I was out walking my dog this afternoon in a suburan neighborhoodand. I didn’t see a fly anywhere. My dog pooped on the grass and by the time I bent over to pick it up, there were two flies walking around on it. This happens all the time. Where do they come from so quickly? Are they lurking around hiding in the grass just waiting for dogs to come by and do their business?
Well, like most bugs they’re just hanging out waiting for something interesting to happen. For a bug, that pretty much means food or sex. They’ve got plenty of finely tuned sensors to direct them to where the interesting stuff is. Flies are sitting around in bushes and grass and trees, and also just flying around with their sniffers out. The moment they smell something tasty, they’re on it like flies on sh*t.
One of the products of decay is Putrescine one f the others is Cadaverine. I’d imagine that files and other insects, or bugs, looking for a meal are especially suited to detecting and homing in on these scents. They will also lay eggs and start a new generation of flies.