Fore-intestine: =foregut, q.v.
Forficate: = forcipate, q.v.
Forks: Trichoptera; forks of veins in apical part of wing, numbered 1, 2, 3, etc.
Form: applied to representatives of a species which differ from the normal or type, in some uniform character; it is seasonal if it occurs at a period different from the type; dimorphic if there is an alternation of generations or two color patterns occur; or sexual if the members of one sex differ uniformly from those of the other.
Formic: of, pertaining to or derived from ants.
Formicary: an ant's nest or ant-hill.
Fornicate: arched or vaulted: concave within, convex without.
Fossa -ae: = fossula; q.v.
Fossoria: burrowers: in Orthoptera, the mole crickets and allies; in Hymenoptera, the digging wasps.
Fossorial: formed for or with the habit of digging or burrowing.