Robbing

Lack of natural nectar sources will very likely trigger robbing. It is not just Honeybees robbing Honeybees but also Wasps and Bumblebees can be seen within the hive trying to rob the stored honey. We are experiencing an extremely dry season for the last few weeks. Without water flowers can't produce nectar. So even if there are flowers around one can't see any bees on them. Bees and Wasps need food to feed their growing population and if there is nothing to be found in the fields they turn to robbing other colonies. Robbing can also be expected in late Autumn when nectar sources become scarce. The only thing a beekeeper can do to minimize robbing is to reduce the entrance size. I have only one 30 mm hole on all my hives which could be sufficient for strong colonies but a bit too big for small colonies. I might start reducing the small colony entrances to just half the hole to reduce robbing. The smaller the entrance the better the bees can guard it. I have not observed full robbing attacks and hope not to see any. 

In this photo one can observe bees trying to evict/kill a Wasp

Here you can can see 3 bees trying to evict/kill a bee which doesn't belong to this hive and
is very likely there to rob some honey. I have observed at least 8 bees being attacked by
 the colony through the observation window