They are becoming a much more common sight in southern England these days due to the warm summers and milder winters.
I first saw one of these delightful little moths over 20 years ago and since then, there has always been a steady flow of the visitors to my garden.
They seem more common around August time and adore plants with "tubular" flowers. Petunias, verbena and abelia are favourites.
They are native to central europe but the caterpillas/pupae are over wintering more and more in the UK due to mild conditions.
They are much smaller than most proper hummingbirds and can be distinguished by the black and white striped abdomen.
I'll see if i can find a pic on google