Leoncini et al. (2004) showed that the number of
foragers in a colony is regulated by a pheromone, ethyl
oleate, produced by existing foragers and spread to preforagers
via trophallaxis. If there are sufficient foragers in a
colony, the production of ethyl oleate is high, and the
transition to foraging in younger workers is delayed. If
there are insufficient foragers the production of ethyl oleate
in the colony is reduced, and this increases the rate at which
younger workers make the transition to foraging.

"If the older ones don't keep them in check, the young ones can mature
too quickly," Huang said. "It's kind of the same thing as with people,
you need the elders to check on the young, even if the young are
physically able to go out on their own, it's not the best situation
for anybody and now we know how it works."

Huang said the system makes sense for the health of the hive. Young
bees – those in the first two to three weeks of life – are
biologically better suited for brood care, thanks to some boosted
blood protein. Bees forced out too early aren't great navigators, and
since foraging is dangerous, they risk dying before their time.

-- 
Peter L Borst
Danby, NY USA
42.35, -76.50
http://picasaweb.google.com/peterlborst

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