A good way of determining the species of a bee is to look at the colour patterns. This one has a white tail which fades into bright yellow, then all it is black up to the ginger collar (with a very slight ginger band in the middle, which may make this a male). This pattern suggests it is a Southern Cuckoo Bee, also known as a Vestal Cuckoo Bee. Another way of recognising cuckoo bees is that they tend to have much darker wings that normal bumblebees. Cuckoo bees are bit bit like the cuckoo bird in that they take over a normal bee's nest. This one parasitises the Buff-tailed Bumblebee.