The Snelgrove Board Method: Swarm Control Through Timed Entrances
How the Snelgrove board uses a sequence of alternating entrances between brood boxes to suppress swarming impulse while keeping a colony's full foraging force intact.
What a Snelgrove board actually does
Invented by L.E. Snelgrove in the 1930s and refined by generations of beekeepers since, the Snelgrove board is a specialised division board fitted with a set of sliding shutters on all four sides, each shutter covering its own small entrance. Physically it sits between two brood boxes, much like a queen excluder or clearer board would, but instead of simply separating the boxes it lets the beekeeper control exactly which entrance foragers use on any given day. The genius of the method is that flying bees are creatures of habit: they memorise the position of their entrance relative to landmarks and the sun, and they will keep returning to that spot even after the colony inside has been rearranged.
By deliberately splitting the queen away from the flying force and then manipulating which door those foragers use, a beekeeper can concentrate returning bees onto the queenless portion of the split, artificially boosting its strength while robbing the queenright portion of the field bees that would otherwise fuel swarm preparations. It is, in effect, a way of running the colony as two temporarily separated units sharing one stack of boxes, without the labour of physically moving hives around the apiary.
Setting up the split
The classic Snelgrove sequence starts once queen cells are found, or in a routine swarm-prevention regime, once a colony reaches the strength where swarming becomes likely. The queen, on a frame of open brood, is moved to a new box placed on the original floor. Most of the flying bees and several frames of brood remain in the upper box, where all queen cells except one or two are destroyed, or a ripe cell is left to produce a virgin queen. The Snelgrove board is inserted between the two boxes with all four shutters initially set so that the upper entrance faces the same direction as the original hive entrance, while the lower box (with the queen) has its own entrance at the front as normal.
Because foragers orient to the original entrance position, they return to find the upper box's entrance in the familiar spot and pile in there rather than down at the queen's new entrance below. This immediately strips the queenright lower box of much of its flying strength, sharply curbing the impulse to swarm, while the queenless upper box swells with returning foragers who help feed developing brood and any queen cells.
The alternating entrance sequence
Over the following one to two weeks the beekeeper works through a scripted sequence of shutter changes, typically switching the active entrance from one side of the board to another every three to four days. Each switch redirects a fresh wave of returning foragers to whichever box currently needs reinforcing, allowing fine control over population balance between the queenright and queenless halves. A common schedule closes all entrances except one at the outset, then alternates the open entrance to the opposite side after roughly four days, and alternates again a few days later, timed to coincide with queen cell maturation and eventual emergence.
This entrance choreography also serves a second purpose: it disrupts the cues that trigger a virgin queen's mating flight timing relative to colony mood, giving the beekeeper a window to check cell quality, remove surplus cells, or unite the two halves back together once a new queen is confirmed laying, all without ever needing to search for and cage the old queen a second time.
Why beekeepers still choose this method over a simple split
Compared with a conventional artificial swarm, which typically separates queen and flying bees into two hives standing apart in the apiary, the Snelgrove board keeps everything in one vertical stack, which matters a great deal in gardens, allotments, or urban apiaries where space for extra hive stands is limited. It also avoids the awkward business of physically carrying a heavy brood box to a new stand three metres away, and it sidesteps the drifting problems that can occur when two visually identical hives sit side by side.
Because the method works with bee orientation behaviour rather than against it, colonies treated this way tend to stay remarkably calm throughout the process, with none of the roaring and confusion that follows a hive being physically moved. Many experienced UK beekeepers running Snelgrove boards report that a colony can be taken from full swarm preparation with capped queen cells right through requeening and reunification in under three weeks, with a minimal dip in honey yield because the flying force is never allowed to sit idle.
Practical pitfalls to plan for
The method demands a beekeeper who can commit to a precise calendar of visits; missing a scheduled entrance switch by even a few days can undermine the population balance the technique relies on, either starving the queenless portion of foragers or allowing the queenright box to rebuild swarming strength unchecked. Boards must also be built or bought to a good standard, since loose-fitting shutters let bees find unintended gaps and defeat the whole orientation trick.
Weather is another variable: on poor flying days when foragers stay home, the redirection effect is muted simply because there is less traffic to redirect, so the schedule may need small adjustments in a wet spring. Despite these demands, for beekeepers managing several colonies in a fixed apiary who want swarm control without expanding their number of stands, the Snelgrove board remains one of the most elegant tools in the advanced management toolkit.
Frequently Asked Questions
Do I need a purpose-built Snelgrove board, or can I improvise one?
A genuine Snelgrove board has four independent sliding shutters, one per side, each opening onto its own small entrance slot. Commercial suppliers sell them ready-made, and many experienced woodworking beekeepers build their own from plywood, but a simple queen excluder or clearer board will not work since it lacks the directional entrance control the method depends on.
How is this different from a standard artificial swarm?
A standard artificial swarm physically separates queen and flying bees into two hives on different stands. The Snelgrove method keeps both halves stacked in the same location and instead uses the board's shutters to redirect returning foragers between the two, achieving a similar population split without moving any equipment.
Can this method be combined with requeening?
Yes, and this is one of its most common uses. Because the queenless upper box is left with cells to raise a new queen, the sequence naturally produces a mated, laying replacement queen by the time reunification occurs, making it a two-in-one swarm control and requeening technique.
What happens if I get the entrance timing wrong?
Switching too early or too late unbalances the intended population shift: too early and the queenright box never loses enough foragers to relieve swarming pressure, too late and the queenless box can become overcrowded and prone to its own swarm preparations from the virgin queen's colony. Sticking closely to the planned schedule, adjusted only for very poor flying weather, gives the most reliable results.