Every time the Sun shines out come various insects including the bumble bees. This one was out on a rather cool day and I think it was having problems getting its wing muscles up to the temperature needed for flight.
That would have been a bit of a problem as it needs a wing muscle temperature of 30C to fly and the air temperature was around 8C. The best it could do was to crawl along the piece of wood it had landed on.
A Late Season Darter
8 hours ago