Foot-stalk: of the maxilla, is the stipes.
Foramen: an opening in the body wall for the passage of a vessel or nerve: any opening at an apex: the opening of a cocoon.
Foramen magnum; the opening on the posterior surface of the head to give passage to those structures that extend from head to thorax occipital foramen.
Foramina: small openings in the body wall: in Orthoptera,; the auditory organs on the anterior tibiae.
Forceps: hook or pincer-like processes terminating the abdomen, like specialized appendages of ear-wigs: similar processes in the male, used as clasping organs in copulation.
Forcipate: bearing forceps or similar structures.
Forcipiform: having the form of forceps or pincers.
Fore: anterior.
Foregut: extends from the mouth to the end of gizzard; its epithelium being formed from the ectodermal invagination known as the stomodaeum.
Forehead: in Mallophaga, the head in front of the mandibles and antennae.