is the little foxes that ruin the vineyard (Song of Solomon 2:15).
Mites are visible with the naked eye, but they are small. I wanted to put a picture of a mite on a bee in here, but fortunately for me, I didn't see any mites on the bees I tried to examine. But if you google "varrora mites" you'll see plenty of pictures. Older mites become dark and are easier to see than young mites which are almost clear at first.
In 1987 mites were introduced into the US probably as the result of imported bees. Within the next few years mites nearly destroyed all feral hives. A feral hive is a natural hive not kept by a beekeeper, like a wild hive in a tree. But the mites did not stop at feral hives but reached deep within the bee yards of all beekeepers, driving many commercial beekeepers out of business, and hobbyist out of a hobby.
I remember in the early 90s a friend of mine said he was done keeping bees because it was cheaper to buy honey than produce it. Mites drove him out of the hobby. They shouldn't have!
All hives will have some mites. Mites are found in a bee hive feeding on pupae and on adult bees. It is important for the beekeeper to understand the basic reproduction cycle of the varroa mite which takes place within the honey bee capped brood cell. An adult mated female mite is called a foundress. The female mite enters the brood cell just before it is capped. She then lays her eggs in the cell while munching on the pupae. First she lays an unfertilized egg and it develops into a male mite. Then her other eggs are fertilized and develop into females. Mites mate with siblings. After the bee emerges from the cell, so do the adult female mites, looking for a new cell. Mites are carried from one hive to another by hitching a ride on the bees.
Good news: We can successfully keep bees even though we have mites!
Okay, to be fair, I must tell you what you will be told by most entomologist and bee inspectors and what you'll read in most beekeeping books and magazines. They give you a standard approach for dealing with mites. So, I'll give you what they say, then, I'll give you my thoughts on the subject. For the record, their way is not bad, wrong or unwise. It is sound advice. And keep in mind that I am not a scientist nor an entomologist anyway, right? I just don't like to use chemicals in my hive. That's where we differ.
Most will tell you to do a mite count to determine if you are over the "economic threshold". This is a fancy way of saying there comes a point where too many mites can be bad for your hive. However, that's like someone telling us there is an economic threshold for rattle snakes in your house. One is too many right? So it is with mites. They can carry viruses and when they bite our bees, viruses are spread. So one is too many, but it is practically impossible not to have some mites.
This economic threshold is determined by placing a sticky board under your screen bottom board for 24 hours and then counting the mites that are stuck to the board. Don't buy those expensive sticky bottom board. Make your own. I'll write a future lesson on how to make a lot of these cool things. Based on your number, you determine whether you are over or under the economic threshold which basically means either you treat with chemicals or you don't. At least this is what is commonly suggested. If you have more than 50 mites within a 24 hour drop period, then it is recommend that you treat your bees for mites.
Of course, I have my opinion right? First, the sticky board count method concerns me. Here's why. If I have a very hygienic hive, they may be cleaning out the mites and the mites might naturally fall onto my sticky board. So, I might see a count of 50 mites, but it may not mean I have a problem, but just the opposite. On the other hand, if I only have 5 mites on my sticky board it may cause me to think I do not have a problem, but in reality, my brood cells could be full of mites and mites might be all over my bees and just hanging on exceptionally well.

So I do not trust the sticky board drop test. Let me tell you how I determine my mite levels and then what I do with that information.

1) Digital photography. I photograph several frames, take the photo back to my pc, and zoom in on my drones and worker bees and look for mites.
2) Open drone brood cells and some worker cells. I actually will pull out purple eye pupae and examine the number of mites on the pupae. Mites love drones because queens emerge from their cells in 16 days, workers in 21 days but drones not until day 24, giving the foundress more time to reproduce before the drone merges.
These two methods give me a much better read on my mite levels.
Mites will be in your hives. They are impossible to avoid entirely, but they can be kept to a level that will not disrupt the hive as much.
While it is true that for many years the answer was to treat with chemicals, this is not a good management practice in my opinion. With all our chemicals we seemed to have developed a super mite that is now resistant to our chemicals while at the same time, some of these chemicals have made our queens and drones weaker. Some of the approved chemicals can be absorbed in the comb for 5 years or longer.
Within agriculture, there has long been an approach called IPM for Integrated Pest Management. IPM is an integration of several approaches to keep mites below the economic threshold. While treating with chemicals is part of IPM, that is a step we try to leave out.


WHEN HONEY SUPERS ARE ON: Screen bottom board, small cell foundation, drone brood foundation freezing, hygienic queens and strong colonies.

First, if you are just starting out with a new package this year, it will be vary rare to have a mite problem within your package of bees. It is possible, but I typically never see mites that much in the spring or early summer. I just don't care about mites until July and August. Mites become more aggressive and spread more rapidly in late summer around August.
You see, I want my bees to produce honey from April through the second week of August. And they do. I try to stay out of my hives as much as possible during heavy nectar flows so as not to disrupt their bringing in all that honey that my customers are lined up in my driveway waiting on! And, you can't use chemicals any way when you have honey supers on the hive. If you do, your customer's honey will be contaminated with chemicals that can harm humans. You DON'T WANT THAT!!
But, there are some things I can do when my honey supers are on to cut down on mites. First, I use screen bottom boards. I used to be a staunch solid bottom board fan until I experimented with a screen bottom board. Wow! I immediately converted all of my solid bottom boards over to screen bottom boards. When mites fall to the bottom of a hive with a screen bottom board, they are gone, and cannot make it back in. On a solid bottom board, they simply wait for the next passing bee to get on and ride back up to infest the hive.
A screen bottom board also provides ventilation and a cleaner hive allowing colony debris to fall on through. Here in Central Illinois winters are harsh, sometimes getting well below 0 and windy. I do not cover my screen bottom boards. I leave them open all winter to allow ventilation to evaporate the moisture out of my hives. It is not the cold that kills bees, but being cold and wet from their own condensation within the hive from poor ventilation. Screen bottom boards will not get rid of all the mites, but it is one of several approaches that contributes toward keeping mites below the economic threshold.
drone foundation Secondly, I use drone foundation to lure the mites. You see, as I said earlier, mites like drone cells because the foundress mites have a full 24 days to develop their prodigy since the drone is the longest in the cell. So, you can lure the mites off of your worker cells by placing drone foundation on the outside edges of your brood hive bodies. We sell a one piece drone foundation plastic frame. The cell size is for drone cells so the queen knows to lay only unfertilized eggs producing drones. Then, your mites run to these cells and after they are capped, you pull the frames out, put them in a plastic trash bag, freeze them overnight and your mites are dead. Scratch open the cells and place it back in hive for the bees to clean out, and they will! They get rid of all the mites and dead drones. These frames are a bright lime green so you can easily identify your drone frames. We sell these frames for $4.99 each, much cheaper than chemicals. These can be purchased from our website at: under frames and foundation. By scratching the cells open after freezing, it allows you to keep the drawn comb intact, but encourages the bees to clean out the dead mites and drones from the cells. If you scrap the wax completely off, then it just takes more time for the bees to draw it out again.
Thirdly, small cell foundation. I'll skip small cell foundation, because it is not a for sure thing and it should be tried only by very experienced beekeepers. It has to do with bee regression and let's just say that's a whole different lesson. But many claim that by using 4.9 mm cell size foundation, the cells are capped a day sooner, throwing off the mite's cycle and not allowing them to get in on time. Some studies have shown this not to be effective, while other studies show it helps control mites.
Fourthly, work is underway to produce a queen that is so hygienic that her daughters might have the characteristic of detecting a foundress mite, opening the cell and dragging the pupae and mites out before they reproduce. I have attended a conference where this was discussed and the results were shared. It is promising! We may not have to wait, as some suggest that bees are now becoming more aware of mites and are actually taking them out of the hive.
Again, if you find you have a queen and her daughters are keeping mites out of the hive, then that is good queen stock to breed from!
Finally, the answer to all colony problems in my opinion is to keep strong colonies. A strong colony avoids most diseases and pests.
When your supers are off of your hive, powdered sugar dropped in the deep hive bodies can be very effective at controlling mites. For a complete lesson on how to apply the powdered sugar drop, check out our lesson at the link below:
When using powdered sugar, the bees actually clean each other off, and mites go too. And mites get the sugar in their suction cups and can't hang on any more and fall out too! It is impressive.
There you have it! Some natural ways and IPM ways to manage your hives and keep mites from destroying your hive.
I've been working on several more lessons at the same time I've written this one. The next one will be on record keeping. A failure to keep beekeeping logs can result in the failure of your hives.
Remember, call in your hive orders as soon as possible so you can get your equipment on hand soon. So call us for your hive order or bee order. Call us between 9am - 5pm Central Time. We'll be happy to help you get what you need to start keeping bees.

We have lots of hives listed at our main website at: We'd love to earn your business.

Remember... BEE-HAVE Yourself!!

David & Sheri Burns

Long Lane Honey Bee Farms