What is the importance of the flying glitterbugs in the novel, Hunter’s Moon?

The flying glitterbugs create shimmering swarms of light that the ouranids call "Shining Time," and the coming of Shining Time signals to the ouranids that it is time for some of them to fly across the ocean to icy wastelands where they will die and, according to their new religious faith, merge into a paradisiacal afterlife.