I saw tree bumblebee as far north as Montrose last summer, just one. This spring 4 queens! I’m not so keen, it’s natural, not introduced, but I worry about competition with our other species as they seem to be more aggressive setting up nest sites, ousting others, and I had many reported stings from people with nest in their garden/house/shed/bird box/etc, when I was doing my phd. It’s strange seeing a new bee going about here which has never been here before. My friends in Stirling say they’re one of the most common species now, having only appeared there a few years ago.