STUDIES ON PERILLUS BIOCULATUS FAB. OL 
analysis of the blood of the potato beetle grub shows that the reddish 
color is due entirely to carotin and, strangely enough, not a trace of 
xanthophyll could be detected. 
Perillus circumcinctus Stal 
Another species, Perillus circumcinctus Stal, is sometimes found in 
potato fields feeding on Leptinotarsa decemlincata (Say). This species 
of Perillus has been the subject of some confusion as regarding its 
identity and relation to bioculatus Fabricius. 
Van Duzee (1904), in speaking of circumcinctus Stal, says: “I 
have observed but little tendency to vary in this species.” The writer 
is entirely in accord with this statement, and believes that all the varia- 
tion mentioned by Zimmer (1912) was to be found only in specimens 
of bioculatus Fabricius. Distant (1880, Biol. Centr. Am., Heter. I, 
pl. 4, fig. 6) has figured an insect which he took to be a black form 
of cicumcinctus Stal, but judging from the colored figure, the present 
writer is satisfied that it represents an entirely different species. The 
outline of the drawing as well as the coloration is not that of circum- 
cinctus Stal. 
Because of a long acquaintance with bioculatus Fabricius, the 
writer desires to point out some of the differences between this species 
and circumcinctus Stal. In Perillus circumcinctus the pronotum is 
slightly longer and more convex, and this has been pointed out by 
Van Duzee (1904) and Stoner (1920). The coloration of the antennae 
can not be used for distinguishing the species, for in some pale forms 
of bioculatus, segments I, H, and base of III, are brownish to reddish. 
However, certain color aspects of circumcinctus appear to be distinctive, 
and since the species is not variable in this respect, those points are 
mentioned here. The spiracles appear black but are never surrounded 
by a distinct black spot having a diameter greater than the spiracle 
itself. In bioculatus the spiracles are inclosed in a black spot which 
in diameter is at least equal to three times that of the spiracle. In 
circumcinctus the pronotal disk is rarely transversely pale across middle, 
that is, just behind the callosities, but instead there are two broad dark 
brownish rays extending from the callosities to basal margin of disk, 
thus leaving the lateral margins and a distinct longitudinal median ray, 
pale. The dark color on dorsum is always more brown than black, 
also shines with a bronze luster, while the pale areas never become red. 
It is rare to find specimens of bioculatus so dark that the black color 
on base of disk extends to join that covering the calli. There are at 
hand three specimens of bioculatus, selected from perhaps one thousand 
examined, where the black on base of pronotal disk has joined with 
