Bumble bee or Cuckoo Bee

Bumble bee or Cuckoo Bee

Observation - Bumble bee or Cuckoo Bee - UK and Ireland. Description: I thought this to be a male B lapidarius but as it was late in the summer and on Knapweed in open grassland on the Dorset cliffs could it B ruderarius?

I thought this to be a male B lapidarius but as it was late in the summer and on Knapweed in open grassland on the Dorset cliffs could it B ruderarius?