Re: Bee hive spacing.
I draw no correlations between proximity of the hives and robbing. When they have the urge/stimulation, they'll rob across the yards as quick as they'll rob the neighbor. In my yards most of the hives are situated on 8' stands and can hold 5 full size langs.
As a dearth kicks in I try to avoid leaving equipment open during inspections, minimize "spilling" nectar, feeding any aromatic syrup, etc. Also judicious use of robber screens as a prophylactic rather than after any robbing has started.
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