Question

why flies glow at night?

Answer 1

Flies don't glow fireflies glow

Fireflies produce a chemical reaction inside their bodies that allows them to light up. This type of light production is called bioluminescence. ... When oxygen combines with calcium, adenosine triphosphate (ATP) and the chemical luciferin in the presence of luciferase, a bioluminescent enzyme, light is produced.

Answer 2

Flies don't live long enough for it to be much of a problem. During the night, as do many insects, they cling to the underside of leaves, etc, until dawn and the rising air temperature brings them up to full activity.