Greetings from Nauvoo! I didn't really know what mayflies were until I got out here! They are small, lacy little moth-like flies that only live a few days. They fly around like swarms of gnats do.
One line in Rendezvous says that a boy tied a mayfly to a thread and pinned it in Adelia's hair! Yuk! The second picture shows how thick they are right now. All the white you can see are blurry mayflies in motion!