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Oxalic Acid Calculator

On my previous post “Nuc Calendar Generator”, I wrote about a spreadsheet program that I created in order to help us quickly generate a calendar with all of the necessary information that we need to aid us in making our nucs. At the end of that post I mentioned that I would be writing a follow up post to tell the story behind the “Oxalic Calculator” tab. So without further ado, here is story:

Soon after I had finished my Nuc Calendar Generator program, I was invited by a friend to attend a social gathering. During this gathering, I ran into a gentleman that mentioned that he was making mead (honey wine) for his brother’s wedding. Being a mead maker myself, we struck up a great conversation. The conversation soon transitioned to beekeeping after he mentioned that he would like to keep his own bees to make mead using his own honey. He had already done a lot of research on bees, so he was full of questions. Of course, being a “treatment free” beekeeper, I had to give him my thoughts on treatment free beekeeping and why its the best approach for a hobbyist (in my humble opinion). During that entire conversation, I noticed an elderly gentleman (that neither of us knew) that was “hanging around” listening to our conversation, so we asked him to come join us. It turns out that the elderly gentleman was a retired beekeeper (that still kept several hives “just to stay busy”). He immediately corrected me on why it was so foolish to be treatment free. After all, he had ran a business for years keeping happy bees with the good old (over) treatment method. I respectfully disagreed, but we did have a good conversation about the advantages and disadvantages of treating bees, specifically for varroa. It turns out that this gentleman had used a varroa treatment for his bees (and still treats his current ones) using a chemical smuggled in from Mexico, as it is illegal to use and purchase in the US. He didn’t give me the name of it, because he couldn’t remember, or at least that’s what he said.

I have much respect for old-timer beekeepers and when I am fortunate enough to speak to one, I always try to learn from them. This particular beekeeper left me thinking about something. He said that when you have lots of beehives in one location, sooner or later you’ll have a varroa outbreak that will take out most of your bee yard. After all, having such a high concentration of hives in one area is not natural. He mentioned that not having a backup treatment plan is just plain foolish. On that point we could both agree. In past years, before we were in the almond pollination business, we weren’t afraid to lose bees to varroa. It’s how we ended up where we are today with very good survivor bees. However, we are now in a position where we must deliver a specified number of hives to our almond grower. This year, it means that we can only afford to lose about 8% of our bees and still meet our target. As a smart business decision, we should have a backup plan.

I personally don’t like to take medicine, although I’m not opposed to it either, and I will certainly take any medicine in a life and death situation. I think that I feel the same way about bees now. We need to have a backup treatment plan in case we ever experience a severe varroa outbreak that represents a life and death situation for our business.  I’ve thought about this before and I’ve even done some research on the best “organic” treatment methods but haven’t really taken any actions. I’ve decided in the past that if I had to treat with something during an emergency, it would be Oxalic acid. It’s not as effective as the hard chemicals because of the small residual time and the fact that it won’t kill mites present inside the capped brood. However, it can be pretty effective especially if you treat during broodless periods, and the best part is that it is an organic acid (like citric acid).

Well, since I had just finished making a Nuc calendar generator, I figured why not make an Oxalic calculator as well? If you are going to treat by using vaporized Oxalic acid then you don’t really need a calculator. I suppose that vaporizing Oxalic acid is a good way to go if you only have a few hives, but it can be slow and time consuming and the vapor is hazardous if you inhale it. For these reasons, I would use the liquid sugar/Oxalic dribble method instead. With this method you can make a big batch and treat as many hives as you need to fairly quickly and the solution is safe to handle. If you want to read more on the Oxalic acid treatment methods, I recommend reading the articles on the subject written by Randy Oliver on his website.

If you are going to use the liquid sugar/Oxalic mixture, you will need to follow a specific recipe. How strong you want the mixture will determine what recipe you follow. Also, the recipe changes if you are using wood bleach (diluted Oxalic acid used for commercial applications) or pure laboratory grade Oxalic acid crystals. Lastly, when following the recipe, you will need to make sure that your measurement units are correct (as everything needs to be weighed). There is a specific range of treatment where Oxalic acid is effective. Too little and it won’t kill mites and too much and it will kill your bees, so you need to be careful to get the mixture right. I’m the “measure twice cut once” kind of guy, except in this case its “get the calculations right once and use them forever”.  With this in mind, I created the “Oxalic Acid Calculator” and included that into the Nuc Calendar spreadsheet. This way if we ever need to treat, I can pull up the calculator and quickly generate a recipe without having to do lots of research.

Like I mentioned, treating with Oxalic acid is most effective if done during a broodless period when all of the mites will be exposed to the treatment. When you create nucs, you are making a broodless period between the time that the last eggs from the old queen hatch and the new queen’s larvae are capped. If you wanted a “clean” start to the nuc colony, it’s a very good time to treat them. For this reason, the Nuc Calendar Generator also provides the best dates to treat the nuc, reference Figure 1 below:

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Figure 1: Treatment window shown in the Nuc calendar

 

To end this post, I will describe how the calculator works:

You go to the “Oxalic Calculator” tab. Then you go to the “Input Parameters” section (at the very top) and select your four input parameters. Your options for mixture strength are Strong, Medium, and Weak. The options for Oxalic type are Pure and Wood Bleach. The number of colonies is simply how many colonies you wish to treat (at a dose of 50 ml per colony). The last input parameter is to select large units or small units. Large units are Kilograms (kg), Pounds (lbs), Liters (l) , and Gallons (gal). Small units are grams (g), Ounces (oz), milliliters (ml), and quarts (qt). I included this feature because if you are making a small batch, you likely don’t want to see 0.062 pounds. You are going to be measuring in ounces. The inverse of the same concept applies to large batches. I find the metric system to be much easier, so I use metric personally, but I included the US standard units for those who like harder math conversions. Reference Figure 2 below:

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Figure 2: Input parameter of the Oxalic acid calculator

Once you’ve entered the inputs into the calculator, you can find the recipes in both metric and US standard units, reference figure 3 below:

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Figure 3: Oxalic recipes in metric and US standard units

The page can easily be printed for your records. It might look something like what is shown in figure 4 below:

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Figure 4: a printed Oxalic calculator form with notes.

 

I’ve already tested the calculator by creating a batch of medium strength Oxalic solution and treating 10 hives. The results were inconclusive as I didn’t have any baseline varroa counts prior to treating. However, after 48 hours, I inspected the hives and found a few dead varroa mites on the bottom boards. The most that I counted was around 10, but I suppose that the bees could have removed some as I wasn’t using sticky boards (I have never actually used a sticky board). At the very minimum the solution killed mites and didn’t kill bees, which is a good sign. I used the treatment tables provided by Randy Oliver (very knowledgeable in Oxalic acid) to calibrate my formulas, so I am confident that the calculator will work as intended.

Well, it took an unexpected run-in with a retired beekeeper to finally  motivate me to get in motion with a backup treatment plan for varroa. Our long term strategy will never change as we firmly believe that the best plan to fight varroa is breeding bees that fight varroa (I’ve documented this in previous posts). But in a pinch, we now have a viable backup plan.

 

Nuc Calendar Generator

Anyone that manages a lot of beehives and multiple bee yards will tell you that record keeping gets harder and harder the bigger you get (especially if you’re a part time beekeeper). Up until this year, my brother and I had relied on text messages, a white board, and good old calendars to keep track of what beehives/beeyards needed what. This year we had a bit of a “misunderstanding” in one of our beeyards with regards to making up mating nucs. I setup the cell builder colony (and did the grafting) and my brother was supposed to make up the mating nucs. Well, let’s just say that the nuc’s never got made…

This little mishap got me thinking. Wouldn’t it be nice to have a “program” where you enter the date that you are making nucs and it will generate a calendar with all of the pertinent information? Useful information such as when queen cells are capped, when to make mating nucs, when to insert queen cells, when the cells hatch, when to expect new eggs, etc.  Then I realized that I make “calculators” for things all the time due to my day job and I thought, why not make one? In my opinion, the easiest platform for such a program (to generate a calendar) is MS Excel, as it has  many built-in predefined date and arithmetic functions. So I sat down and created what I lovingly call: Estrada Farms nuc Calendar Generator. It’s not the best program out there I’m sure, but it gets the job done and will make generating such calendars much less time consuming.

It was only until AFTER I created my calendar generator that I decided to check the internet to see if anyone else had come up with such a generator already. A quick google search turned up a website that gives you a list of dates, but doesn’t generate an actual calendar view. I find the calendar view to be much more helpful than just a list of dates because you can see the days of the week (and you get a sense of when to do the task relative to your “today”). Writing such a program in HTML (or any web language) would be much harder, which is probably why it doesn’t exist and its the reason why I ruled out that option as well.

After I created the nuc calendar generator a friend (and hobbyist beekeeper) asked if it would work for walk-away splits as well. I thought about it and realized that all dates would be shifted by a day. I didn’t want to rework my formulas so I took the easy way out and just added instructions for splits in parenthesis next to the instructions for nucs.

I intend to share this spreadsheet program with a few people so the remainder of this write-up will be somewhat of a “how to” use the program.

The first step after you open the file, is to go to the right month tab and click the “Enter Date” button on top. See figure 1 below:

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Figure 1: Step one in calendar generation process

After you click the “Enter Date” button you will get a popup window. The popup window will have a nuc option on the left side and a split option on the right side. In this example we will select the nuc option. click the drop-down arrow on the date picker as shown in figure 2 below:

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Figure 2: Step two in calendar generation process

After you click the drop-down arrow on the date picker you will get a small calendar to help you select the date. The date you will pick is the date that you will be removing the queen from the cell builder colony. Reference figure 3 below:

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Figure 3: Step 3 in calendar generation process

If you prefer to use a different date as a baseline (such as when you graft) then you can “play” with the dates as necessary to get your desired results. When planning mating nucs, I prefer to use the date that the queen is removed as my baseline date.

After you select the right date, click the OK button and you will see the calendar generated. Make sure that you are in the correct month (based on the date you chose). reference figure 4 below:

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Figure 4: Step 4 in calendar generation process

If you start mid-month, the program will generate the right activities in the right months. For example, if I had chosen a date of April 15th, half of my activities would have been put on the May calendar. I used a date of April 1st in the example to try to capture as much as possible in one month.

Please be aware that I used “optimal” dates for all activities.  Some dates may change due to your specific conditions. A good example of this is the date that your queen will start laying new eggs. We all know that weather is a big factor in when queens mate and begin laying. So you will have to monitor your specific situation and make sure to account for the differences.

I hope to start using this calendar generator next year (2018). It is very likely that after I use it in real time that I’ll come up with other ideas and enhancements to incorporate into the program (it always happens that way). For now I’m pretty excited to start using the program and to hopefully have fewer “mishaps” due to lack of organization.

P.S. for those of you who are pretty observant: You may have noticed the “Oxalic Calculator” tab or the “Oxalic Treatment Window (if necessary)” task on the calendar. There is a story behind that and it will likely be the subject of my next post.

Toxic Plants

Plants that are toxic to bees are not a big issue for most beekeepers. It is safe to assume that most locations have enough diversity of forage that any toxic pollen or nectar would be diluted enough to not be deadly to your bees. However, any given year you may experience some hive “issues” that could be attributed to toxic pollen or nectar. The issues could range from mild (bees are affected but will survive) to severe (it kills the hive).

I am fortunate enough to live in the Tehachapi mountains of California that provide a great spring nectar flow that consists mostly of wildflowers and a solid fall flow that consists mostly of buckwheat. And then there’s the highly toxic California Buckeye tree that blooms from mid/late May to late June. The California Buckeye is found throughout all of the California Sierra Nevada mountain range at an elevation of around 3000 to 5000 feet.

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I don’t know if anyone knows whether it’s the Buckeye pollen or nectar (or both) that is toxic to bees, but it sure is toxic (the worst part is that the bees seem to love it.) Buckeye poisoning is easy to spot because it is toxic only to the larvae. If you inspect a hive during and after the buckeye bloom, you’ll see a lot of young larvae but no capped brood. In other words, the larvae die before they are capped. The inability to raise new bees eventually leads to hive collapse. So your hives won’t really “die” until four to eight weeks after the buckeye bloom.

In the past, especially during our historic California drought, we’ve had pretty good success in getting hives to survive through the buckeye bloom, but this year was different. We finally snapped out of the drought and had a very wet winter and spring, which contributed to a massive buckeye bloom. Before we could react to it, some of our hives had already gotten a big dose of it. But as always, for the sake of knowledge, we turned a bad situation into an experiment (might as well right?). We moved out a third of our hives about 2 weeks into the buckeye bloom. We moved out another third of our hives about 3 weeks into the bloom and left the remaining third to tough it out through the bloom. We can only move one truckload of bees (about 18 hives) per weekend, so that’s the way it had to work out.

The bees that we moved out first did show a “dip” but recovered well (when inspected a few weeks later). I suspect that the buckeye only affected about one brood cycle before they used up all of the toxic stuff. The small interruption in brood production should have helped with any varroa mite issues (although I don’t have concrete measurements). The bees that we moved out in the second wave had about a 40% survival rate. The bees that stayed at my house had a 10% survival rate. Oddly enough, the two hives that survived at my house were both very weak splits that we had made for swarm prevention purposes (by removing the queen and a few bees from the strong hives that we didn’t want to swarm). My assumption is that the small splits survived because they didn’t have the foraging capacity to bring in enough of the Buckeye pollen/nectar. But it’s safe to say that any strong hive at my house would have died this year (0% survival rate).

This is why it is important to know if you have any toxic plants in your area. Perhaps you notice hive “issues” at a particular time of the year every year and you haven’t been able to figure out what is causing them. It could very well be that they are foraging on toxic plants. But knowing what it is and when it blooms is the first step to figuring out a plan to overcome it. It may be prudent to move your hives out of the area, or perhaps you can get away with using pollen traps to limit the incoming pollen (or removing all pollen frames) or making splits or a combination of all of the above.

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California Buckeye blooms are beautiful, but deadly.

If you live in (or close to) the California Sierra Nevada mountain range or keep your bees there, make sure that you check the area around your apiary to see how many Buckeye trees are present. As long as there are plenty of other flowers for your bees to forage on, they can likely buffer a few trees. But if you live in an area where entire mountainsides turn white from buckeye blooms (like I do), then you really should consider moving your hives out of the area during the bloom. Even if you don’t have any issues with toxic plants, it’s never a bad idea to familiarize yourself with the toxic plants that may exist in your immediate area and your local region. You never know when this information may come in handy.

Bees forage for wax?

If you ask any beekeeper what bees forage for, you’ll get this answer 99% of time: Nectar, Pollen, and “stuff” to make propolis. This is a perfectly satisfactory answer, especially from a practical standpoint. However, it is important to note that bees can and do forage for anything that they need. Today, we’ll talk about foraging for wax.

Have you ever had a colony die out and purposely left the honey frames exposed for other bees to clean up? At first, you notice how bees flock to the frames and eat out all of the honey. If you leave the frames there long enough, you may also see that the frames of new white wax still have some bees crawling around on them. If you inspect those bees even closer, you may see them ripping pieces of wax off of the frame with their mandibles and sticking it to their hind legs, much like they do with pollen. The result will be (could be) a frame with jagged edges around the cell, but it takes very close inspection to notice. As far as I can tell, they only go after the new wax, probably because it is more pliable and they can put it into production right away as if it was newly secreted wax.

We’re big on having our bees pull their own wax every year. However, if we expect them to pull wax in the fall, we usually provide wax foundation to speed up the process. Last weekend, while building some frames with wax foundation, I noticed a bee actively “foraging” for wax on the sheets of wax foundation that I was using. So I took the opportunity to document the behavior.

 

 

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If you pay close attention to the video below, you’ll see the bee ripping off pieces of wax and using her middle legs to stick the wax to her pollen baskets in her hind legs. You can also clearly see the lumps of wax on her hind legs.

 

Is there a practical application for this behavior? Not for most people. But I would say that if you use foundationless frames (or a top bar hive) and expect your bees to build new wax every year, you may want to consider leaving some wax around for the bees to reuse as needed. Most foundationless beekeepers crush and strain their honey and are left with new wax (from the current year) as a byproduct of the honey extraction process. The wax is left with a honey residue and most people let their bees clean it up anyway, so why not leave it there a little longer in case the bees want to reuse it?  I caution to only do this with new white wax (which is what most foundationless beekeepers have every year) as they don’t seem interested in the old combs. Also, be careful that you don’t leave any frames with honey/pollen unattended as that will encourage wax moths and other pests to move in.

As I mentioned, most beekeepers will have no practical application for this behavior. But if you hadn’t noticed it before, next time somebody asks you what bees forage for, you can add wax to the list.

The Fresno Experiment – Exponential hive increase

Although I live in the Tehachapi Mountains of Kern County, I have to travel to Fresno California a few days a week due to my “real” job (engineer). Coincidentally, for my “side” job (beekeeper), our Almond pollination contract is also in Fresno California. After the 2017 almond pollination season was over, Steve, my co-worker from Fresno asked if he could buy a beehive for his dad who wanted to have bees around to pollinate his fruit trees. We kicked around the idea for a while and finally decided to take two hives to Steve’s house in Fresno after we pulled the hives from the almond orchard (Steve decided that he wanted a beehive as well). The plan was to split those two hives so Steve and his dad could each keep a split. However, when we inspected the hives a few weeks later, we found that the queen in one hive had died and the hive had a laying worker(s). So to start out with, we really only had one good (queen-right) hive as the one with the drone layer(s) was very likely going to fail.

Out of curiosity I suppose, Steve asked how often you can split a beehive in one year. In other words, if you start with one beehive, what is the maximum amount of queen-right beehives that you can have by the end of the year? I answered that I didn’t know, as I’ve never tried it before and there are so many variables to consider. But it did leave me wondering how many hives a person could make if their only goal was to make more beehives (not honey production), and so the Fresno Experiment was born.

The premise of the experiment was to find out how many hives we could make that would be able to overwinter on their own stores of honey (or very limited feeding).

The experiment started in mid-March and the good beehive consisted of 8 frames of bees and the bad hive had about 10 frames of bees (and a lot of drone brood). The first two moves we made were:

  • Put a frame of eggs and young larvae from our good hive into our failing hive to see if they would raise a queen (Although it was unlikely to work). In exchange the good hive received a frame of pollen/honey from the bad hive.
  • Split the good hive by removing the queen and two frames of bees and one frame of honey/pollen into a nuc box. The remaining bees (5 frames) in the original good hive went to work raising a new queen.

In mid-April we checked all three hives again. The original hive with 5 frames of bees had raised a new queen that was already laying eggs in a very good solid pattern. The nuc box with the original queen was also doing great raising bees and collecting resources. The failing hive failed to raise a good queen, so we combined it with the original queen, which we moved from the nuc box to the single 10 frame box.

In mid-May we checked the two hives and they were doing great. They were growing very fast so we decided to put a deep super on each hive.

In mid-June we checked the two hives and they had filled most of the second super with honey, pollen, and some brood. At this point, we picked the strongest one (the new queen from March) and moved her to a new hive with 2 frames of bees and left the remaining bees to raise new queens.

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Figure 1: The bees were very crowded so they started building comb around the queen cells.

We made a frame to hold queen cell cups and grafted 14 queen cells, using the eggs from the original queen. All 14 queen cells were accepted and the hive went to work raising 14 new queens. Crowded bees make good queen cells, but if you leave too much room they will build wax around the queen cells as shown in figure 1.

Ten days later we made up 12 nuc colonies and inserted a ripe queen cell into each nuc. We only did 12 colonies because we were only able to pull enough resources from both hives to make 12 – 3 frame nucs. The goal was to get at least two frames of bees and one frame of resources for each nuc.

Three weeks later in early July, we inspected the nuc’s and found 10 laying queens. However, since the nuc’s were in the same yard as the original colonies, we experienced some drift back issues where some bees migrated back to their original hive location (we left a nuc in the original location of the source hives to catch the drifters). The drift left  some nuc’s seriously debilitated, so we decided to combine the weak nucs and keep the best queens. After combining, we had eight new queens in new colonies. One brood cycle later, we moved all of the nuc colonies into 10 frame boxes.

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Figure 2:  Steve holding a frame of new wax and capped brood.  Picture taken in July.

In early September we checked the hives again and all but two of them were overflowing with bees. We also noticed that most of them had 2-3 frames of honey. The strong hives got an additional deep super. Due to the location of Steve’s house in a residential area with plenty of mature trees and shrubs, we expect to get a solid fall flow. This should allow most of the hives to fill the top super with honey by mid-November. If they don’t, then we may have to feed them some syrup so they have enough to last them through our coldest months (Mid-November to Mid-February), but this should be minimal.

Although the colonies still have to overwinter, I think it’s safe to say that we got the answer we were after. In Fresno California, if you start with one good beehive, you can end up with ten good hives by the end of the year (1 original queen + 1 March queen + 8 July queens). Also, if we had moved our July nucs to a different location to eliminate drift back to the original hives, we would have been able to keep 2 additional colonies (although they would all be a bit weaker). The biggest key to success in this type of experiment (exponential increase) is to have a location with decent year round forage (especially pollen).

Overall, Steve and I had fun conducting this experiment (and he even got a beekeeping 101 class in the process). I have to admit that I was impressed by our results. You sure can reproduce bees quickly if you get a few fundamentals right. I warn anyone that tries to reproduce these experiment results that buying all that new bee equipment can get time consuming and expensive. But if you sacrifice 1 years’ worth of honey from one hive, you can get 10 times the amount the following year!

Late Summer checkup and thoughts on Varroa resistance

Here in California we had a very hot summer. For most of June, July, and August we’ve had temperatures over one hundred degrees. Most gardens with full sun exposure did not do very well and neither did bees. We were really able to see the difference between hives that were shaded (or had some shade throughout the day) and those in an open field fully exposed to the sun. On average the shaded beehives fared much better, with the exception being that they attract more hive beetles. As a matter of fact, we barely ever see any hive beetles on the hives that are fully exposed to the sun; But we are spoiled here in California and hive beetles aren’t a big issue at all (at least not for us).

It was the last weekend of August and we hadn’t really done any hive inspections all summer, so it was about time to get out there (in the sweltering heat) and check some hives, especially our spring splits and new queens. About three quarters of the hives we checked were doing very well and had plenty of honey/pollen stores and the rest will need feeding in late winter (to some extent). Unfortunately the hives were too busy carrying water all summer and not foraging. But oh well, at least we get mild winters…

Today, I want to concentrate on some thoughts about breeding for Varroa resistance that were inspired by our recent hive inspections. Specifically, I want to expound on the concept of the constant and ongoing process of breeding for varroa resistance and how (in the near future) we can’t expect our apiary to reach “varroa resistance” to the point that we quit breeding for it.

In our personal experiences, we have found that we can take the most hygienic queen and create a batch of queens from her, yet the degree of varroa resistance (using the term “varroa resistance” very loosely)  in the daughters will vary quite a bit. For example, in a yard of 18 hives, we found one that let varroa get out of control, yet the hive next to it was showing great signs of hygienic behavior. We cannot guarantee it, but it’s very probable that these two hives have queens that are sisters (share the same queen mother). We can guarantee that the grafted queen cells that were put into these hives were sisters, but I suppose that there always exists the chance that one of the queens was superseded (as we only got around to marking the queens during this same inspection).

First, let’s take a look at the hive that was doing poorly. By doing poorly, we mean that it had too many varroa mites, other than that it was full of bees and had plenty of resources (all of the hives at this site are on double and triple deep supers). I have a pretty good eye for varroa and while looking through the brood chamber for the queen, I managed to spot a total of two bees with a varroa mite attached to them. We might let one slide, but not two. As a general rule, if you can see multiple varroa mites, there are many more lurking around, probably in your drone brood.  So we pulled a frame of honey that also had plenty of capped drone brood and sent it to our laboratory for analysis. By laboratory, I mean that I had my two nieces and my daughter pull out larva (drone and worker) and count how many cells were infested (so I can calculate an infestation ratio).  Here are some pictures:

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Based on a sample of 140 drone cells, 76 of them were infested with varroa (that works out to 54.3% infestation). On a sample of 111 worker cells (from the same frame), 5 of them were infested (4.5% infestation). That told us two things: First off, that this queen needs to go. I personally killed her on the spot and we will introduce a frame of eggs from a different hive in a few days (note for beginners: all queen cells need to be destroyed first) for the hive to raise a new queen. Here in California, we still have plenty of drones in September to mate the new queen, so the hive has a good chance of making it.  The second thing that this experiment told us is that indeed varroa mites prefer to infest drone cells whenever possible, but of course, this was no surprise.

A side thought: If a person wanted to treat this hive, they would simply wait about two to three weeks (depending on when you start counting) until all of the old queens’ larva hatched out and treat the hive. Since there is no brood present, all of the varroa mites will be exposed to the treatment and you would get maximum efficiency. If you’re like us and don’t treat your hives, then you just sent the colony into a “broodless” period  and many mites will die of old age without being able to infest the new batch of larvae from the new queen. The broodless method works well for us, but if the hive doesn’t make it, then oh well, we tried.

Now on to the good hive. Ironically, the hive right next to the infested one was doing great and showing very good signs of hygienic behavior. The hygienic bees remove worker pupa that are infested with varroa mites. The pupa that are removed are easy to spot because you’ll see empty cell “gaps” surrounded by capped cells. The tell-tale sign is when you see the removal in action. Before the infested pupa is completely removed, they are first uncapped. The uncapped cells are also easy to spot because you will see the white pupa heads stand out next to the brown wax background. below is a video that shows an uncapped pupa cell and the pupa after we have pulled it out. You’ll notice the varroa mite clinging on to the pupa. The video quality is not great due to us using a cell phone camera and the sun being right over us. However, you can still clearly see the uncapped pupa being removed and the mite attached to it right at 11 seconds into the video.

Below are still pictures that show the uncapped cells and the pupa that we remove from them:

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Notice how the white pupa stands out in the brown background

In the picture below, you’ll notice all of the “gaps” in the brood. Some beekeepers may mistake this as a bad queen with a spotty brood pattern. But most likely those are pupa that have already been removed.

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Notice the cell gaps that appear to be a spotty brood pattern

Varroa mite1

We did a quick experiment on the hygienic hive as well. Out of 10 cells that had been chewed open, 8 of them had a varroa mite. We can assume that the bees were at least 80% successful at identifying worker cells infested with varroa.  However, we have no way of knowing if the varroa mites of the other 2 cells had already crawled out before we found that the cell had been chewed open. So the success rate could be (likely is) higher.

You’ll notice in the video above that there is a bee with deformed wings crawling around. That is indicative of the fact that varroa has been present and has infected some bees with Deformed Wing Virus. What makes a “good hive” is not that it is free of varroa, it is the fact  that they know that varroa is present and are doing their best to address the issue. This hive in particular has begun aggressively removing infested pupa as is indicative by the empty cells in the brood chamber (click here to see my post on hygienic bees that deals with this behavior in more detail) as well as the uncapped pupa that we removed ourselves. When we see a hive expressing this much hygienic behavior, we are confident that they will survive on to next year. They prove this year after year and it’s what we call our “survivor bees”.

Those of us beekeepers who open mate our queens have to constantly monitor our hives and cull out any that don’t make the cut. Since our queens are free to mate with whatever drones they choose, their daughters aren’t guaranteed to be as good as the mother. Your best survivor queen can mate with terrible drones and produce terrible daughters. But realistically, good queens produce some good daughters and it’s our job to propagate only the good ones.  In this manner, breeding for varroa resistant bees is a constant ongoing process. Unless we move our bees to an island or instrumentally inseminate our queens, this will continue to be our struggle as beekeepers. The good news is that if you do this long enough, it gets easier and easier as your apiary (and the feral bees around you) develop a “regionalized” varroa resistance.

There are a few traits that we have identified that tell us right away whether a hive will be a survivor or not (Most of them aren’t seen as qualities from a beekeeper point of view).  Maybe I’ll cover that topic in a follow up blog. But for now, we feel good about the status of our bees heading into the fall. We got through approximately 50 hives before the heat made us throw in the towel and we didn’t notice any other hive that showed signs of a severe varroa infestation. It doesn’t get better than that.

Hygienic Bees

varroa on bee
A varroa mite sucking on a bee. If left untreated and if the hive cannot control the infestation, the hive will collapse. Survivor bees are better at dealing with varroa.

If you are a new beekeeper or looking into becoming one, you’ve probably already heard about Colony Collapse Disorder (CCD). When a seemingly thriving hive collapses suddenly, it is said to have suffered from CCD. However, there is no clear cut symptom or disease that can be identified as the culprit of CCD, but there is a very clear front runner. The front runner would be the Varroa Destructor, or Varroa mite. The varroa mite’s natural host has been the Asian honey bee (apis cerana) and it has just recently (circa 1980’s) evolved to parasitize the European honey bee (apis melifera). The European honey bee and beekeepers were completely caught off guard by the varroa mite and it’s the reason why there are so many resources being spent to study the mite and develop methods to control it.

There is tons of information online about the varroa mite, so I won’t explain its biology in great detail. Think of the varroa mite as a bee tick. The varroa mite will enter the hive, latch on bees to suck their blood, and parasitize the brood. After the mite has fed itself and its new babies on the bee brood (in pupa stage), the new mites will emerge with the new (weakened) bee and begin the cycle all over again. Using this reproductive method, the varroa mite can reproduce much faster than the bees, which leads to massive infestations within the colony. But wait that’s not all, the varroa mite is also a vector of bee diseases such as deformed wing virus. Deformed wing virus is easy to spot as the new bees suffering from this have deformed shriveled wings.

apistan
Apistan is a widely used chemical treatment against varroa

So what are the solutions being developed to control the mites? The first and most effective is the chemical approach. There are a few very efficient synthetic miticides that are currently being used worldwide to control the mite. If you’ve read our section on “our philosophy” you know that we are not fans of the chemical approach as the chemicals undoubtedly end up on our honey. So let’s concentrate on the “natural” or biological approaches.

The first natural approach that I’d like to cover is the “natural” or “small” cell approach. The idea behind this approach is that we need to get back to a more natural brood comb cell size (4.6mm – 4.9mm) and away from using “standard” wax foundation that has a cell size of 5.4mm. The idea is that bigger bees take longer to develop and therefore give more time for the varroa mother to lay more eggs. So by cutting down the amount of time that it takes a worker bee to develop also cuts down the amount of viable varroa mites produced in that brood cycle.

Cell size 4.8mm
We measured brood comb from a feral beehive that we captured. On average, the cells were 4.8mm in diameter. We have seen cells as small as 4.5mm.

I know that there are a lot of proponents of the small cell approach and I think that it has some merit. The issue with most beekeepers is that this solution is not very practical, mostly because it requires going “foundationless” which means allowing the bees to make the cells whatever size they want to make them and not using a sheet of wax foundation with predetermined cell sizes (most commonly 5.4mm). Recently, there have been a few manufacturers that started producing “small cell” foundation at 4.9mm, even so, for reasons I will not discuss here, this is still a more cumbersome approach, especially for the novice beekeeper. There is also very little scientific evidence that this approach actually works. We have experimented with small cell and still have hives with small cell foundation but we typically see little difference in survival rate compared to hives on “regular” foundation. To us, this is an indication that genetics is more important that cell size when it comes to controlling varroa infestations. Having said that, we have measured quite a bit of brood comb from feral beehives and can attest to the fact that the “natural” sized cells that they are building is between 4.5mm-5.0mm.

The second natural approach is breeding bees that can cope with high varroa infestation levels (and the diseases they carry) or bees that can limit or interrupt the varroa breeding cycle. So far, much effort has been put into breeding “hygienic” bees that can detect varroa mites in capped brood cells and remove the bee pupa before the varroa mite can reproduce. This seems to be a very promising trait and it is one that feral bees are already using to survive. We have seen varying levels of this hygienic behavior in our own bees. Most hives that have this hygienic behavior seem to control varroa and it doesn’t appear to bother them too much.

cells chewed open
It is not natural for bees to uncap brood once it has been sealed.  However, hygienic bees can detect varroa and uncap and remove the pupa. 90% of the time, if you pull out an uncapped pupa, you will find varroa.

We have also witnessed beehives that survive severe varroa infestations by doing a few interesting things. First, the queen will stop laying eggs. This means that there will be no new brood and if there is no new brood, there is no host for the varroa mite to reproduce. Secondly, the bees will begin to sacrifice the pupa that they determine have been infested by varroa. This is very interesting behavior because the last thing the bees want to do is sacrifice the pupa that they have spent so many resources to rear. Not only do they waste resources, but they also lose their next generation workforce. In a way, the hive enters a controlled “self-destruction” mode where they have to harm themselves in order to harm the varroa mite. Lastly, the beehive will rapidly collapse in population, probably because of the die off old bees that aren’t being replaced by new bees. After a few weeks of this self-destruction mode, the varroa mite is flushed out (mostly) and most beehives seem to bounce back.

IMG_2694
The white/gray flakes on this bottom board are dried up varroa infested pupae that the bees have removed from their cells. This hive suffered a severe varroa infestation, but managed to recover.

This behavior typically happens in the fall when varroa infestations are at their worst. It really helps if there is some forage available for the bees to produce at least one cycle of new brood to enter winter with a fresh batch of young bees. Luckily for us, we do not have harsh winters in California and the bees usually have some forage available even in late fall.

It really seems like hygienic bees have the best shot at beating back the varroa problem. For this reason, many research institutions and breeding programs are focusing on breeding this trait into their bee stocks. Here at Estrada Farms we don’t have the resources to monitor infestation levels in beehives year round or to instrumentally inseminate virgin queens to precisely control genetics (yet). We simply rely on the tried and true principle of survival of the fittest. This approach has been working well for us, to the point that we largely stopped taking calls to collect swarms or remove bee hives for a few years due to not having room for them; however, we recently secured another bee yard and will resume collecting survivor bees. We have seen it time and again that these feral survivor bees have a few tricks up their sleeve to control varroa mites, including being hygienic.

If you are looking into buying a beehive, ask the beekeeper how they control the varroa mite. If the answer is through chemical treatments, I would not buy from them. There are plenty of beekeepers that are now raising hygienic bees (to some extent) and we need to support those that are moving in the right direction. If we do this, the varroa mite and its problems will soon be a thing of the past.

If you have any questions about our bees, feel free to contact us.