We have lots of bees on the liatris and heleniums atm and I’ve been trying to decide which ones they are. These are quite large and I assumed that they are b.terrestris, but we have several males as well that look like leucorum males (will post pic)...so I’m wondering if these are leucorum workers?
I agree with your second pic of the male Bombus lucorum [yellow facial hairs - B.terrestris males have black facial hairs]. As to the first pic - perhaps it is a new B. lucorum queen, with a white tail, there must be some around too if the males are on the wing. It looks quite pristine. I think that workers at the moment look a bit tatty- tired and overworked , nearing the end of their days. Large Bombus terrestris queens would have buff tails. It is very difficult to split Bombus terrestris workers from B.lucorum workers. If you are not sure of i/d, mark any records as Bombus terrestris/lucorum. Can you catch one in a plastic cube, cool it down in your fridge for 10 minutes or so to slow it down, and count the number of antennal segments using a hand lens - male versus female. Release bumble after you have counted. Be quick!