IMO- this study does a good job of putting late season swarms into a biological context. Hepburn asserts that swarming in A. m. is "biphasic" and will likely follow the sequence listed below as they occur at separate times of the year. That fits nicely with the small percentage of late season swarms that we see in the NE during ideal conditions brought on by goldenrod and knotweed.  

The propensity for and frequency of swarming varies among colonies on a regional and
often very local level, almost always associated with the sequence rainfall > flowering >
swarming. If the usual season for swarming is preceded by drought and dearth, swarming
may be reduced or even totally inhibited At the opposite end of the spectrum unseasonably
heavy rains may provide the insertion of an atypical “extra” swarming period as noted for
A. m. scutellata and A. m. adansonii in arid regions (cf. Hepburn and Radloff, 1998).
In several other regions reproductive swarming is regularly biphasic and corresponds to
separated major flowering periods. 


Hepburn, H. R. "Absconding, migration and swarming in honeybees: an ecological and evolutionary perspective." Life cycles in social insects–behaviour, ecology and evolution. St. Petersburg University Press, St. Petersburg (2006): 121-136.
APA	

http://entomology.bio.spbu.ru/personal/kipyatkov/pdf/publ/life_cycles-2006.pdf#page=134


Bill Hesbach
Cheshire CT
Northeast USA

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