16 
lack data, but it is possible that they are Illinois speci- 
mens. 
The usual explanation for the range restriction of 
oleracea is the harmful competition imposed upon it 
by P. rapae. This has without doubt played an impor- 
tant role in its decline. However, as pointed out by 
Hovanitz (loc. cit.), the reduction of forest cover has 
probably been of equal if not greater importance in 
this respect, by virtually eliminating favorable habitats 
from the portion of the state formerly occupied by the 
species. Whatever the cause, there seems little ques- 
tion that oleracea has been extirpated from the Illinois 
fauna, although there is a possibility that it might oc- 
cur casually in the extreme northeastern part of the 
state. 
Pieris rapae (Linnaeus) 
European cabbage butterfly 
Papilio rapae Linnaeus 1758:468 (type-locality restrict- 
ed to “Sweden” by Verity & Querci 1923:20). 
Pieris rapae: Worthington 1880:47; Holland 1931:282; 
Klots 1951:200; dos Passos 1964:40 (No. 280). 
Illinois records—Map 38. 
This butterfly is abundant throughout Illinois, par- 
ticularly in cultivated areas. Early spring individuals 
are smaller than those in later broods and have less 
heavy dark markings; these are sometimes reduced to 
a mere apical black spot, but we have never seen a 
specimen from Illinois in which the dark markings 
were entirely absent. 
P. rapae is an introduced European species, as its 
common name implies, and is known to everyone as 
an exceedingly destructive pest on cabbage and other 
crucifers. It is foremost among all butterflies in eco- 
nomic importance. It is believed to have reached Ili- 
nois about 1876, and the first definite record of its 
capture appears to have been at “Maplewood, west 
of Chicago” in September, 1877, by Worthington 
(French 1878; ‘Thomas 1880), although Scudder 
(1889) reported unauthenticated records of the insect 
‘a Illinois as early as 1874. Within a few years it 
had occupied the entire state, to the detriment not 
only of its hosts but of the native species of Pieris: proto- 
dice and napi oleracea. 
The earliest and latest dates for rapae in Illinois 
are March 27 and October 6. 
Colias eurytheme Boisduval 
Alfalfa butterfly, orange sulphur 
Golias eurytheme Boisduval 1852: 286 
“California’); Worthington 18802275 
1931:297; Klots 1951:183; dos Passos 1964:41 
286). 
Illinois records.—Map 39. 
Abundant throughout Illinois, eurytheme is proba- 
bly our commonest butterfly. Despite a great deal of 
study in recent years, the relationship between this 
species and philodice is unclear. We have assigned all 
specimens having any orange to eurytheme, and all clear 
yellow specimens to philodice; Klots (1951) indicated 
the reliability of this procedure with respect to eastern- 
area material. As he pointed out, however, white fe- 
males of the two species are not always distinguishable 
(type-locality 
Holland 
(No. 
from each other with certainty; the spots in the borde 
of the fore wing are usually somewhat larger in eury 
theme. 
Individual variants are frequently encountered, near 
ly all of them females. One consistently occurrin 
variation has the upper surface of the fore wings whit 
sometimes with a buff suffusion, whereas the hind wins 
are a light yellow or greenish yellow. White femal 
occasionally have this buff suffusion on both wings witl 
out any yellow or orange. The dark borders of th 
fore wings are occasionally very wide, accompanied | 
an enlargement of the basal dark area, so that the lig! 
area of the fore wings is much restricted. Such a whi 
female was taken at Streator, La Salle County, Septer 
ber 26, 1946, Irwin (INHS). In this individual tl 
hind wings are dark greenish yellow. A female tak 
at Highland Park, Lake County, in August, 1961, | 
May (FMNH) has the primaries and secondaries « 
the left side yellow with those on the right side whi 
Wyatt recorded a similar specimen taken by Bristol 
Elgin, Kane County (AKW). A number of melat 
aberrations of varying degree and of both sexes ha 
been taken in Illinois (FMNH). 
The earliest date of capture of eurytheme in lin 
is March 27. The latest date is December 7, at Arlir 
ton Heights, Cook County, McElhose (FMNH). T 
*5 the latest recorded date of flight for any butterfly 
Illinois. On the day previous to this date, Irwin | 
served the species on the wing at Streator, La S: 
County. 
Colias philodice Godart 
Common or clouded sulphur 
Colias philodice Godart 1819:100 (type-locality “Nc 
America, particularly in Virginia’) ; Worthing 
1880:47; Holland 1931:293; Klots 1951:185; 
Passos 1964:41 (No. 287). 
Illinois records—Map 40. 
The clouded sulphur is common and generally 
tributed throughout Illinois, although it is less ak 
dant than eurytheme. Like that species, philodice t 
to produce frequent individual variants, especially 
the female sex. Some have white fore wings and 
low or yellowish hind wings, analogous to the varia 
in eurytheme. Others may have the light spots in 
fore-wing border nearly or wholly obsolete; these ! 
been found in both the white and yellow phases of 
female. Still others are more or less unique in ma 
of variation. An example is a female taken at Stre 
La Salle County, September 18, 1960, Irwin (IN] 
In this individual the black of the borders is proje 
inwardly along the veins, especially those of the 
wings, giving it an odd appearance somewhat re 
bling Colias cesonia. It was regarded by F.M. B 
as a possible hybrid with cesonia but more like 
mere mutant philodice. Another unusual female 
taken at Streator, La Salle County, 1942, Pl 
(INHS). The dark borders of its hind wing 4 
wide and heavy as those of the fore wings, but wi 
white spots or the. incursion of white ground color 
ing it a superficial appearance suggesting Colias 7 
Edwards. We list these variants to illustrate the ty 
divergence which may be anticipated in the Sf 
Records are from April 10 through November 18. 
eurytheme and philodice are multivoltine; the au 
