Award Winning Ulster Observation Hive

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Observation hives allows humans to inspect hundreds or thousands of bees closely without risk of stinging. It accomplishes this by setting glass or plexiglass close to the sides of frames on which hundreds of bees crawl about. Observation hives are used in two different ways: as a traveling hive that can be carried about and shown or as a semi-permanent indoor installation with a bee exit to the outdoors.

This project describes the design and building of an improved Ulster Observation Hive.

Prior Art

There are a lot of resources on observation hives. Here are a few of the best:

Ulster Hive

I really like the design of the Ulster Observation Hive. It is basically a 5-frame nuc body with a top that holds a single frame. That adds up to 6 frames. One of the frames below is a feeder so the bees can go several days in their mobile home. Since the hive holds 5 deep frames, it can function as either a semi-permanent indoor hive or a traveling hive.

This style of observation hive is said to have been designed by the German bee scientist, authority on Varroa mites, and author Bernard Mobus while he was at the North of Scotland College of Agriculture in Aberdeen, Scotland. Mobus won the gold metal for equipment at the Apimondia with this design.

Brushy Mountain is the only source in the US for purchasing an Ulster Observation Hive. I think $145 is a great price for this well-built hive but I wanted to build my own and see if I could improve on the Brushy Mountain design.

Here are a couple of improvements I made to the Brushy Mountain design:

  • The screened bottom board is flush with the bottom of the nuc body. There is no frame to provide a place for hive beetle to hide. I got this idea from the Freeman Beetle Trap design.
  • Box joints make a stronger, more attractive nuc body
  • High quality stainless steel draw latches don’t rust and are lockable
  • Lexan plastic is lighter and stronger than glass. It is cleaned with mineral oil or WD30. They simply slide out.
  • Additional ventilation holes at top of nuc and top of observation frame reduce moisture build-up. I have heard that the Brushy Mountain Ulster hive can fog up with condensation. I do not have that problem. Of course, you can always drill more holes into your Brushy Mountain hive. Note: if you use these hives outdoors, they should have some protection from rain.
  • People like to crowd around an observation hives. Scalloped side bracing (instead of Brushy Mountain’s truncated triangle) results in a design that is both more graceful, lighter, and provides better visibility of the top frame from the side.
  • The biggest improvement is the design of the top that sits on the nuc body. It is simply four pieces of wood with 1/4” deep grooves on each to hold the Lexan windows. Compare this to other designs. When the top is slid into place and latches locked, the top unit is a solid unit. Since this design is made in pine and it uses less wood than other designs, it is much lighter. Since there are no additional wooden pieces around the perimeter, there is more to see of the frame inside.

Building Notes

I like to cook and to perfect cooking techniques but I don’t like to follow recipes. Likewise with woodworking. So you will not get a recipe here for building an Ulster Hive. Below, I have provided you with more information than you would get from any two-dimensional drawing. I’ve given you a three-dimensional model with all dimensions.

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    If you are a woodworker, you should be as proficient with Google SketchUp as you are with a table saw. The program is free. Download it now and import my Ulster Observation Hive model into it. I have uploaded my model to Google 3D Warehouse where you can download it. You can fly through it like a bee if you wish.

  • I built the nuc body with a box joints. It is the strongest joint because it presents the largest surface area to glue. BTW, did you know that a thin glue application is stronger than a thick one? The strength does not come from the glue itself. Some woodworkers do not like box joints for outdoor applications because it exposes end-grain which will ultimately absorb moisture and weaken the wood. They prefer a miter, lock miter, or rabbit joint.
  • After the glue dries on the box joints and on the top, I drill pilot holes and drive in 2-1/2” screws as well. I cover the holes with plastic wood then prime all wood and follow it with 3 coats of marine varnish. You don’t get that in a commercial hive.
  • I bought all the wood at The Home Depot for less than $20. Yeah, I bought the cheap pine but I rifled through every board to get the boards with smooth sections. All my boards had knots but I cut around them. The result is a cheap, lightweight, knot free hive of smooth grain.
  • The SketchUp model does not show three things: the 6 pull latches, the 8 grooves that hold the 2 Lexan sheets, and the bee-proof screen on the bottom.
    • Practice mounting the pull latch on a piece of scrap first. You don’t want any slop but you don’t want it to pull so hard that the wood around the screws fail. You only get one chance to get all 6 latches right.
    • I could not find a pull latch that I would want to use on my hive in the US so I ordered stainless steel latches from Protex Fasteners Ltd. of England ( Their website ordering is a little challenging and shipping expenses are exorbitant – perhaps because it is shipped via square riggers – but if you persevere you will get your order. I am pleased with the result. I ordered three parts:
      • 18-2075, Light duty fastener/Spring latch clip, qty 6, US$5.28 each
      • 01-613, Strike plate/keeper plate , qty 6, US$0.91 each
      • 613/7 SS, Optional Retaining Pin, qty 6, US$0.76 each
    • The dimensions of the grooves depend on the thickness of sheet plastic you use. I used 1/8” thick Lexan sheet. Lexan is stronger than acrylic sheet so plan accordingly. You can cut Lexan on a table saw but it chips badly. Next time I will either use a band saw (smaller teeth) or scratch and snap like glass. The depth of the groove should not be more than 1/4” because that leaves only 1/2” of wood left for structural integrity (assuming 3/4” thick stock).
    • I cut all grooves using a table saw with a fence. Each groove took 2 cuts since the blade is less than 1/8” thick. This means that you need to cut the grooves in the side of the top piece before you cut the scallops (otherwise you will not have a straight edge to run along the fence.
    • Bottom line with respect to the grooves: according to Michael Bush, the Lexan windows need to be centered and separated by 1-3/4” to 1-7/8” in order to respect bee space. Any more or less and you can expect problems.
    • The bee-proof screen should have exactly 8 wires to the inch. This is fine enough to stop bees but large enough to pass Varroa mites and hive beetle or anything else that the bees do not want in their hive. You can get 8-mesh hardware cloth from Brushy Mountain.
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      The screen is held in place by molding I got at The Home Depot It is shown in the illustration. It is held in place with nails. It is not glued – if the mesh is damaged, it must be capable of being replaced.

  • The top sides are glued to the top bottom (body cover) piece and the rabbit joint is reinforced with 3 2-1/2” wood screws. This may appear to be a relatively weak joint (you could use a box joint here) but once the plexiglass and the top slid in, the unit becomes very rigid and strong.
  • The plate that covers the optional bee exit hole (in the event you want it to function as an outdoor hive or indoor hive with a pipe to the outdoors) is not simply a plate. It is glued to the round plug that ended up inside the hole saw used to cut the hole. The plug re-plugs the hole and so respects bee space.
  • You can staple a section of plastic queen excluder to the bottom of the top piece. This will insure that the queen stays in the top, observable frame once you put her there.


I recently got my Journeyman certification at the Young-Harris/UGA Beekeeping Institute. While there, this hive won a first place ribbon in the beekeeping gadgets category.

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Most rewarding, however, is the awe shown recently by 7th graders when I visited their science class with my Ulster hive filled with bees.  Learn more here.

If you have questions, drop me a line. If you build one, send me a picture.  I welcome your comments and suggestions. Please post them to the Observation Hive stub.