Annotated checklist of the butterfles of Illinois
By: Roderick R. Irwin, John C. Downey.
Contributors: Downey, John C. 1926-; Illinois. Natural History Survey Division
Series: Biological notes -- no. 81
Publisher: State of Illinois, Dept. of Registration and Education, Natural History Survey Division
Published: 1973
Place of publication: Urbana
Language: eng
Number of pages: 60
Subjects: Butterflies -- Illinois
Notes: Cover title.

"May 1973."

Includes bibliographical references (p. 36-40).