As a follow-up to my previous contributions to The ABK, each of which concentrated on one aspect of bee management or hive design, I would like to present an integrated package of small modifications that should lead to big improvements in hive health.
The overall aim is to incorporate features for Small Hive Beetle (SHB) control, mite control (if and when they arrive in Australia), adequate bottom ventilation, and insulated, non-ventilated lids with the same external dimensions as migratory lids.
My article (Re: Screened Bottom Boards, The ABK, December 2014. p.236), outlines reasons for having six-mesh for the entire interior floor of the hive. Briefly, Jerry Freeman in the USA used infra-red photography inside hives to discover that bees chase SHB down the wall and through the mesh, provided there are not any horizontal ledges for the SHB to run around on. Although Freeman traps SHB in oil trays below the mesh, I have discovered that mesh alone is enough to keep hives almost free of SHB without any other form of SHB control. In that article, I erroneously advised that the mesh openings were four mm square. They are 3.33mm square. The arithmetic is six openings and six wires 0.9mm diameter in 25.4mm.
All of the screened bottoms for Varroa management, as illustrated on-line and in Somerville and Collins' work, are of eight-mesh which is not wall-to-wall. Six-mesh would serve just as well as the eight-mesh universally used for Varroa and tracheal mite treatments, and in my experience it does not clog with detritus and need servicing. In view of Freeman's work, there is reason to doubt whether any of the hive bottoms currently made of plastic are as effective as wall-to-wall, flush, six-mesh bottoms for expelling SHB without the use of traps, but there is no reason why such bases could not be modified to meet Freeman's specifications either by an injection-moulded plastic-mesh floor or captive stainless steel six-mesh wall-to-wall. (I have seen kitchen ware with SS mesh captured in plastic, so why not hive bottoms?)
My contribution (Beehive Ventilation, Insulation and the False Paradigm, The ABK, July 2015, p. 8) goes into lengthy detail as to why I agree with overseas researchers that it is a mistake to ventilate hive lids, and why insulation of lids is critical in winter and beneficial in summer. I was surprised to read reports that even in snow country, hives with open bottoms do better than those without adequate bottom ventilation. Even more surprising was the realisation that I alone thought that a skirt below the mesh was needed as a sort of windbreak against cold winter winds.
To briefly recapitulate, the brood cluster is the "engine" that drives stale air and moisture out of hives, provided there is no top opening to induce a chimney effect, which bees are not programmed to handle. In winter and on cold nights, hot moist stale air rising from the brood cluster hits an insulated lid and is forced to the walls by the hot air rising below it. It cools and sinks, and leaves the hive, taking its moisture load and unwanted carbon dioxide with it. A cold, non-insulated lid will cause the moisture to condense and stay in the hive. Bees can tolerate cold dry conditions, but cold wet conditions are problematic. Worst of all, a ventilated non-insulated lid might allow the escape of carbon dioxide, but will allow the retention of water and excessive dissipation of heat. In summer, the same natural circulation removes water from nectar. Evaporative cooling causes moist cool air to sink and flow out the bottom of the hive. See Diagram 1.
A suggested new lid design is shown in Diagram 2, and conversion of a ventilated migratory lid in Diagram 3.
The skirted mesh bottom illustrated on p.237 of the December 2014 ABK article suits my beekeeping operation, as all my hives are on stands 600mm high to avoid cane toads. That design is not suitable for placing on the ground, because ventilation would be restricted to the full-width entrance and a small area at ground level. With a deep skirt of doubtful necessity, requiring a cross-brace, it has no clearance for Emlock fasteners if hives are loaded vertically for transport.
At the QBA field day on 13 June 2015 I explained my package of ideas to David Horton of Burnett Beekeeping Supplies. We bounced ideas off one another and came up with a new hive-bottom design, the ideas for which could fairly be attributed to Tadman, Freeman and Horton. The TFH design is illustrated in Figure 4.
The pieces of hoop pine, treated with copper napthenate are a standard lid rim, below the mesh, and risers above the mesh. The piece forming the landing board was originally intended to be a lifting cleat (treated with copper napthenate). The bottom cleats are of CCA treated exotic pine, 70 X 35 mm, as used for studs in house construction. (Cypress pine is also a popular base-cleat species, for its natural resistance to termites.)
A bead of construction adhesive was used to seal around the edges of the mesh, between the base rim and the risers, and to fill the exposed mesh at the hive entrance.
The wall-to-wall mesh, full-width entrance and the 45mm high opening along the sides should afford adequate bottom ventilation even when the hive is on the ground. The approx. 40 - 50mm rim below the mesh should provide the full-perimeter escape for SHB identified by Freeman, as well as the structural strength needed to support the mesh floor if used as a loose bottom. The base may be screwed to the brood box to ensure proper alignment for SHB escape, and for keeping the hive intact if knocked off its stand by cattle.
Note that the sub-frame for the wall-to-wall six-mesh is the same as a migratory lid rim (with or without ventilation holes), which neatly solves several requirements. It should be sturdy enough to carry the mesh and riser and to withstand compression by the strap of an Emlock fastener, without needing a cross brace. SHB and mites have the full floor area of mesh to maximise their exit from the hive before some of them land on top of the cleats.
If the hive is on the ground, the entrance plus the open area afforded by the cleats should provide adequate bottom ventilation. If hives are stacked in several layers on a truck, the cleats will provide clearance for the racks and spools of Emlock fasteners. The landing board is the same as a lifting cleat but without a radiused or bevelled top, and the bottom cleats are the same as on common solid bottoms, so the supplier can use current standard components in a new system.
The TFH base design does not incorporate either an oil or diatomaceous earth trap, or a tray for a sticky mat to monitor Varroa or other mites. I would argue that only a small percentage of bases in large apiaries need modifications for monitoring purposes; and SHB and mites once sent through a mesh floor do not re-enter the hive, so we do not need the hassle of servicing traps.
So where to from here? Converting migratory lids to sealed, ceiled and insulated is no big deal, but converting solid bottoms to full-mesh bottoms is impracticable, especially for fixed-bottom brood boxes. The quick, half-way fix is to make screened ventilation holes in batches of bottoms, and go on using SHB traps. The long-term plan would be to only use full-mesh bottoms for replacements or additional hives.
In the fifteen years since I resumed beekeeping, I have really appreciated the valuable advice freely given by more experienced beekeepers. This is why I want to share information which could be of great benefit to many. In conversations with beekeepers and suppliers at the recent QBA Conference and field day, I was surprised to learn that several are already using non-vented and sometimes insulated lids, some are using part-mesh bottoms, at least one is using perforated galvanised iron bottoms, but none seem to have hit on the full package outlined above.
All of the hive-component suppliers at the QBA Conference and field day were advised that my article might spark interest in new lid and base designs and conversion kits, so they would not be caught unaware. These design criteria apply equally to traditional wooden hives and to plastic hives, whether injection moulded or glass-reinforced.
A few suppliers were understandably cautious and loath to abandon conventional wisdom, but will possibly convert when they have read the article on lid insulation and bottom ventilation and the benefits of mesh bottoms. One was openly hostile, and the source of the unfounded rumour that mesh floors damage the bees' feet and lead to weak colonies and reduced honey production.
In conclusion I would like to state that I have relied heavily on my own observations and relevant parts of other people's research. My only claim to intellectual property lies in integrating the requirements of ventilation, insulation, water removal, SHB control and mite control into a simplified hive design compatible with existing Australian standard Langstroth hives, suitable for fixed locations or migratory operations.
I will be doing a production run for my own use, and David Horton of Burnett Beekeeping Supplies is looking at doing a trial run of lids and bases for sale. Others are invited to do the same. I doubt the designs are patentable or enforceable, and while I am confident they will live up to expectations, I cannot guarantee that they will.
Author: John Tadman