It rained fairly hard in parts of yesterday and today. You can smell the earthworms–the boy-girl earthworms crawl out of their underground homes to meet up with other boy-girls (or is it girl-boys?)
At the forsythia bush, during a light sprinkle, a number of flies of several different species have congregated. Some have their minds on things that other critters think of during the spring.
But it can be a dangerous party to attend. This fly is probably one of the Scathophagidae–predatory flies whose larva live on dung.