Gavin said "I've personally watched them fly about 9 km to oilseed rape."

I am astounded at 9 km!  That is almost 5.5 miles.  Were you watching
marked bees?  If not, we really have to question the observation.
Studies in the US have found that bees forage very effectively within
a mile, and when desperate will go out 3 miles.  I recall Seeley
questioned whether bees could return to hives with loads of
pollen/nectar/water from much beyond 3 miles.

-- 
Lloyd Spear
Owner Ross Rounds, Inc.
Manufacture of equipment for round comb honey sections,
Sundance Pollen Traps, and producer of Sundance custom labels.
Contact your dealer or www.RossRounds.com

****************************************************
* General Information About BEE-L is available at: *
* http://www.honeybeeworld.com/bee-l/default.htm   *
****************************************************