40 CFR § 152.5 - Pests.
An organism is declared to be a pest under circumstances that make it deleterious to man or the environment, if it is:
(a) Any vertebrate animal other than man;
(b) Any invertebrate animal, including but not limited to, any insect, other arthropod, nematode, or mollusk such as a slug and snail, but excluding any internal parasite of living man or other living animals;
(c) Any plant growing where not wanted, including any moss, alga, liverwort, or other plant of any higher order, and any plant part such as a root; or
(d) Any fungus, bacterium, virus, prion, or other microorganism, except for those on or in living man or other living animals and those on or in processed food or processed animal feed, beverages, drugs (as defined in FFDCA section 201(g)(1)) and cosmetics (as defined in FFDCA section 201(i)).