F is for flagging. Flagging is the term for when leaves of a tree die as a result of oviposition (when the cicada lays eggs in the branches of trees).
Photo credit: Daniel Herms, The Ohio State University, Bugwood.org (Forestry Images).
The Floury Baker, aka Aleeta curvicosta, is an Australian cicada. It has excellent camouflage, as you can see from the photo:
Photo credit: Michelle Thompson.
Fidicina is a Genus of cicadae. Here is a photo of a Fidicina mannifera from Brazil.
Formotosena is a Genus of cicadae. Here is a photo of a Formotosena montivaga from Thailand.