I thought robbing is caused by weak hives, large entrances, or opening hives. I've tested open feeding next to hives. It works with Italians. If you open feed my way, there's a danger time when you can't open hives. I don't know when it ends. I equalized 1 week after feeding ended.
Suppose you have hives with 100 kg of nectar sugar, and you feed 100 kg fast. How do feeding methods affect bear interest?
Robbing will be done by any bee that senses an opportune stored feed location with little or no defense. Such as a bucket of sugar set out.
Any hive can be robbed if there are enough other hives out there looking for food, they just pick on the weakest of the bunch, If you have 12 strong hives and 1 average hives, and the 12 strong hives sense that the average hive is the easiest way to get food they will rob it.
But robbing can spread, if you open feed and the feed runs out or the bees internal GPS is off a little and they start going after the hive nearest.
I've seen one weak hive getting robbed, once it was cleaned out the bees kept coming back anyhow, and attempting to rob the next hive in the row.
Yes entrance size relative to the hive strength can normally deter this.
But open feeding right next to your actual hives may cause a feeding frenzy that may envelope the nearest hive as a target.