Then they begin their nightly courtship flight up, up, up to tree limbs and high places. The reason they fly up from the grassy places on the ground, is to be easily seen. The males and females want to attract each other and to do so they must get high on a tree limb. Once they find a lofty perch the bugs continue to blink their soft yellow lights most of the night. Each species of lightning bug has its own blinking pattern.
Some species blink in unison.
By working together in a group, they can be seen much better. When choosing her mate, the female looks up high in the trees to see the pattern of twinkling that attracts her. God did not give them beautiful lights and then make them like earthworms. If they burrowed through underground tunnels, and lit up their light underground, no one would see. God gave lightning bugs lights and wings so they can fly and shine their lights where everyone can see them.