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The undervalued robbing screen

In my apiary, I consider robbing screens a necessity. Since I began using them about ten years ago, I haven’t had a single case of robbing. Prior to that, it was an annual fight to keep things under control.

This year in particular, I’ve had many beekeepers write in a panic asking how to stop the robbers. But, in truth, it is a zillion times easier to prevent robbing than it is to stop it.

Robbing usually begins in a nectar dearth when foragers from one colony find a hive that is weak or poorly defended. They detect the scent of stored honey inside and try to steal it. Fighting ensues, often with many deaths on both sides. If the defending colony becomes overrun, the marauders are free to take what they want.

Ripped and ragged cells

Robbing bees rip open honey cells instead of opening them nicely, honey flows out of the damaged cells, and the scent of honey is further disseminated. The scent will attract not only more bees, but other predators as well. Both the scent of honey and the odor of dead bees will attract hornets and yellowjackets. Once robbing begins, it feels like an avalanche. Everything gets worse in an overwhelming hurry.

Beekeepers can inadvertently initiate robbing by spilling a drop or two of honey or sugar syrup in the vicinity of the hives. Anytime you open hives in a dearth you are asking for trouble if you don’t take preventive measures.

Following the scent

Both wasps and honey bee robbers follow the scent of the hive. Since they don’t live there, they don’t know where the “door” is, so they sniff around. You can often see robbers examining the area just under the roof, the seam between two boxes, loose box joints, the area under the screened bottom, or any other place where the scent of the hive can leak out. They will keep trying and trying until they find their way in.

Robbing screens work by diverting legitimate hive traffic to an opening away from the real opening. The new openings are usually five or six inches above the main opening, and they are positioned above an impervious surface that prevents the hive odor from escaping.

However, a screen lower down near the “real” opening, allows the scent to escape. The robbing bees detect the scent through the screen and spend their time trying to find their way in. They don’t go near the diverted opening because it is covered by the impervious surface. Once the robbers move too far from the screen, the scent weakens, so they turn around and go back down.

Robbing screens traditionally have two diverted openings that open and close. Normally, you start with one open and one closed. If some robbers manage to find the opening, you can switch them and the learning process has to start all over again.

The first time I used robbing screens, I was skeptical, but they really do work. However, they work best if robbing never starts in the first place.

Use robbing screens early and often

I install my screens just before honey harvest because harvesting can sometimes begin a robbing spree. Then I leave the screens on until the fall when cold weather keeps the bees inside.

However, with nucs, splits, and captured swarms, I use a robbing screen from day one. These colonies are often small enough to get attacked by robbers during early spring or when there is a temporary lull in the nectar flow. I used to worry about those small colonies, but now I just add the screens pro-actively.

Types of robbing screens

A few different styles of robbing screen are on the market, but my favorite is by BeeSmart Designs. They are easy to put on and take off and they fit either 8-frame or 10-frame equipment. They come with push pins for attachment. If you buy the BeeSmart Designs ultimate bottom board, there are attachment points for the screen as well. Best, with the BeeSmart bottom board, the robbing screen can be replaced with a special mouse guard in the fall.

One of the problems with the wooden-framed robbing screens is that if you use a slatted rack, the rack and the lower brood box must be lined up precisely, because wood doesn’t bend around the edges and you can end up with a space at the sides large enough for a yellowjacket. You still need to have things basically lined up with the BeeSmart screen, but I find the plastic is a little more forgiving and easier to use.

Other advantages of a robbing screen

One of the overlooked advantages of a robbing screen is that it keeps out drifting bees as well. This can have a significant impact on varroa control. We know that drifting bees are one of the primary means of varroa dissemination. Drones especially are not very particular about where they bed down for the night, and they can easily travel from one hive to another. And because they’re drones, they’re usually allowed in.

If your colony is already overrun with mites, this might not make much difference. Perhaps you lose a few mites when drones leave, and you gain a few mites when drones arrive. However, if your mites are under control, drifting bees can make a huge difference.

In fact, if you have no mites to start with, one foundress mite can multiply into a sizeable infestation in one season. But if three foundress mites move in, they can produce three times as many mites in the same length of time. Multiple and repeated introductions can overwhelm even mite-resistant bees.

To me, it seems that robbing screens should be part of an IPM program to keep varroa under control. It is an additional technique we can use that is inexpensive, easy to implement, and chemical free. When paired with other IPM techniques, robbing screens can be a useful mite control tool.

Rusty
Honey Bee Suite

Robbing screens on wooden hive.
This hive has a BeeSmart bottom board, hive cover, and robbing screen. This was a split where I left the robbing screen on all year.
This hive contains a swarm that moved in this past spring. I left the robbing screen on all season, but when the colony got large, I opened both entrances.

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Comments

MarianA
Reply

How do the bees get the dead out? Are they able to haul the bodies up to the opening for disposal? I’ve had problems with closed-bottom robbing screens–they had trouble cleaning house.

Rusty
Reply

Marian,

The bees can carry the dead out, just like they do when they’ve only got a top entrance.

Ken
Reply

Thanks Rusty, I have been thinking about robbing screens for a while now. I have a weak colony that is now awaiting a queen cell to yells a queen. This helped me to be decisive about a robbing screen for it…and soon!
Maybe I will put them on my other hives right before I harvest.

Good ideas, please keep posting them.

Ken

Mike
Reply

Rusty. Interesting article. Begs the question – can’t figure out from the pictures – is the hive opening the usual full width across by 1/2″ or so to start? So this covers the whole opening and forces the bees to find a new entrance/exit up at the top? Maybe you mentioned but needs to be put on in the morning before the workers leave or they won’t find the new entrances? Sorry for my confusion. This time of year I’ve usually constricted my entrances down to 1/3 opening to hope keep out yellow jackets. Mike

Rusty
Reply

Mike,

No, I have entrance reducers on under the robbing screens. I think some people take out the entrance reducers, but I think if robbers are bad the first line of defense is the robbing screen. If some of the robbers get in, the second line of defense is the reduced entrance. Most of my hives are reduced to about three inches and then the robbing screen added. I never open the entrances all the way across.

As for putting them on in the morning, that’s what the instructions say. But I put them on any old time. Once one of the bees finds her way in, she will fan the rest in with pheromones. So I don’t do what the directions say on that.

Bill Abell
Reply

Hi Rusty,

I also keep robbing screens on all year. Robbing is one of the biggest threats any colony faces in an apiary with hives in relatively close quarters. Yellow jackets and other wasps and hornets have been bad for me this year and I am very grateful for the robbing screens. I make my own out of scraps 3/8 or 3/4 inch plywood and #8 screen. I have the one small 3/4″ entrance at the top left side and a larger 2-3″ on the bottom right which is closed or reduced most of the time in the spring and summer. But during our May and September nectar flows, I leave both open. If you spot a problem it is easy to close up the hive until everyone gives up and goes home.
As you said they really work.

IslandLife
Reply

Whatever we (readers) get to glimpse of them, your hive stands are beautiful, functional, and seem sturdy and well made … Inspirations for sure.

Rusty
Reply

Thanks, Paul. That’s because they’re built and designed by a mechanical engineer!

Kaz
Reply

Hi Rusty,

Thanks once again for your valuable info, I’m always learning from you. 😀
I’d love to replace my current DIY robber screens with these, but can’t see to find a stockist in Australia, and shipping costs from US seem very high. Do you know of any stockists nearer or in Oz. Cheers Kaz

Rusty
Reply

Kaz,

I’m sorry but I don’t know of any. This product is fairly new and it will probably take a while to get better distribution.

debbie
Reply

Hi Rusty,

I have the same thought as above, I can’t figure out from the pics where the entrances even are!

I, too, use robbing screens all year round. I use the wooden w/the screened front, but over the screen I usually add house screening so that the bees cannot feed each other thru the mesh. In the past, I have seen robbing bees feed each other thru the mesh, so that is what prompted me to add the screening. On the nucs, I too use both, the entrance reducer and the robbing screen and use the top entrance when the nuc is young and convert to the bottom entrance as the nuc strengthens. One way people can tell for sure if robbing is going on, is by looking at the bottom board, if it has wax pieces all over the place, then you know that the bees are uncapping that honey. Also, I try to take most of the excess honey off of the hive before robbing season starts, and then put it back toward the winter maintenance “bedding” time. This way, it reduces the aroma of the hive a bit and keeps robbing to a minimum. Oh the joys of beekeeping ! Thanks for this posting, I think people under value the uses of robbing screens. I leave them on all year long except on the huge mass producing hives that can pretty much take care of themselves!

Rusty
Reply

Debbie,

If you follow the link you can see a good diagram of the robbing screen.

I agree that harvesting before the dearth is the best alternative.

Ollie
Reply

I plan on harvesting honey in mid September. Should I reduce entrance and put robbing screens on after harvest? Should I leave them on until spring?

Rusty
Reply

Ollie,

I usually do it before because harvesting can start a robbing incident, but that’s up to you. There’s really no reason to leave them on during winter. In winter mouse guards are more important.

Linda
Reply

Hi Rusty! I am a new beekeeper (started in May with two hives) and I have a couple of questions about robbing screens. Is this something you use only when you have multiple hives? I live in NC and wondering when “robbing season” is? Just during the nectar dearth? Thank you! I love following your blog – so much useful information for a newbie like me!

Rusty
Reply

Linda,

Robbing honey bees can show up from hives a mile or two away, however the closer they are, the more likely is a robbing incident. Yellowjackets and hornets can be close by, too.

Sandy
Reply

Great info thank you.

RandyKeel
Reply

What does that do for good ventilation? In the summer don’t you need openings in the top too? Here in Virginia Beach it’s kind of hot.

Thanks for all your info,

Randy

Rusty
Reply

Randy,

You can use robbing screens along with screened bottom boards, screened inner covers, and screened ventilation ports. Your options for ventilation are endless.

Trudy
Reply

I like my robbing screens too. Never thought of it being used as a mite control.

Kevin
Reply

Hi Rusty (& everyone else),

Four years ago, I came across this article by Dr. Eric Mussen, UC-Davis, on robbing: http://entomology.ucdavis.edu/files/147611.pdf . I made four of the screens and they seemed to work as I haven’t had a robbing incident since. I’ve seen the occasional yellow jacket get in, but I see the bees take care of the intruder. This year, on a somewhat weak colony, I noticed some marauders getting in, but I solved this problem (seemingly) by reducing the entrance.

I have a picture of an even simpler robbing screen, but don’t know how to post it. I can email it to you if you wish.

Lucinda McCartney
Reply

How does one distinguish between robber bees and the girls who belong there. I am a first year beekeeper and bewildered by it all.

Boyd Young
Reply

Do you ever concern yourself with a robbing screen that covers the top entrance in the inner cover?

To stop robbing, I’ve put on a mouse guard over the top of an entrance reducer. Then added a very small piece of tin between the two reducing the entrance down to 2 openings for smaller colonies, and 3 or 4 for larger colonies. The round openings can be blocked by a single guard bee. It will create a bit of a bottle neck, but the additional bees at the opening seems to discourage the robbers from thinking about it. As the robbing stops, I increase the number of holes available till the number of bees at the bottle neck decreases.

Rusty
Reply

Boyd,

I like this idea and it’s a good way to transition between robbing screen and mouse guard.

As for top entrances, I remove them when my honey supers come off.

Darlene
Reply

Can you comment on when to put robber screens on vs mouse guards? I have robber screens on now but I was recently told that mouse guards should be on now as our nights are starting to get cooler. I recently purchased new mouse guards that are metal with 3/8 inch holes. I was considering using both if they fit after reading that you keep entrance reducers on. Your thoughts?

Thank you for another perfectly timed post.

Rusty
Reply

Darlene,

I put mouse guards on when the bees begin clustering to stay warm, but you can use both. See the comment below by Boyd Young.

Mikey N.C.
Reply

Rusty,

You said that they work really good with their bottom board. How do they work with standard SBB?

Rusty
Reply

Mikey,

They work fine with a screened bottom board (SBB) or a solid bottom board (SBB). If you look at the last picture, you will see mine used with a screened bottom board.

Mikey N.C.
Reply

When using year round do you use a top entrance when you’re in a heavy flow? Also do you use any type of top ventilation?

Rusty
Reply

Mikey,

1. I have a top entrance drilled in each honey super.
2. I use screened inner covers for upper ventilation.

Craig
Reply

Rusty,

Just curious. When you use that BeeSmart bottom board, have you noticed any increase in washboarding/linedancing?

One of the theories on why bees do that is that they’re polishing the surface of the wood. Since that bottom board seems to have a textured surface, it might either confirm or dismiss that theory to some extent. If they want things smooth, they’d most likely be line dancing their butts off.

Rusty
Reply

Craig,

No, I haven’t seen any increase. One hive had a lot of washboarding this year but they did it on the front of the wooden brood boxes, above the bottom board and robbing screen.

Mikey N.C.
Reply

Thanks for info. Here in the southeast bearding and fanning can cover the entire front of hive.

Rusty
Reply

Yes. Here too.

Dave
Reply

Hi Rusty,

I’m from the UK and all my hive floors are the same dimensions as the brood boxes etc. Unless I pay the high price of international shipping I cannot get a plastic robbing screen. My question is the wooden screens mostly seem to have the bottom corners cut out so to fit snug with the hive floor, this looks to work only with floors that extent out from the bottom of the brood box, do all US floors extend out like the ones in your pictures?

Rusty
Reply

Dave,

I don’t know if “all” US floors extend out beyond the brood box, but you can make a robber screen out of a piece of hardware cloth.

Anna
Reply

Saw these robbing screens on an earlier post of yours and decided I may prefer these over the wooden ones I normally use (which warp in the rain). So when I was at EAS I snagged a couple to try and I really, really, like them. Very easy to install and won’t warp!

In my apiary I’ve not been able to feed nucs or small colonies for years due to robbing. I’ve had to feed the large colonies and then give the filled frames to the smaller colonies.

Something I’ve wondered: if all of the colonies have robbing screens, don’t the potential robbers (who also come from a colony with a robbing screen) figure it out? I guess if they use scent to locate the entrance of an unfamiliar colony rather than prior experience (of their own robbing screen), it can work to have screens on all of the entrances.

Rusty
Reply

Anna,

I like your idea of feeding the large colonies and then transferring filled frames. That’s a clever idea.

I too have wondered about all the hives having similar entrances, but apparently bee learning is not like human learning. Apparently they go by smell regardless of what they “know” about the doorway arrangement at home. But yes, it seems odd.

Michelle Wolfson
Reply

Hi Rusty,
I’m just about to move my apiary around 120 kms. I was going to close up the entrances with f/g screen and duct tape just before the move but I’m wondering if I can get double duty from these robbing screens by just closing both entrances for the trip. I haven’t decided if I’ll move the hives pre-dawn or post-dusk but I’ll strap and spline the hives first. Your thoughts?

Rusty
Reply

Michelle,

Yes, robbing screens would work. In fact, they are very similar to what are called “moving screens.”

Amy
Reply

Hi Rusty,

Since having a couple robbing incidences I also use the screens sometimes, but I also always reduce the entrances to 2-3 inches using house screen. Thank you for the great article.

Question: From looking at the picture, I wonder, do you overwinter in a deep and a medium?

Rusty
Reply

Amy,

Yes, this year I’m going to winter in a deep and a medium.

Steven (Melbourne, Australia)
Reply

Hi Rusty, I know this has briefly been addressed above, and I really like the idea of the robbing screen, but it seems trash is accumulating at the entrance and bees are not carrying it up and out. It’s the end of winter here now, so no dead bee material, but they are carrying out sugar that I put in the vivaldi board feeder. That is accumulating at the entrance. Any thoughts?

Rusty
Reply

Steven,

You could just remove the robbing screen and sweep away the debris. I often clear the bottom boards at the close of winter regardless of whether I use a robbing screen.

Jackie
Reply

I checked out BeeSmart Designs for the robber screens but didn’t see them for sale. Another source?

Rusty
Reply

Jackie,

The links in the article take you straight to Blue Sky Bee Supply, where you can purchase the robbing screens.

Anna
Reply

Jackie, I talked to BeeSmart at EAS and told him the screen was not on his website and he said it was hard to keep the site up-to-date with new products. Use the link Rusty provided.

Lisa
Reply

Hi Rusty,
The first time I saw a wasp land on a super I had just set aside, I realized how open and vulnerable that box was while the rest of the inspection was taking place. I began as a habit now to bring 4 of those plastic sign boards with me and offer protection by placing one on the ground, then my first medium which is promptly covered with a sign board. So is the open hive top. This gives me time. I can decide to inspect either. Bees are contained, not flying at me, and everyone is safe always. I can pry off the next box and set it on the sign board thats on the first box, then cover it with another. It works so well, why have I never heard of anyone else doing it?
Only my 2nd year… Lisa

Rusty
Reply

Lisa,

Many people use pieces of canvas to lay over the open boxes. I’ve heard them called inspection clothes, manipulations clothes, draw quilts, and other names. I use screened inner covers or just pieces of cardboard. They all do the same thing.

debbie
Reply

Rusty, Thank you for the link. They are nice robbing screens. I will order a dozen of them to try out. Covering boxes as they are removed is an excellent idea I have used for years now. It sure keeps down on the bees flying around and it keeps them much calmer. This is a great post with some great ideas. Thanks again !

debbie
Reply

Another thing I like about this screen is the bees cannot ‘see’ through the front …. and it only has two entrances on the top. An improvement over the wooden/mesh screens. I like ! Thanks !

Ginny McVickar
Reply

Rusty,

I am in a predicament. Due to our severely dry summer (wildfires and high temps) I began feeding bees. Robber screen is in place yet I thing they are still being robbed. Entrance is reduced to one small 1.5″ opening and my own bees I think have backing up traffic coming and going. Front of screen, I believe, is covered with robbers altho they won’t tell me they’re robbing. There are fights. Should I stop feeding 2:1 syrup in upper most super that surrounds the feeder? I don’t have a second upper entrance because of robbing. Would it do any good to cover the screen where the small entrance is visible? What makes the robbers leave? Do they smell the sugar formula on my bees? Any comments and suggestions gratefully appreciated.

Rusty
Reply

Ginny,

Are you sure it is robbing and not drone eviction? If you’ve reduced the entrance and are using robbing screens, there isn’t much more you can do. Don’t use any essential oils in your syrup, though. That would make it worse.

Alan Montgomery
Reply

Hi Rusty;

I am in eastern south dakota and my buuy has his bees about 75 yards from my four colonies. I had 4 medium supers on two of these colonies. The supers being older had a few openings on corners etc. Today the bees from his Warre hives were robbing mine. I don’t know when it began but it was in full swing. I duct taped all possible entry points. I had planned to put escape boards on to remove in morning but hesistated now. What should I do? I ordered four beesmart robber screens. Should I go ahead this eve and place the escape boards and reseal for the night? I thought to remove two supers at at a time, or should I go for all four on each now? Or should I wait leave them sealed up for a week until robber screens get here? I would like to start feeding 1:1 syrup with fumidil soon. Thanks Rusty!

Rusty
Reply

Hey Alan,

There is no perfect answer. If it were me, I think I would go ahead and try to remove all four supers at once. It might take them longer to empty out, depending on how many bees are hanging around up here. But every time you reopen the hive is like reopening an old wound. Certainly you won’t start robbing by putting in the escape boards because it’s already started. So I would just go ahead and do it in the evening when the robbing slows down.

Just be really sure everything is sealed or the robbers will get in the supers and with nobody to defend, the supers could get emptied out in a jiffy. Maybe there’s a better way, but that’s my gut feeling about it.

Alan Montgomery
Reply

Hi Rusty;

Today was 86. Tomorrow 65 for high and 40 low. Same again tuesday. Then a steady rise into mid 70’s rest of week. So do you think I should try pulling the supers on the next couple days? Then install robber screens?

Rusty
Reply

Alan,

Okay, I didn’t see this comment before I answered the last one. (I see them in reverse order, which is weird sometimes.) Anyway, yes. Temperatures of 65/40 are good to work with, and with 40 at night, the supers may empty over one night. So yes, get the supers off before it gets warm again, and then install the robbing screens as soon as you get them. That way, you can get on with your syrup, etc without waiting.

Alan Montgomery
Reply

Hi Rusty;

Ah yes thanks! This makes sense. To be honest I have not ever used robber screens in over 20 years of beekeeping😊

Best,

Alan

P.S hope there is some honey left 😭

Rusty
Reply

Alan,

You probably didn’t have your friend’s warre bees chompin’ at the bit, either!

Alan Montgomery

Yeah that is true. He was worried they would not compete with Langstroth hives which were overwintered large colonies. One a survivor queen from Old Sol in Medford OR. But I did ask that he maybe relocate them for a little while to allow mine to bounce back. Heading out in cool morning to place the escape boards. Wednesday morning 40f.

Alan Montgomery

Hi Rusty;

So truth be told upon investigation this evening I opened the hive that seemed more troubled with robbing. About half the honey in the supers. I dug down into the brood boxes…cleaned out. The bottom box had about 8 or 9 queen cells some capped some open. No bees except robbers. That was a really strong hive with no indication of swarming at least 3 weeks ago. Well I added hopguard strips for varroa control two weeks ago. This was the survivor hive with the survivor queen. Gee, wonder what happened this late in the season. The robbers were cleaning up the mess. Wow. What’s your take?

Rusty

Alan,

Wow. That is so sad. But I know robbers can make quick work of honey stores, so it doesn’t surprise me. Other than that, it’s impossible from here to know what happened. It’s possible robbers killed the queen, but it sounds like maybe she was weak for some other reason. I never had an issue with queens and HopGuard, so I doubt it’s that. Did you notice a lot of mite drop from the treatment? Maybe there was a high virus load in the hive.

Alan Montgomery

Hi Rusty;

Actually I had not noted the mite count. I was about to place a screened dadant bottom board on tbis one. The bottom board was littered with wax cappings with moth larvae wriggling. There seemed to be many bees in this hive. I actually made a split from it which is going great guns with a new queen this early summer. In fact the other over wintered colony is good too. I am down to four now. One tbought was CCD? The fact there was no virgin or mated queen with even a small cluster made me wonder…

Alan Montgomery
Reply

Hi Rusty;

Thanks! So, maybe tomorrow morning early when it is cool install boards and remove boards and supers when it is a lot cooler on tuesday morning @ 7am?

Rusty
Reply

Alan,

That sounds good, but check to make sure the supers are fairly empty. Sometimes when I put escape boards under multiple supers, I have to wait ttwo days.

Francis
Reply

I like the recommended robber device but this company’s shipping is outrageous…hopefully that will change in future….I don’t mind paying a fair price but almost $19 to ship 2 is a rip off.

Rusty
Reply

Francis,

Thanks. I didn’t realize the shipping was so high. I think all companies need to take a serious like at pricing. When shipping is more than the product, something is wrong. I often skip orders because of that.

Alan Montgomery
Reply

Anyone got a 100% product that eliminates odor of butyric acid, i.e BeeGone? I had about a pint of it spill in a wooden cabinet and whole garage reeks to high heaven..😕 thanks!

Rusty
Reply

Alan,

Ewww. That sounds bad. Anyone have an idea?

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