The insect Danaus plexippus, commonly known as the "Monarch Butterfly", is designated the official State insect of the State of Illinois.
5 ILCS 460/15
State insect
Known as the State Designations Act
The act spans §§ 5-460-1 to 5-460-95 (40 sections).
P.A. 87-273.
Official source: Illinois General Assembly. Reproduced from public-domain Illinois statutes; confirm against the official source for the current text. Not legal advice.