(above) Small October cluster on bluebird box. Collected after the flood of 2015 – swarm or abscond?
Last fall we had a large number of interesting events occur here in the South Carolina Midlands as well as regionally. Since Varroa and CCD, autumn colony crashes and declines have greatly increased, however the events of last year appeared to involve colonies suddenly disappearing. Many people were left asking if they swarmed, absconded, flew off to die, or failed to return to the hive.
Late summer and autumn swarming does occur but is an exception and probably occurs only in unique situations. Biology says when the parent hive is ripe for reproduction and all conditions are met the goal is to swarm. Queens that fail to reduce laying during dearth, well fed colonies, with the addition of a brief nectar and pollen flow may indeed swarm during this time of year. Inspect overachieving hives and disrupt the colony by adding empty drawn comb, sharing excess brood with weaker hives, or taking off excess honey stores. This makes the parent hive less than ready and disrupts their plans. Only after all conditions are met will they swarm and if nature or the beekeeper gives them work to do at home they will typically stay. In general, however, this time of year it’s hard for them to feel that conditions are optimal for swarming.
What we saw last year was an apparent increase in abscondings or colony failures where all of the bees left the hive and did not return. Abscondings are typically related to poor conditions in the hive or environment. i.e. starvation, drought, mites, SHB, yellow jackets, critters. Historically these were termed “hunger swarms” but may occur with or without food being present. I like to think of the conditions that precipitate abscondings as stress related. Think of it this way, if your house was overrun with fleas you might stay a while but eventually you’d gather your family up and say, “I’m not sure where we’re going but we’re not staying here.” Same for food; if you lost your income, no job prospects, and had no cash flow for food eventually you’d say, “I don’t know if I can get a job in Timbuktu but I know there are no jobs here so we’re moving.”
How are swarms and abscondings different?
Swarms are generally reproductive in nature and motivated by the organism’s innate drive to reproduce as a result of positive and plentiful stimuli. This is why they usually occur slightly before and at the start of the main nectar flow when resources are at their highest. This gives the swarm the greatest chance of survival. Late season swarms are probably generated by the occasional but less likely situation where the hive is simply full of stores, lacks room for expansion, yet is being stimulated with brief fall pollen and nectar flows. It’s a bad time for them to swarm and in all probability will not have a positive outcome for the issuing swarm.
Abscondings are different in that most of the bees in the hive will leave. It’s like one day they decide they’ve had enough of the poor conditions (stressors) and decide to leave. Unlike a swarm, it is precipitated by negative stressors. The beekeeper comes to the bee yard and finds the hive almost empty. The bees inside are usually bees that were left behind due to being out foraging at the time of the absconding or they are new hatch outs. If there is little capped brood you can assume they have been stressed for some time – scant brood decreases the attractiveness of the bees to the colony.
After last year’s events most beekeepers remarked that they never saw a cluster hanging in a tree nor any new colonies in swarm traps. One possibility is usurpation. Usurpation is when one colony forces its way into another hive and takes over. Apis mellifera scutellata is rather noted for its tendency to usurp calmer races of honey bees. One author promotes the idea that usurpation is more common than we think. The event goes unnoticed as there is no clustered swarm and the landing is not in a tree limb or swarm trap but another hive in the bee yard where they take over operations. Actually, as a survival mechanism, this is quite clever whereby a colony over run with stressors during a time of poor nectar production can unite with another weaker colony and increase its chances of survival.
What about the queen? That may be the $64,000 question. Colony Collapse Disorder symptoms where the queen and a few bees are all that’s left behind continues to mystify many researchers. I’m not going to say I have the answer that the researchers have yet to answer. It is a mystery. But I will say that it’s no mystery that the queen isn’t the only card in the game when it comes to honey bee behavior. Most beekeepers, after a few years in the hives, understand other powers at play within the colony like lack of brood pheromone, population balance, and the host of chemical pheromone balances that signal wellbeing or decline. Leaving without a queen is typically viewed as colony suicide, but as we have already covered above, usurpation might provide an answer to why one colony might leave a failing queen behind.
Another answer proposed to account for the events experienced last year is that the bees died while foraging or failed to return home. While this may be possible, it does not account for the lack of thousands of nurse bees that should have never left the confines of the hive.
In closing, I’m not offering any single cause to what you hopefully will not see this autumn in your bee yard. Last year, here in the Midlands as well as elsewhere, we witnessed multiple accounts of bees absconding. Almost no one saw a cluster hanging in a tree, captured a swarm, or otherwise accounted for the missing bees. We know many of these events were recounted by the beekeeper as having occurred within the course of a week. Forty thousand bees one weekend; two hundred the next weekend. Stressors last year included exceptionally high heat during dearth period, approximately half of normal rainfall, and of course the ever present Varroa mite.
We did an impromptu survey to see if a particular cause could be identified. However, no single cause was identified. In some instances it appeared to be related to mites, in other instances, poor forage or lack of feeding, the much higher than normal temperatures experienced, and/or a rainfall approximately half of typical for our area. Conversely, our survey data showed that those that offered their bees more supportive measures had fewer or no abscondings. Respondents with no abscondings had higher reporting for feeding during the dearth period, treatment for Varroa, availability of water, and overall higher supportive management of their colonies. This would seem to indicate that while no specific stressor could be implicated, a lowering of the stress level by increased supportive management reduced colony abscondings.