434 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1926 
Danaus archippus. It is rather curious that this butterfly should 
resemble the milkweed butterfly not only in its color but also in 
its odor. 
The males of our common peacock butterfly (Jwnonia cania, fig. 
25, pl. 3; fig. 43, pl. 9) have a rather strong sweet sugary odor which 
sometimes quickly disappears. The variety examined was the one 
with the under surface of the wings deep dull pinkish red, the com- 
monest in the fields in the vicinity of Washington. 
Mr. Scudder noticed that in the males of the milkweed butterfly 
(Danaus archippus) the scales found in the little pouch upon the 
upper surface of the hind wings next the lower median nervule emit 
a slightly honeyed odor over and above the carroty smell which all 
the scales possess. This odor was detected in nearly all the males 
which I examined. It may be described as like the faint sweet frag- 
rance of red clover blossoms, or of the flowers of the common milk- 
weed. With this is a fainter cockroachlike or carroty odor which is 
found alone, and much stronger, in the females. Mr. Longstaff’s 
notes on the odor of this species which was studied by him in Ja- 
maica, Tobago, Panama, and Venezuela in 1907, and in Australia 
in 1910, and Fritz Miiller’s observations in Brazil, evidently refer 
to the disagreeable odor, and not to the true male odor which escaped 
both observers. 
In the group of which the milkweed butterfly is a member (/w- 
plwine) the evidence seems to show the common or even general oc- 
currence of two quite different scents, a flowerlike scent peculiar to 
the males and a more or less disagreeable mouldy or acid odor com- 
mon to both sexes, often stronger in the females, as in our milkweed 
butterfly. 
Mr. Longstaff says regarding Danaus jamaicensis that of two males 
one had a strong smell of rabbit hutches, the other a decided odor 
as of (?) cockroaches, scarcely disagreeable. Of two females both 
had a strong cockroach smell, perceptible next day. Two males of 
D. eresimus had a “(%) very slight pleasant scent,” and a female 
a “strong (?) muskrat [? Desmana moschata] odor when alive.” 
In the common and widespread Danaus chrysippus (fig. 24, pl. 3) 
of the eastern tropics Doctor Dixey found that the scent in both sexes 
is of a strong and disagreeable nature like that of cockroaches, often 
stronger in the female. In D. genutia (fig. 58, pl. 12) Mr. Longstaff 
sometimes detected an unpleasant scent, but did not record the sex of- 
the individuals examined. Later he found a male to have a slight 
muskrat odor in the field, but none at home, though still alive. 
In Danaus limniace Mr. Longstaff found in a male a very faint 
scent suggesting old cigar boxes; but observations made on other 
occasions were doubtful or negative. Of 11 males of D. septentrio- 
