Odd coloured bees

[Allen Brookes]

Hi,

2nd year bee keeping and just needed to know if I’m being too over cautious, as you can see on the picture some of the bees, have a greyish colour below there heads, is this normal?
Thanks

 

[Anduril]

Himalayan Balsam

 

[jenkinsbrynmair]

It's the himalayan balsam mark - you will often see them absolutely covered in white HB pollen (ghost bees) the bees in the photograph have cleaned most of the pollen off and put it in their pollen baskets, but the same as you can't reach to scratch that spot on your back between your shoulder blades
Neither can the bees