Fireflies are often found during daylight hours, resting on leaves or tree trunks. They are most active, of course, at night. Not flies, as their name suggests, but beetles. This one is a particularly attractive species and in the next photo, you can see it from a side view which shows it head and very large eyes, and the yellow tip of the abdomen which is where the light comes from (bio-luminescence) that we see flashing at night.