What happens to all of these colonies on the move?
In our area (Puget Sound region), there are sometimes early swarms in April, many more in May through July, and even occasional late-season swarms through August.
The first thing to note is that 75% of them do not survive the year, according to Dr. Thomas Seeley, professor of biology at Cornell University.
If that is the case, why do they swarm?
Honey bee colonies swarm to reproduce the colony, and to reduce the stress of overcrowding. It is a natural phenomenon that has perpetuated honey bee populations for the millions of years of their existence—not just since they’ve been a domestic, managed species.
The old queen departs with up to three quarters of the colony’s workers of all ages, with their crops filled with all the honey they can hold. Left behind are all the eggs, brood, a small worker population, and at least one swarm cell to produce a new queen.
A temporary bivouac is the first stop, usually not too far from the original hive. The travelers cluster around their queen while a few scouts go out to search for a new hive location—which is also usually within a couple of miles. Sometimes the swarm moves again to another bivouac before the scouts guide it to a more permanent site
Once in their new nest site, feral bees can survive. Most do make it through the summer, but according to Dr. Seeley, only 24% of first-year swarm-founded colonies live through the first winter. Nonetheless, if they make it that far, 84% of those surviving colonies will endure up to 5 or 6 years, replacing the queen each summer.
Sometimes a swarm is trapped at the bivouac by bad weather, such as a long wet or cold spell, or a sudden storm. This swarm may simply perish, or it may set up housekeeping right in the open, wherever it had originally landed—in a rosebush, a tree branch, or other relatively unprotected site—and commence building comb without any protective walls around it.
The workers deposit the honey that they carried from the original hive into the new comb, so the daily work of the colony can be resumed. Such an open hive in our area is not destined to make it past summer.
One exception: in August 2019, a small group of us from EJBees “rescued” such a colony and installed it in a regular hive box, where it ultimately did very well….but that’s another story, which you might see on this ejbees.com blog one of these days. …..Susi