Metal Queen excluder

01 · WHY 4.14 MM

The figure that separates worker from queen

An excluder is not just any barrier: it is a calibrated sieve. A foraging worker passes a 4.14 mm slot without difficulty; the queen, with a far wider abdomen — and the drone, with his thorax — do not. Set between brood box and supers, the result is that the queen stays below laying and only honey goes up. That is what stops you finding brood among the harvest frames, which complicates extraction, dirties the wax and forces you to set aside frames that were otherwise ready. A wider gap lets the queen up; a narrower one holds the workers back and costs you crop.

02 · THE SIZE AND HOW IT SITS

410 × 510 mm, resting on the rebate

This is the standard 10-frame size, common to Langstroth and Dadant, and it serves on static and migratory hives alike. The excluder does not clip in: it rests on the rebate of the box and stays there, so seeing a few millimetres of offset between the edge of the grid and the outer edge of the timber is normal and opens no gap — what matters is that the grid covers the whole internal opening. On 12-frame boxes this size falls short and you need its own.

03 · FRAMELESS: WHAT YOU GAIN AND PAY

Flatter and cheaper, but propolised onto the top bars

Being a bare grid, it rests directly on the frame top bars: there is no bee space between timber and grid, and the bees propolise it onto the bars. By the second or third inspection it no longer lifts in one pull — ease it off with the hive tool from a corner. A wooden-framed excluder leaves clearance above and below and comes away far more easily; in exchange it costs more, stands taller and stores bulkier. This one wins on price, on being flat, and on the fact that the galvanised finish takes cleaning by blade or flame year after year without warping or rusting. Against plastic: that one weighs less, this one does not bow.

04 · BEFORE YOU BUY

It goes on as the flow starts, when the supers go on, and comes off at harvest or stays according to each beekeeper's method. Before fitting it, check the queen is below: an excluder fitted with the queen in the super achieves exactly the opposite of what you want. And go over the grid each season — a slot deformed by a knock lets through what it should not.