Your hive couldn't defend it due to low population, perhaps lots of bees died off, and or you have entrance reducer not set to a minimum opening.

I just had the same thing happen to a hive i started from a cutout about a month ago. But I was able to capture the queen in a clip, then add two top bars of honey and two bars of capped brood with nurse bees on the combs from another hive. The bees on the combs accepted the caged queen, and all seems to be well. I just saw some bees taking their first flights from that hive today, and the queen bee was running around doing what queen bees do.

TxBeek

I'm surprised they didnâÂÂt kill the queen. Robbing is hard to stop. Once it gets started its hard to stop. Early measures to control it is to put on a robber screen and close off the upper entrance. Most of the time you have a bigger hive in your yard thatâÂÂs causing the problem. Take off the cover on all your hives and smoke them down. This will force them to go home and defend their hive. If you feed honeybee healthy. This stuff will ring the dinner bell. Its better to feed dry sugar if you have to feed.

I'm surprised they didnâÂÂt kill the queen. Robbing is hard to stop. Once it gets started its hard to stop. Early measures to control it is to put on a robber screen and close off the upper entrance. Most of the time you have a bigger hive in your yard thatâÂÂs causing the problem. Take off the cover on all your hives and smoke them down. This will force them to go home and defend their hive. If you feed honeybee healthy. This stuff will ring the dinner bell. Its better to feed dry sugar if you have to feed.