I saw my first specimen of a Tree Bumblebee (Bombus hypnorum) today, a queen. This bumblebee was only first seen in the UK in 2000 and has spread quite rapidly but I had not seen it until today. It's actually one of the easiest common bumblebees to distinguish with its 3 clear colour bands - ginger/orange thorax, black abdomen and white tail - so an easy ID even with a quick glance. Exciting stuff (must get out more...)
Also saw the first Brimstone of the year. Lovely signs of spring.