Find out why before you decide whether
Uniting moves everything the weak colony has into the strong one. Its bees, its comb, its stores, and also its mites, its viruses and anything wrong with its brood. That is fine when the colony is small for an innocent reason and dangerous when it is not.
Innocent reasons include a late swarm, a supersedure that cost the colony a brood cycle, a nuc that simply did not have time, or a queen that started laying late. Colonies like this are small but healthy, and they combine well.
The reasons that should stop you:
- Varroa and the viruses that ride with it. By far the most common cause of a colony collapsing in late summer. Combining it means handing a healthy colony a mite load and a virus load at the worst possible moment. Count first, and treat before you unite rather than after.
- Brood disease. American foulbrood must never be combined into another colony, and in many places it is notifiable and the colony must be destroyed. European foulbrood also needs identifying rather than merging. If brood looks wrong, sunken, greasy, discoloured or smells off, stop and get it identified.
- A cause you cannot name. If you genuinely do not know why a colony has dwindled, that is a reason not to unite it. An unexplained collapse is a diagnosis you have not made yet.
Decide the queen question first
Two queens cannot be united and both survive. If you leave it to the bees, one will die, and it is not reliably the one you would have chosen. So choose deliberately.
The usual approach is to remove the queen you rate less highly a day or so before combining, then unite the now-queenless colony onto the one you are keeping. Judge on laying pattern, temperament and age rather than on which colony is bigger, because the bigger colony is often bigger for reasons that have nothing to do with its queen.
A genuinely queenless colony in autumn is a different case and a simpler one. It has no future on its own, cannot raise a queen that late, and should be united or shaken out.
The newspaper method
Straightforward, and almost universally used because it works:
- Confirm the colony being moved is queenless.
- Take the lid off the colony you are keeping, and lay a single sheet of newspaper across the top bars.
- Cut two or three small slits in it. Small. The point is a slow start, not an opening.
- Set the queenless colony's brood box directly on top of the newspaper, then close up.
- Leave them alone for about a week.
The paper holds the two colonies apart long enough for their scents to mingle, which is what prevents fighting. They chew through it over a day or so, and shredded newsprint outside the entrance is how you know it worked.
After a week, go in and tidy up: consolidate the frames worth keeping, remove empty comb and boxes the colony no longer needs, and get the hive down to the space it can actually hold warm. A combined colony sitting in twice the equipment it needs has swapped one problem for another.
Timing, and why September beats November
Combine early enough that the result still has time to settle, reorganise its stores and take feed if it needs to. Once it is genuinely cold, the useful window has passed, and a late combine gives you a disturbed colony heading into weather it cannot recover from.
The other reason for combining early is that it changes what the rest of your autumn looks like. One colony to feed instead of two, one to assess, one lot of stores to hit a target with. Doing it in September means the feeding guide and the stores target apply to a colony that actually exists rather than one you are hoping will pull through.
Where beekeepers disagree
Two questions here have no settled answer, and anyone who tells you otherwise is describing their own climate.
Two weak colonies, or a weak one into a strong one? Uniting into a strong colony gives the most reliable survivor and costs you a queen and a colony count. Uniting two weak ones preserves the count but can produce something still marginal. Which is right depends on what you are optimising for, and on how weak "weak" actually is.
How small is too small? Frame counts get quoted confidently and they are all local. A cluster that would be comfortable in a mild maritime winter would not survive on the Canadian prairies. Ask people who keep bees within an hour of you, rather than the internet at large.
Sources and further reading
Anything below that names a month is written for a particular climate. Anchor it to your own first frost date.
- University of Guelph Honey Bee Research Centre, Colony Management, whose demonstrations cover uniting and autumn management in a cold climate.
- Dr Meghan Milbrath, Michigan State University Extension, whose research and extension work covers honey bee health, brood disease and overwintering.
- Honey Bee Health Coalition, Tools for Varroa Management (9th edition), for the mite sampling and treatment that should happen before any colony is united.
- Rusty Burlew, Honey Bee Suite: How to combine colonies using newspaper, a careful walkthrough of the method.
- Betterbee: Using Newspaper to Combine Two Colonies, a short practical summary.
If a brood disease is suspected, your national or state bee inspector is the right first call rather than any article, including this one.