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Summer Swarms: A prelude to usurpation (colony takeover)

By December 11, 2020No Comments

Beginning in late June, well after our spring nectar flow, comes the time I call usurpation season. I stop the truck well away from my hives and walk slowly into my research apiaries looking down, searching. I keep the area clear around the hives so I can spot any unusual bee behavior –– especially on the ground (see Figure 1).

I carefully search the area around the hives and the hive stands. I look over the outsides of the hives and under them too. Then I look around the bushes and up into the trees. What am I looking for?

The bees on the ground could be swarms clustered in variable sizes, flat like a dinner plate on the dirt. The swarm cluster could be under the hive, tangled in the hive stand. Or a small swarm might have landed under the front end of the hive entrance, appearing cryptically as a small bee beard, belonging to the established colony. In reality –– it is a small independent swarm. Other clusters could be only a small knot of bees, around a queen (here called a queen ball) about the size of a hickory nut.

Off the ground, I search for swarms, variable in size from a handful of bees to a three-pound package in size. This search is not how I look for spring reproductive swarms, where my vision sweeps high up among the tree branches. Those spring swarms on the ground are rare, caused by a queen with damaged wings, or fragments of a soaked cluster hurled from tree limbs, the bees barely surviving a night of violent spring storms.

Back to the summer; on the ground, these small masses of bees are easily missed among hives in thick grass, especially with beekeepers busy with numerous jobs in the apiary. Small swarms off the ground are not very noticeable either. Moreover, these bee behaviors are relatively new occurrences in our apiculture. Beekeepers do not routinely look for them. And to make matters more cryptic, we do not know how widespread these behaviors have become across our country. Before proceeding, we need more background information on bees balling a queen.

We just finished a six-part queen introduction series and observed bees of an established queenless colony balling the cage screen containing a new foreign queen. In that situation (context), without the cage, the bees would form a small ball around the new queen and hold her until she died. For bee management, beekeepers should avoid queen balling to safeguard their queen bees; queen balling is complicated, and far from being completely understood.

Bees can ball a queen, apparently to “hold” her or maybe protect her. When that happens before a usurpation swarm invades an established colony, the queen balling might stall the takeover process. However for now that statement remains an untested hypothesis. Yet I know when the usurpation swarm rushes into the established colony (host colony), the usurpation queen is immediately balled, the ball being found near the entrance. Presumably the bees in the ball are usurpation bees, but that has not been confirmed. Deep in the brood nest a ball of bees quickly forms around the mother queen of the colony. The origin of those bees is also unknown.

Remarkably then, early in the invasion, the bees ball both queens, usurpation and mother. Not only are the origins of bees balling the queens unknown, but their origin could change over time. At this time, limited fighting breaks out between the usurpation swarm and the colony. The dead bees appear in front of the hive. In addition to searching for bee clusters on the ground, one should look for a scattering of dead bees, as a possible recent usurpation event, although it needs verification with a hive inspection. (Foraging ants and small animals can remove the dead bees, so expect this symptom not to persist.)

Most astonishingly, the usurpation queen can become the accepted queen of the colony in as little as 13 hours –– about half a day. The usurpation queen can begin laying her eggs in the brood nest of the mother queen as the mother queen dies in a queen ball. In my bee house where I can house up to 30 single-comb top-bar observation hives, I observed this incredible takeover in one of those glass hives. From that hive and others, I know the usurpation queen becomes balled near the entrance. The ball around the mother queen may slowly descend to the hive floor. Therefore when searching the host hive for queen balls, go all the way down to the bottom board.

On the other hand, usurpation queens do perish in these balls, perhaps if the usurpation queen cannot get through the entrance fast enough, and she becomes encased in a ball of her protecting bees, situated well inside the hive. While questions abound for how the usurpation swarm takes over a colony, the factors for when their process fails are also worthy of study.

Currently, I think a reasonable assumption is that the small summer swarms and queen balls on the ground might be usurpation swarms (or parts of them) that have become stalled or delayed in their attempt to take over an established colony. As a rough working hypothesis, queen balls on the outside of the hive could occur because the usurpation bees protect their queen(s) when their swarm encounters too many foreign bees (as they would upon invading a host colony). One way that could happen is when the usurpation swarms unite, which they readily do.

Swarms uniting are another aspect of summer swarm biology that needs appreciation. Consider first, a beekeeper finds three regular spring reproductive swarms hanging in trees above a row of hives. The immediate concern would be how to catch the swarms before they launch for places unknown. A matter so trivial it never occurs is: What if one swarm launches, hovers, and lands on one of the other swarms, uniting with it? Even more unlikely, what if the remaining smaller swarm flies over and joins with the other two, forming one huge mega-swarm? These summer swarms will routinely unite that way. Although the swarms begin smaller, the resulting swarm may not be all that large, although I am sure there have been exceptions.

I am still trying to observe the sequence of events leading to when these swarms would unite, and the bees, being among foreign bees, begin to ball their queens. I would like to shoot it in slow motion movie clips, for later frame-by-frame study (called scrubbing the film).

One must also concede that some of these summer swarms may behave as absconding swarms or early  ….

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