Bombus hypnorum

Bombus hypnorum

Observation - Bombus hypnorum - UK and Ireland. Description: I have a 'Tree Bumble Bee nest in the eaves close to my back door, I have noticed a number of times what seems to be a slightly large bee than the workers attempts to enter the nest, where a worker latches on to back of the 'interloper' any thoughts plea

I have a 'Tree Bumble Bee nest in the eaves close to my back door, I have noticed a number of times what seems to be a slightly large bee than the workers attempts to enter the nest, where a worker latches on to back of the 'interloper' any thoughts please?