> a dozen or so dead bees in each trap (among the other bodies) with bright yellow pollen in their baskets.  

So, they made it back to the hive, landed, but died even before offloading their pollen loads?
I agree that that's strange.
I'd have sampled a few bees, and done some limited dissection to see if they had even offloaded nectar.

A dozen bees in a day is not a large number, as one must assume that if 1,000+ eggs are laid each day, that around 1,000 bees will reach the end of their natural lifespan on that same day, all things being equal.

But you may want to look more closely at the entrance areas of all your hives in that area.  One of the hallmarks of an imidacloprid kill is a very significant "carpet" of jerking, staggering, and dead bees in front of the entrance, including foragers that have not unloaded pollen or nectar.  In the case of a minor source of forage that only a few bees are visiting being contaminated, you'd have a much smaller percentage of kill, but you WOULD have returning foragers unable to offload, due to the neurological damage.  (How they fly home, I don't comprehend, but somehow they do.  Perhaps flying is not as quickly hampered as walking by the neurotoxin.)

A bee does not die of "old age" without first suffering significant wing wear - what did the wings on these bees look like?  We are told that old bees most often do not return from foraging when dying, so a significant accumulation in a dead bee trap is concerning.

Outside of agriculture, the sale of pesticide concentrates seems the biggest threat to urban and suburban bees.  The buyer does not read the label carefully, and does not dilute, so the nectar produced by the ground-drenched plants kills foragers, brood, house bees, all the bees.  There simply isn't a large bold-print "Dilute Before Applying" on the labels, and its needed.

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html