# Online Mite Load Calculator



## Bee Arthur (Mar 21, 2015)

First of all, I know beekeepers well enough to know that *I'm about to get crucified for this*. But please bear in mind that I created this formula (and the resulting website) as a way to help people care for their bees.


https://www.mitecalculator.com/


As I say on the "Get Involved" section of the site, I'll take data from anyone willing to do the grunt work of collecting it, and use that data to continue refining the algorithm.

I hope many of you will find this as useful as I do to _help_ manage mite populations throughout the year, and communicate your experience using the calculator with me.


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## enjambres (Jun 30, 2013)

Cool idea, but why use the 24 hour drop after OAV? I find that often there is no significant drop until the period between 48-72 hours afterward, and that's when the main burst of OAV-killed mites fall. Are the bees I treat atypical in some way?

And how does that correlate to a percentage of adult infestation, which itself is not a "real number" just a stand-in that we use for making treatment decisions. When we speak of X% infestation after a sugar roll, we are talking about the percentage of the bees tested that threw off mites, not really the percentage of the total adult bees (never mind the bees in other stages of growth.)

Don't get me wrong, I _adore_ sticky boards and run one on every colony every week of the year, partly to get a mite count, but mostly because there's tons of other useful stuff to be deduced from picking through the trash. But the mites that fall to the board are not all of the mites that are dead, clumsy, old, etc., they are just a portion of the dead, clumsy or old mites in the hive that have also fallen down through the labyrinth that is a bee cluster in any known number of hours or days. There are plenty more still stuck up in the hive.

So while I count and think about the number of mites I see, I have done so much sticky boarding (once for a year I did a mite count, including counting live mites by sex and age, every day on eight hives) I recognize that whatever it is, it is not an absolute number, just a number relative to the last test(s). It's the slope of the line showing the drop numbers plotted over time which tells the tale. And there a tons and tons of variables, most of which are unknown, that control the number of hapless mites that wind up stuck in the thin layer of slightly rancid olive oil on my boards.

Just do a sugar roll every month on every hive, or a subset if you've got a lot of hives, and watch your sticky boards weekly. And you'll have all the info you need to make treatment decisions and never be caught by a sudden surge. You'll see it weeks ahead of time, which makes your treatment decisions much easier.

Sugar rolls are relatively easy on the bees if you do them right, and also done right they have the same level of accuracy as alcohol rolls for the purposes of making treatment decisions. 

If you're doing science experiments that require knowing the absolute number of bees with mites, you'll have to kill them (the bees) to do the counts. But you don't need the absolute number, outside of a lab. 

I also have some worry that treating-just-to-get-a-count is an unnecessary use that may contribute to the mites developing resistance. I'd hate for the efficacy of OA to fall off.

Nancy


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## baybee (Jan 10, 2016)

What is your definition of mite load, the one that doesn't involve the total number of bees? 

"I invite you to use the calculator below to estimate the number of mites in your colonies. Is it perfect? Maybe not, but it's proven to be pretty darn close..."

Are you just multiplying the mite count by five and calling it "mite load"?


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## Bee Arthur (Mar 21, 2015)

Thanks for the good questions. I’ll do my best to quickly address them before I start my fall honey extraction tonight . I will say that some of the questions are answered on the webpage itself.

I get a significant mite drop in the first 24 hours, with a variation that has (in my experience) correlated nicely to the pre-treatment mite load. Keeping it to 24 hours also decreases the burden on a person who’s trying to tally the number of hours since their treatment; and the point of this is to make it easier to test for mites so people actually do it.

The mite load is calculated in both phoretic and true percentage. The phoretic is what you’d get from a sugar roll or alcohol wash, and represents the percentage of “free ranging” mites in the hive to the number of bees in the hive. The true percentage attempts to give estimates on the actual total number of mites in the hive, including those under the capped cells. As I say on the website, this true percentage should really be taken with a grain of salt because I couldn’t find much supporting information about how the mite load increased with each frame of brood. (I did find some info, but not much.)

I understand that the mites that fall to the board don’t represent all the mites killed during a treatment. The nice thing about the formula is that it doesn’t rely on the actual number of mites killed during a treatment. Instead it relies the number of mites that fall in a given time, in proportion colony size.

There are a lot of variables, no doubt. But a quick hit from OAV, I have found, tends to produce a fairly reliable predictor of the mite levels that were in the hive prior to the treatment. The hard part is collecting the data, correcting it for some of the most obvious variables, and then monitoring for a correlation. I’ve done hundreds of samples (sugar rolls and sticky board counts) before and after treatments, with very few of those (<5%) being thrown out as outliers. By the way, do you know how hard it is to get motivated to do sugar rolls on the same hives for two consecutive days? It’s not easy, LOL. 

I’d also like to see more beekeepers doing more regular sugar roll tests, Nancy. But for the reasons I state on the website, it just doesn’t seem to happen. Also, during the process of collecting data I’ve found that it’s not always reliable to use a small sample of your hives to make treatment decisions for your entire bee yard. Some hives get into big trouble with spikes in their mite loads, even with the rest of the colonies sitting at comfortable mite levels. I assume this is due to mite bombs that resulted from one of my colonies robbing out a neighbor’s hive that died due to heavy varroa infestation.

I wouldn’t generally treat just to get a mite count. There are a couple times of the year that I know I’ll be treating regardless. As far as over-treating leading to OA resistance, I’d argue that this leads to _less_ treatments because it’s helping the beekeeper make informed decisions, and should lead to a net decrease in treatments; especially considering the possibility that more effective treatment decisions will lead to fewer mite bombs.

One big unknown for me is whether the samples from my hives will be significantly different from other people’s hives. That’s a possibility, and it’s why I’ve got the option on the website to submit your own data. I’d love to use samples from beekeepers all over the world to create a second calculator. I wouldn’t abandon my own data because I have the most control of its quality. But I would like to have a “community calculator” to see if there’s a big difference in outcomes.


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## Bee Arthur (Mar 21, 2015)

Today was a good example of how this calculator comes in handy for me. A few days ago I sugar rolled and had some surprisingly high mite counts, as tends to happen in early October. So I set out to treat each of my hives today, but it's going to be too cold for the next few days to comfortably open the brood chambers to collect bee samples. No worries though, because tomorrow I'll just count the mites on the sticky boards, and then make my follow-up treatment decisions based on mite loads I get from the mite calculator.


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## Bee Arthur (Mar 21, 2015)

Here's a short video explaining how to use the mite calculator. https://youtu.be/dr7wgfa9rWE


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## Kcnc1 (Mar 31, 2017)

Hey Maude, 

I like your idea and appreciate that you are asking for input to refine it. Data collection is good if it can be then focused to action. I’ll review, play with it and see where this takes us. Great job initiating this n


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## Bee Arthur (Mar 21, 2015)

Kcnc1 said:


> Hey Maude,


LOL...Maude...that's great.

Thanks. I knew it wouldn't be very well-received for a number of reasons. But in the end, I'm just trying to create a way of monitoring mites that could encourage more beekeepers to actually monitor their mites.


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