There were loads of Hoverflies swarming around and settling on the Hogweed flowers in the hedgerows the other day when it was mild and the sun was trying to shine. They look a lot like bees (Hymenoptera) but they are flies (Diptera) so they do not sting. I think at least some of these hoverflies are Episyrphus balteatus known as Marmalade Hoverflies and many of them migrate to Britain each year from the continent.

Hover-flies and other insects on hogweed flowers