Fly-blows: eggs or young maggots of flesh flies: meat is fly-blown when such eggs or larvae have been deposited on it.
Flying-hairs: very long slender surface hairs set in punctures.
Foetid glands: glandular structures from which a foul smelling liquid may be ejected.
Foliaceous: leaf-like, or resembling a leaf.
Folioles: leaf-like processes from a margin or protuberance.
Follicle: = cocoon, q.v.: a cellular sac or tube, as of a gland or ovary.
Folliculate: enclosed in a case, cocoon or follicle.
Food reservoir: Lepidoptera, a blind sac or diverticulum from the bind part of oesophagus lying in abdomen dorsal to the stomach.
Foot: the tarsus, q.v.; improperly used to = leg; but in the plural form refers to legs rather than tarsi: see feet.
Foot-shield: in caterpillars, the chitinous plate on outer side of abdominal feet.