Project 365 day 92: purple dead nettle

There is lots of purple dead nettle in the garden - in the uncultivated area up the side of the lawn, waiting to be dug out of the vegetable patch, invading overgrown borders.  The speedwell in bud beside it will soon be adding a blue haze to the patches of purple. The insect was an accidental capture, which I discovered when I downloaded today's photos. This is my excuse for the poor focus, along with the very windy conditions - everything was waving wildly. I think it maybe a bee fly, but I would welcome help with identification.