It can be very discouraging to know that your best hive has swarmed. Not only will you feel that all your efforts at caring for them over the past year have been thwarted, but you may also feel that you failed to meet the challenge of keeping them in the hive.
A different way of looking at it is this: your careful husbandry of your bees last summer and preparations and care over the winter produced a hive that was born to do exactly what it did. And you can take comfort in the fact that you know how to keep a hive as healthy and strong as it can be. Even if you didn’t succeed in catching the departing swarm, you have sent them out into the world in the best condition possible. Perhaps some lucky beekeeper will find and hive them and marvel at how healthy they are.
It's very tempting to think of your now-diminished hive with less enthusiasm and figure that they should sort themselves out, on their own. But that would be a mistake. As soon as possible, do an inspection to check on the number and age of the queen cells left behind.
Frames with maturing queen cells are quite fragile and should be handled very carefully in order not to damage these irreplaceable developing queens. Even flipping frames up to study the backsides – a common beekeeping maneuver - might, depending on the age of the cells, damage the growing queens’ wing buds.
You may discover a dense jungle of queen cells in all stages of development: ranging from capped cells with thinning tips to still-open cells with fat white queen larvae in them. It's not uncommon to find this range, and biologically it means the departing bees were hedging their bets in case some calamity happens to the first-emerged queens.
If the oldest looking cells still have their tips intact, you may not yet have a new queen afoot in the hive. But if you discover queen cells with holes cut out of their sides, chances are there is at least one queen roaming about and killing her rivals before they can emerge. And you might even have multiple virgin queens already out among the bees. The risk in that case is that the hive can swarm again with a virgin queen, further depleting it. It's possible that a colony will keep swarming with each new crop of virgin queens, until it is too small to be viable.
A typical view of the bottom of a hive body after a swarm, with dozens of queen cells.
Use your hive tool to scrape off surplus queen cells.
For this reason, many savvy beekeepers go back into a hive soon after a swarm and weed out the competition among the queens by destroying cells. This can be risky if you accidentally cull too many cells and then some or all of the remaining ones are damaged. You've got no back-up then.
At the same time, these deliberately-raised queens were all fed the best diet the colony could afford, right from their beginnings. So, these queens can be considered high-quality candidates. One of the best strategies in this situation is to select a few frames with cells and make up one or more nucs with them. Make sure there are enough bees to get these little splits off to a good start. If needed, you can add some frames from another hive to make sure the nuc is strong enough. In this way you are guarding against over-swarming by reducing the number of queen cells in the original hive, while doubling, or even, tripling the chances that at least one high-quality queen will be raised to maturity and return to your yard, well-mated and a worthy replacement for the queen that swarmed.
Queen cell culling is not a pleasant task, but it gives big benefits for the colony, by reducing the chance of after-swarms, also called cast swarms, with virgin queens. As a rule of thumb, leave the parent hive, and any nucs you make up, with just two or three good-looking queen cells (of varying ages) apiece. What’s a good-looking cell? One that’s vertical, well-developed, straight, not conjoined, with no evidence of dings or bumps to the sides.
It’s possible a nearby beekeeper could use a frame with nearly ripe queen cells, but usually you must resign yourself to the work of just culling the remainder. Do it, and move on. Your chickens, if you have any, will relish those tasty pupae.
You don't have a lot of time to accomplish what you've got to do about the queen cells. Remember, queens take scarcely more than a week from capping to emerging, so you can’t afford to dither. Because even if you observed the swarm departing, the earliest queen cells may already have been capped for a couple of days.
Having a good estimate of the queen-cell development timing will also tell you when it is time to check for evidence that the newly-mated queen is back and laying successfully.
That’s important for two reasons: you don’t want to let the hive be without brood for too long, because they may develop a pathological condition called laying worker, which is difficult to resolve.
And if you know when the new queen has resumed laying, you can use the short window when all the old brood has emerged and the new queen’s brood is not yet capped to do a single-dose oxalic acid treatment (either vaporization if you have the equipment and personal protection gear, or a dribble) to reinforce the varroa-suppression effects of the brood break due to the swarming.
Queens emerge from being capped after about a week. They spend another six days hardening their wings and maturing sexually. Add another two or three days to accomplish her mating flights. Egg laying can begin as early as three days after mating. Altogether, this covers a period of 18 or 19 days. Add a day or so more for any weather delays to the mating flights and you get to three weeks as the minimum time from swarming to egg laying. Waiting a full four weeks to check for eggs will mean you are less likely to be disturbing a late-started queen’s mating flights.
It is bittersweet to find a new queen in possession of your old queen's hive, particularly if you didn't catch the departing swarm. But it is the way of the bees, even in managed colonies.