How to use a double-screen (Snelgrove) board

What is it?

A double-screen board is about 1-inch deep with an opening in the center. The center opening is covered with screens on both sides so that bees on one side of the board cannot contact bees on the other side of the board. It often comes with openings in the rim that can be toggled open or closed. These are in pairs (an upper and a lower) on each side of the board. Some boards have a total of eight openings, some have just six.

This piece of equipment is also known as a Snelgrove board, after L. E. Snelgrove who used it to control swarming. His method—a bit complex—is a subject for another day. However, there are many other uses for his clever invention.

How is it used?

1.  For queen introduction

1.1  When introducing a new queen to an especially strong hive, pull a frame or two of emerging brood and a frame of honey out of the brood chamber and replace them with empty comb or foundation. Remove the old queen.

1.2  Place the double-screen board on top of the chamber

1.3  Place another box containing the emerging brood, honey, and the caged queen on top.

1.4  Open one of the back entrances so the newly emerged bees can come and go.

1.5  After a few days, release the queen in the upper box.

What is the benefit? Newly emerging bees will be more accepting of a new queen than the old foraging bees. After a few more days you can close the back entrance and open the front two. This way the bees will slowly start to mix. After a few more days you can remove the double-screen board completely.

2.  For combining two hives

2.1  Place the double-screen board between a queenright and a queenless colony before combining to allow them to adjust to the new scent.

2.2  Open an entrance to the top box on the back.

2.3  After a few days, close the back entrance and open the two front entrances to allow the bees to mingle. Later, remove the double-screen altogether.

What is the benefit? It allows the scent of the queen to circulate throughout the boxes before the bees can come in contact with each other.

3.  For over-wintering a weak hive

3.1  Place a double-screen board above the brood box of a strong hive and then put a weak hive above it.

3.2  Open one of the entrances so that the bees from the weak hive can come and go. This entrance should be on a different side than the entrance for the lower (stronger) hive.

What is the benefit? In this way, the weak hive gains the benefit of the warmth from the hive below, but the hives remain separate. It improves the chances of winter survival for a weak hive that might have trouble keeping warm.

4.  For moving a hive in hot weather

4.1  If your bees must be confined to the hive in hot weather, fasten the double-screen board on the top of the hive in place of a solid cover. Nails or screws can be used, but screws do less damage.

4.2  Make sure all the toggle entrance are closed.

What is the benefit? This is basically the same as a “moving screen” which provides extra ventilation to bees that have limited ways to keep the hive cool.



  • Hello !

    on this page :

    you write :

    2.3 After a few days, close the back entrance and open the two front entrances to allow the bees to mingle. Later, remove the double-screen altogether.

    How do the bees intermingle? Is it because the two front openings are close to each other? I have an LW hive which is strong, and a queen right swarm I extracted from deep in a vent and numbers are down.

    So, I bought a double screen board. Oddly it only has 6 openings (none in the back). So I will somehow cut a back opening. When back opening is closed and front is opened, the bees are able to find the new opening in the front?

    It was suggested that after I go through the steps and remove the DS board, I should put the queen in a 4″x4″ cage on her brood (1 board) for a few days AND use newspaper between the two hives. But I thought maybe since I have used the DS I perhaps may not have to do those steps? I guess I could still get the queen in a cage for a few days just in case.

    Great site !! Thx.

    Doug Fairclough

    • Doug,

      When you close the back entrance, the bees in the top box will begin leaving by the front entrance. When they return, some will use the entrance that leads to the top box, and some will use the entrance that leads to the bottom box. Thus, they slowly mix, and since air has been flowing between the two boxes through the screen and distributing the queen’s pheromone, no alarm signals will be initiated.

      As I said in my article, many double screen boards only have six (not eight) openings, so you can use a side entrance instead of a back one. It doesn’t matter. When the new entrance is being used, bees will stand by it and fan their Nasanov glands so the other bees will learn where the new opening is.

      I’ve never used a queen cage after using a double screen nor would I use newspaper. You have to trust the screen to do what is was designed to do. If I didn’t have a double screen board, then I might use one of those other techniques. Just because there are multiple techniques available doesn’t mean you have to use them all at once–just pick one and go with it.

      My only concern with your question is it sounds like you have two queens. Do you have two queens or have I misunderstood?

      • That makes total sense to stick to one technique and not jumble them; in this case, to trust the double screen board approach.

        I have a very small queen right colony that I extracted from deep in a stove vent; they had been there a bit and numbers were down. Plus, the queen was a probable virgin queen – small and I saw her return from a flight a few days after I had settled them into a NUC. Strange to see the queen stick a landing and walk on into the entrance! I waited a few weeks for the queen to start laying on a brood board I had added from another hive to give them a boost.

        The second hive is a lot bigger, an LW hive that had a lot of the resources that I felt the smaller colony could use. I got the laying to stop while I was waiting for the stove vent queen to start going.

        So it seemed like a good combination of hives to.. combine.

        At that point I came across your article, and the DS board seemed more controlled than using newspaper or a queen cage.

        I followed your prescription and removed the DS board yesterday.

        Thx again for the article and the clear instructions on how to proceed. I’ll post an update. One thing I’m wondering is how long it will take the queen to move down into the deep of the LW hive, which is wide open in terms of space in which to lay.


        • Doug,

          It shouldn’t take much time at all. A few minutes, a few hours, for a queen to move down. If the comb has been prepared for her, she will be looking for it.

  • Hi Rusty. This double board sounds like a very useful tool. I have 2 first year hives now experiencing their first Michigan winter. And it’s starting out strong. The winter that is. I am worried about one hive being a bit weak. The colony had a lot of weight in the fall but just a month ago it seemed much lighter and the activity does not match the stronger hive.

    With our 20 something degree days we are in, is it too late to try and stack the weaker hive on top of the stronger with a double-screen board between them?


  • Rusty… I finally gout out to check my 2 hives. I tipped up the outer cover and quilt board (based on your design) as a single unit and to my surprise each hive had a thick cluster about 10″ in diameter on the top bars. No idea how deep into the frames it went. I hope alot.

    So with a month of below freezing temps, many in the single digits, I am pretty pleased. My only concern is that they are right at the top of the stack. Should I be concerned about that?

    Thank you!

    • Frank,

      Bees on the top bars usually means they have eaten through their food supplies. Feed them solid feed (hard candy, fondant, or granulated sugar) as soon as possible. If you get a warm day, you can open the hive and rearrange any honey frames so they are close to the cluster. In the meantime, feed them right away.

  • Thanks Rusty. I have one medium super of Buckwheat honey that is about 80% full in reserve. I could split that between 2 mediums, add drawn but empty frames to fill out the sides and put one on top each hove. Sound good?
    Plus feed too?
    The honey has been out in my unheated shop so maybe I will bring inside for a couple days to watm up first?

    • Frank,

      You have a medium super of buckwheat honey in reserve? I would kill for a teaspoon of it! Damn, do I ever miss buckwheat honey.

      That aside, yes, your plan to feed back the buckwheat honey is perfect (but sad . . . sigh). You can wait on sugar supplements, but do check on them periodically to make sure they have enough. Warming the honey isn’t necessary, but it won’t hurt either.

      • I am sure I will get more buckwheat next year and I would be happy to send you some. A small thanks for the wisdom you share freely here.

        I made up some 1.5″ ekes yesterday and I also made up sugar cakes last night. I going to give them a cake each on top of the buckwheat.

        Interestingly, this past August I planted a 10’x12′ patch of buckwheat just 75′ from my hives. I saw all kinds of bumbles and other bees on it but never saw a single honeybee on it. Not even in the morning. But I got about 8 medium frames of it in September. They got it from somewhere. Personally I didn’t care for the taste. Kind of molasses flavor with a sourness at the end. Beautiful molasses color too. I assume it is buckwheat honey.

        • Frank,

          I think most people don’t like the taste, but it’s the only kind I had as a kid and it’s by far my favorite. Your description of the taste sounds exactly right. Have you read my post Cemetery Honey?

  • Haha . . . you gave me a good chuckle. I just read “Cemetery Honey” and now I see why buckwheat is your favorite. It’s safe! Great story, Rusty. I really need to get you some of that safe honey now.

  • I have a strong hive with a superseger queen cell. Can I use the double screen board to make a split and put the queen cell in the top and the old queen in the bottom? And after the new queen emerges, I will put the top in a new hive. Will that work? Thanks

    • Brian,

      That will work if you end up with a queen in both hives. But if it really is a supersedure queen cell you are seeing, the old queen may be failing and they may be replacing her for a reason. Pay attention if you do this.

  • Hello Rusty,

    I’m interested in the double screen board as a possibility for overwintering a weakish hive on top of a stronger one. One of my hives definitely would be a candidate for this treatment, as it’s numbers are quite low. However, I’m also wondering if it is too late to simply requeen (today is September 6, and where I live we have weather in the 50s/60s till early October, though frosts most nights beginning in mid/late September). I’ve never requeened in the fall, though I think it’s not uncommon. In your opinion, should I try it? I’ll probably build a double screen in any case…it sounds like a very useful tool when needed, and this year may be the time it’s needed!

    • Sarah,

      You can certainly re-queen now but you will probably wind up with a small winter colony anyway. It’s just that time of year. If you think your current queen is weak, re-queening now can give you a better build up in the spring.

  • Hello Rusty,

    I plan to use the Snelgrove board to put a queenless hive on a queenright hive. Both hives are in my apiary. How do I encourage the bees in the queenless hive to reorient to the new hive? I’m worried about them going back to where their hive was and getting lost. Should I keep them closed up for a day or two?

    Thank you.

  • Is there a site that shows how to make a double screen bottom board? I think I have figured it out but would like to make sure.

  • Rusty when you overwintered with the double screen board, did you do anything before or during the first days or just throw on box of weaker brood onto the DSB? What was your whole set-up like?

    I’ve got a 4 over 4 double nuc set going, already up, but also want to try the DSB with another pair of nucs. This will be my first attempt with both methods.

    Thanks a bunch

    • Jess,

      I took the lid of the strong hive, added the Snelgrove board, the weaker hive, a feeder for the weaker hive, and then the lid.

  • I think that a common misconception is that the queen pheromone wafts through the air and completely fills the entire space much like I can smell my wife’s great cooking even though I am upstairs. For bees, the pheromone is transmitted not in an aerosol fashion but rather molecule by molecule by her attendants. Attendants physically touch her with their antennae and feet and I suppose other parts and then as they move around the colony, her pheromone smell molecules go with them and are thus transferred to others. But when the double screen is in place, the attendants cannot get even a single molecule to those bees upstairs because of the gap between the two pieces of screen. They might stick their proboscis or antenna up through the first screen, but it never reaches the bees up above. As a result, the upstairs bees soon feel as though they are queenless because of the sudden loss of pheromone molecules in their neighborhood.

  • I used a double-screen board this year for the first time. I worked with two other guys on a queen rearing project, just to see what we could do by way of not having to buy queens. I ended up with a booming queen from one and the other I think didn’t make it back from her mating flight(s).

    I put the weaker colony above the stronger one and used the toggles to mix and move bees up to the top hive. Open a toggle from the bottom hive in the morning and let them get used to that entrance. In the afternoon close the bottom toggle and open the top. They go to that side and enter the top hive, I guess thinking it’s the same hole they left from or something.

    Coming into the fall I took a full medium super and put it between the hives with a queen excluder above and below, pollen patties and a syrup feeder on top. The workers move freely up and down but the queens are separated by the super in the middle.

    I’ve also used a slatted rack on the bottom and have a Bee Cozy in wait. I really want this stack to make it through the winter, especially that bottom queen. She fills everything in sight!

  • I am considering moving one hive on top of another to over-winter. Couple of questions/issues.

    1. Why use the Snelgrove board at all? It seems like an unnecessarily complex structure (unless one is following Snelgrove’s equally complex instructions to “prevent” swarming). My hives are on screened bottom boards – wouldn’t it serve the same separation purpose if I just moved the whole structure (obviously, in under the other hive’s lid)? That is, Strong Hive living quarters — Strong Hive feeder — Strong Hive inner cover or not? — Weaker hive living quarters (complete with bottom board and their own front entrance) — Weaker hive feeder — Final inner and outer covers?

    2. Assuming this is plausible, it presumably would be better to orient the upper hive with their entrance on the opposite side from the main hive. The ladies in the weaker hive have been running a lot of orientation flights lately. What the heck are they thinking? and will they be OK? I know, I know – cork up the entrance for a couple days, put some trash in front when I do re-open, and hope for the best. Plus they’d be facing north rather than south, so it ought to be pretty obvious even to the most clueless forager. Just say something re-assuring 🙂

    • I guess I don’t understand exactly what you’re asking me. You can stack colonies any way you want, that’s up to you. The double-screen board is not complex in my opinion, it has multiple uses, and you can orient the entrances any way you want. But if you find that objectionable, do something else. Lots of orientation flights can mean lots of brood is emerging, which is a good thing, right? And I wouldn’t worry about reorienting in winter. They go out so infrequently, they’re always reorienting.

      • OK, this happens to me alot; I do like the sound of my own voice, even in print. Buried within my musings on Snelgroves was what I thought was a simple question:

        For purposes of over-wintering a weak hive above a strong one (usage #3), wouldn’t any old screening serve the same purpose? Such as the screened bottom board of my weak-ish hive?

        Obviously, I am also aware that I can stack my components any way I want to. I posted here to ask for clarification/advice on a specific sub-topic, rather than rushing out to buy another tool whose other uses are beyond my requirements.

        • Okay, got it. The short answer is simple: the double screen is designed to keep bees from two different colonies out of contact with each other. The space between the two screens is too wide for an aggressive stinger to reach across. You can build one yourself if you don’t want to buy one, and you won’t need multiple doors.

          The slightly longer answer is that if you also have something between the screen and one set of bees, like a quilt box or whatever, then you don’t need to worry about the bees reaching each other and any old piece of screen would be sufficient to allow ventilation while keeping the bees apart.

          Lastly, I think “obvious” is the most dangerous word in the English language. What is obvious to one person, is totally perplexing to another.

  • I used a double-screen board to stack a weaker colony over a strong one, both were the result of a successful queen rearing endeavor. I gave them a few days to get used to each other and then used the different entrances to move bees from the strong lower colony to the upper one.

    I did this by opening the lower door in the morning so the lower bees got used to using that door. In the afternoon I would shut the lower door and open the upper door on that same side. Bees from the lower hive came back to that door and went in the upper hive.

    After a week or two, I changed things up as both hives were used to each other by then. I used a screened bottom board, slatted rack, lower deep, queen excluder, medium super (full of filled frames), queen excluder, upper deep, inner cover, empty medium super (used to house a feeder), and outer cover. I could check the feeder by lifting the outer cover. If it needed to be filled I used a canning jar lid to block off the inner cover and just swapped a full feeder in, then I would fill the empty feeder to swap in on the next hive.

    When I wrapped things up for the winter both hives were looking good. I did a mite check and an OA dribble, gave them winter pollen patty, and put them to bed for the winter. I am trying out hive wrap insulation this winter along with an “Ultimate Hive Cover” type outer cover. On the warmer days, the bees have been coming out for orientation/cleansing flights. Things are looking good so far, we’ll see what the spring brings…

  • ●INEXPENSIVE alternative…place window screening down above the bottom deep frames. Put a queen excluder over it. Put a sheet window screen over the tops of each layer of brood frames. The bees will put propolis on screens to conserve heat over the brood. It’s easy to peel off, easy to reseal the propolis.

    I have 3 queenright deeps on top of each other, weakest on top. It’s starting to get cold. During summer dearth, I took out a frame or two on one side and put a mason jar with syrup on it inside. I put a blue shop towel to wick the syrup from the lid hole. The bees below suck the shop towel through the screen. The bees on top just enter the feeder and lick syrup. I stapled window screen to the entrance so they can easily ventilate as needed. I create a tunnel with a stick vertically. They know to use the vertical tunnel to enter/exit the screen. Robbers don’t. Even if they did, the resident bees don’t have to die fighting. They simply create a traffic jam in the tunnel and the robbers can’t get past. There’s not enough room to attack each other. The tunnel runs vertically, up the front of the hive. Robbers, moths, small hive beetles are stuck at the entrance near the bottom. They don’t know they need to go up and enter through the tunnel gap. Somehow the drones figure it out. They will also wait outside the tunnel gap whining for food. Get a roll of window screening. It solves everything. Use it instead of plastic foundation. Staple to the frames. Cut a triangle gap in each corner. Easy to remove the wax if needed. Just leave a little excess on the sides so you have something to grab and pull on. Use the screen leftovers that had comb or propolis on them in a swarm lure box.

    I got a cheap roll of window screening/porch screen and I use it on my beehives for EVERYTHING. Bees like it. The stapled entrance seems to really keep them calm, less defensive.

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