Its a very simple law, Shareallicu, the plant protection act. I quoted some of the relevant parts for you:
https://www.aphis.us...ads/PPAText.pdfFirst up is how they define a plant pest. Their definition covers all non-predatory insects and some that are predators (eating bees is considered indirect harm to plants). Presumably ants that farm aphids (a huge amount) or collect plant matter are also included under this umbrella.
(14) PLANT PEST
.—The term ‘‘plant pest’’ means any living
stage of any of the following that can directly or indirectly
injure, cause damage to, or cause disease in any plant or
plant product:
(A) A protozoan.
( B) A nonhuman animal.
( C) A parasitic plant.
(D) A bacterium.
(E) A fungus.
(F) A virus or viroid.
(G) An infectious agent or other pathogen.
(H) Any article similar to or allied with any of the
articles specified in the preceding subparagraphs.
SEC. 411. REGULATION OF MOVEMENT OF PLANT PESTS.
(a) PROHIBITION OF UNAUTHORIZED MOVEMENT OF PLANT PESTS
.—Except as provided in subsection ©, no person shall import,
enter, export, or move in interstate commerce any plant pest, unless
the importation, entry, exportation, or movement is authorized
under general or specific permit and is in accordance with such
regulations as the Secretary may issue to prevent the introduction
of plant pests into the United States or the dissemination of plant
pests within the United States.
(d) PROHIBITION OF UNAUTHORIZED MAILING OF PLANT PESTS
.—
(1) I
N GENERAL
.—Any letter, parcel, box, or other package
containing any plant pest, whether sealed as letter-rate postal
matter or not, is nonmailable and shall not knowingly be con-
veyed in the mail or delivered from any post office or by
any mail carrier, unless the letter, parcel, box, or other package
is mailed in compliance with such regulations as the Secretary
may issue to prevent the dissemination of plant pests into
the United States or interstate.
c) PROHIBITION ON MOVEMENT OF ITEMS WITHOUT AUTHORIZATION
.—No person shall move from a port of entry or interstate
any imported plant, plant product, biological control organism, plant
pest, noxious weed, article, or means of conveyance unless the
imported plant, plant product, biological control organism, plant
pest, noxious weed, article, or means of conveyance—
(1) is inspected and authorized for entry into or transit
movement through the United States; or
(2) is otherwise released by the Secretary.
SEC. 424. PENALTIES FOR VIOLATION.
(a) CRIMINAL PENALTIES
.—Any person that knowingly violates
this title, or that knowingly forges, counterfeits, or, without
authority from the Secretary, uses, alters, defaces, or destroys any
certificate, permit, or other document provided for in this title
shall be guilty of a misdemeanor, and, upon conviction, shall be
fined in accordance with title 18, United States Code, imprisoned
for a period not exceeding 1 year, or both.
( B) CIVIL PENALTIES
.—
(1) I
N GENERAL
.—Any person that violates this title, or
that forges, counterfeits, or, without authority from the Sec-
retary, uses, alters, defaces, or destroys any certificate, permit,
or other document provided for in this title may, after notice
and opportunity for a hearing on the record, be assessed a
civil penalty by the Secretary that does not exceed the greater
of—
(A) $50,000 in the case of any individual (except that
the civil penalty may not exceed $1,000 in the case of
an initial violation of this title by an individual moving
regulated articles not for monetary gain), $250,000 in the
case of any other person for each violation, and $500,000
for all violations adjudicated in a single proceeding; or
( B) twice the gross gain or gross loss for any violation,
forgery, counterfeiting, unauthorized use, defacing, or
destruction of a certificate, permit, or other document pro-
vided for in this title that results in the person deriving
pecuniary gain or causing pecuniary loss to another.