Flight season: April into September.
Flowers visited: In the valley, these bees seem to prefer bilberry when flowering in the spring, wild raspberry will attract large numbers as will heathers later in the year.
Nesting preferences: Usually the queen will nest in small rodent burrows like the white-tailed bumblebee, Bombus lucorum, and the buff-tailed, B. terrestris, surrounded by a workforce of roughly 200 bees.
Status: Quite local in Wales becoming more common further North into Scotland.
Parasites: The bohemian cuckoo bumblebee, Bombus bohemicus.
Similar species: Very similar to the white tailed bumblebee, Bombus lucorum, and morphological characteristics to distinguish this bee are up for debate. However, the yellow collar extending well below the wing bases and curling beneath them is thought to be a good indicator of this species. In Bombus lucorum this collar rarely extends below the wing bases.
Description: Like white-tailed bumblebees, the Northern white-tail has two bands of lemon-yellow and a pure white tail contrasting strongly with hairs of deepest black. The shoulder collar of yellow extends and curls right underneath the wing bases in the queen bees, separating from Bombus lucorum, but the workers and males are thought to be fairly indistinguishable. The nest built by this bee can be parasitised by the rare Bohemian cuckoo bee, Bombus bohemicus, but I am yet to find this bee in the valley (although I have found it on Wrexham colliery spoil heap so it is definitely around)! Bombus magnus seems to enjoy living in areas well above sea-level and it seems to be the most common yellow/black and white bumblebee on the valley tops.
Where to see them: I have only found this pretty species on the heathland surrounding Y Foel and also foraging on the wild raspberry of Nantyr. However, I would expect that they can be found all over the valley tops if there is suitable heathland. Not one I would expect to see in a garden at the valley’s base.
Northern white-tailed bumblebee
The difference in the yellow collars in the queens of Bombus magnus (L) and Bombus lucorum (R).