Why do lightening bugs light up most often at dusk, and less often later at night?

Question

Heck! Why do they light up at all? Why did "evolution" or "God" decide that they need to light up?

Answer 1

The lights are mating signals to the females, which
are commonly wingless and living on the ground.
Each species has a different signal in the male;
the female replies with a flash from the ground, and the male approaches her and mates.

Presumably the reason for their not continuing to
flash all night has several causes. These may
include that all the available females have already
mated after the first couple of hours so the males
are not receiving any answers and stop flashing.
Or there may be a certain length of time they will
flash regardless of conditions. Or they may have to stop to eat some time. I don't know whether
anyone has really tried to provide an answer to
this question.

Besides the true lightning bugs (family Lampyridae) there are other insects that produce
similar lights. These are largely beetles, including
phengodids, and some click beetles (Elateridae),
plus some other orders.

Answer 2

They attract a mate early,cause they want to go bed with her all night, and turn the lights out early.

Answer 3

Cause that's when they get there freak on. Then they are tired and go to sleep.