These guys (and gals) look dangerous and/or gross, but they're not. They also smell a little questionable. However, they like to live in compost piles, especially those with lots of food in them, and that are very damp. The maggots (larvae) are munching away & harmless. The adults look like they might sting, but don't. They're also kind of pathetic fliers & are well loved by spiders. Don't kill these creatures (except to feed them to your chickens, who will thank you).