4 
in the same county may be represented by a single dot 
on a map. 
All butterflies ever actually taken in Illinois have been 
listed, including such obvious casuals as Timochares 
ruptifasciatus, Eumaeus atala, Nymphalis californica, 
Danaus gilippus strigosus, and Phyciodes texana. We 
decided against segregating such forms, since they repre- 
sent valid records. It is obvious that they are not perma- 
nent components of the state fauna, but attempting to 
segregate them would inevitably have resulted in errors 
of judgment. 
The arrangement and nomenclature of the list for 
the most part follow the latest checklist of the Nearctic 
butterflies (dos Passos, 1964) and its revisions (dos Pas- 
sos, 1969a, 1970). Departures are explained in the dis- 
cussion of the species in question. The species numbers 
are included in the references to the checklist, for exam- 
ple, “dos Passos 1964:3 (No, 24).¢ 
In addition to distributional data, we have presented, 
in condensed form, some information on ecological 
preferences, number of broods per season, and dates of 
earliest and latest capture in Illinois. 
DESCRIPTION OF AREA 
Early in the 19th century, when settlement of Illi- 
nois began, much of the state was forest-covered, but 
also prominent were vast areas of tall-grass prairie with 
woodlands along the larger streams. Vestal (1931) di- 
vided Illinois into eight vegetational divisions on the 
basis of the original flora. Jones & Fuller (1955) as- 
sembled distributional data and maps of Illinois plants 
‘nto a volume which, with the supplement by Winter- 
ringer & Evers (1960), is indispensable to the student of 
Illinois butterflies. 
Nearly all of Illinois lies within the Upper Austral 
life zone, but the southern tip of the state is ecologically 
quite distinct. This consists of the floodplains of the 
Ohio and Mississippi rivers in Alexander, Pulaski, and 
Massac counties. Cypress swamps, formerly extensive, 
are characteristic of this area, which is the most north- 
erly outlier of the Austroriparian subdivision of the Lower 
Austral zone. Its butterfly fauna has corresponding af- 
finities. 
HISTORICAL RESUME 
The earliest recorded butterfly observation and col- 
lecting in Illinois was done by Edward Doubleday, an 
eminent English entomologist, who visited the state in 
the late autumn of 1837. His account of the trip (Double- 
day 1838) contains little entomological observation. The 
insects which Doubleday collected during his journey 
are now in the British Museum. 
The earliest resident worker to make significant con- 
tributions to the knowledge of the Illinois butterfly fauna 
was Benjamin Dann Walsh. The first official State En- 
tomologist of Illinois, he began his studies in 1860 and 
continued them until his death. He was a correspondent 
of W. H. Edwards, and supplied the latter with much 
Illinois material, from which Edwards described at least 
two butterflies. These descriptions are among the earli- 
est specific references to Illinois butterflies. The main 
portion of Walsh’s collection, following his death, was 
deposited in the Chicago Academy of. Sciences, where 
it was destroyed in the Chicago fire of 1871. Some of it, 
however, had been retained by his successor, William 
Le Baron, and became the nucleus of the present col. 
lection of the Illinois Natural History Survey. 
Le Baron and Cyrus Thomas, the second and thirc 
State Entomologists of Illinois, published notes and in 
cidental references to butterflies in their official reports 
chiefly from an economic point of view. 
Scudder (1869) reported 19 species from Mario 
Township, Ogle County. 
French (1878) discussed 61 Illinois butterflies fron 
the economic standpoint, and in 1879 published the ear 
liest comprehensive state list. It is virtually unknow 
and exceedingly rare. The copy recently found in th 
archives of Southern Illinois University is the only on 
known to us and probably one of very few extant. Th 
list is in the form of a rather primitive key to the Ill 
nois species, of which 113 are included. Ninety-nine ¢ 
these are considered to have been correctly attribute 
to Illinois. 
Worthington (1880) published a state list of 12 
species, of which 109 appear to have been validly it 
cluded. Snyder (1896) listed 56 species taken at Nor! 
Evanston, Cook County, and Hart (1903) listed 50) 
the commoner Illinois species. Adams (1915) listed 
small number of butterflies in connection with an ec 
logical study in Coles County. C. L. Remington (194 
published an account of the Rhopalocera of Princip 
College, at Elsah, Jersey County. Wright (1951) list 
and figured 11 of the most common Illinois butt 
flies in a popular manual. Downey (1966) discuss 
the distribution of Lycaenidae in TIilinois. Cushi 
(1970) listed 56 species from the vicinity of Prairietow 
Madison County (one species was incorrectly includec 
Irwin (1971) gave several new records of Hesperiid 
from Illinois, most of which represented important ( 
tensions of known ranges. 
The remaining papers on the Illinois butterfly fau 
(Riley 1870, Wyatt 1905, Frison 1919, C. L. Remi 
ton 1942, Conway 1956, Phillips 1961 and 1966, a 
Irwin 1968) have been limited in scope to one or f 
species. 
Between 1965 and 1969, Irwin prepared various F 
liminary lists of Illinois butterflies, reproduced by hec 
graph and Xerox, which were distributed to the vari 
collaborators in this project as a guide to the prog 
being made. These were cited by Masters (1969). Sc 
of the data they contain have subsequently been revis 
A number of recent Illinois records are contai: 
in the various Field Season Summaries published by 
Lepidopterists’ Society (C. L. Remington 1947; P. 
Remington 1948, 1949, 1951; and Heitzman 1968). 
A more comprehensive account of the history of t 
terfly collecting in Illinois and of the principal collec 
and collections in the state will be published elsew! 
as an outgrowth of this study. | 
SOURCES AND ACKNOWLEDGMENTS 
The principal institutions featuring collections of 
butterflies of Illinois are the Field Museum of Nat 
History in Chicago and the Illinois Natural His 
Survey in Urbana. Smaller collections are founc¢ 
other museums and in various state universities. 
Individual collections at the Field Museum are t! 
