David, Nothing to brag about, but I've seen my share of swarms over the past 25 years. From my experience, it not uncommon to find a abundance of freshly laid brood from a departing queen in the days (or daze) just prior to swarming. I have also seen, but less frequently, a lack of young brood in the mother colony of a swarm. When I attended a beekeeping course in France, we were taught that the departing queen will lay a large number of eggs before departing to assure the survival of the remaining colony. Ed