another take on swarming as adaptive behavior in the face of mites...
from the article "epidemiology of honey bee parasites" in parasitology
today, vol.6,no.11,1990 by l.a.royce and p.a.rossignol:

"...it appers that a parasite of social insects has in essence to adapt
to two hosts:
first, the individual worker within a colony, the numbers of which grow
linearly and
second, to the colony itself, the actual reproductive
"organism"...transmission also
has vertical and horizontal components...analysis of tracheal mite
populations in
particular suggests that intracolony parasite levels are regulated by the
swarming
behavior of their hosts...ironically, current and highly productive
methods of honey
bee management with movable hives curb swarming and may contribute to
increasing the spread and the impact of some parasites...this insight may
result in changing management practices to reduce the detrimental effects
of bee parasites."