Why are there no flies at night, they are visible only during the day?

Question

Why are there no flies at night, they are visible only during the day?

Answer 1

Different kind of flies at night, buthey are still out there.

Answer 2

they're afraid of the itsy bitsy teeny weeny spiders that climb up the waterspout.

Answer 3

they usually sleep at night...

Answer 4

they are not nocturnal

Answer 5

They are sleeping at night.

Answer 6

the eyes of flies are among the most complex in the insect world. theirs are compound eyes with thousands of individual facets, each with its own optic nerve.  inspite of these, they don't navigate well at night so they park in a tree somewhere and just enjoy the light from my moon.