422 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1926 
more exact, and if their previous experience with odors has been 
adequate their comparisons are likely to be closer. 
The information on our native butterflies in the following pages 
was brought together with the assistance of my two young sons, 
Austin B. J. Clark and Hugh U. Clark, whose assistance in experi- 
menting with some scores of captured butterflies was of the greatest 
value. On our various excursions in the field it fell to them first 
to investigate the butterflies we caught. In most cases I could my- 
self confirm their observations, but in some I was quite unable to 
perceive an odor which both of them assured me was quite strong. 
Ordinarily the testing of the butterflies for odors is an interesting 
and a pleasant task, but one must always be prepared for surprises 
sometimes most unwelcome as in the case of the females of the fritil- 
laries. 
SOURCES OF THE MALE FRAGRANCE 
The flowerlike odors of male butterflies usually have their origin 
in hairs or scales of a peculiar type called androconia found only in 
the males, grouped in special “ brands” or patches in various loca- 
tions on the wings, distributed along the veins, or scattered widely 
on their upper surface. In the males of a species of Melete from 
Brazil, Fritz Miiller found that a rather strong odor was emitted by 
a pencil of nonretractile hairs protruding from the ventral side of 
the abdomen. In the skippers the scent-emitting hairs are sometimes 
placed upon the tibix of the hindmost legs. 
In our common milkweed butterfly (Danaus archippus) the males 
possess, besides the scent scales in the little sack on the hind wings, 
an extensible brush of hairs on either side of the last segment of 
the body which when fully extended radiate in all directions. In 
various related species these hairs are borne upon the inner end of 
a more or less long tube extending into the body within which the 
hairs form a compact tuft ensheathed by the tube walls. This tube 
can be everted or pushed outward in such a way that the inner 
end now becomes the tip of a more or less elongate fingerlike process 
bearing a tuft of radiating hairs. 
Similar organs are found in the Hupleas (fig. 44, pl. 9; fig. 55, 
pl. 12) of the Old World regarding some species of which de Nicé- 
ville says: “The males may often be observed patrolling a small 
aerial space, with the end of the abdomen curled under the body 
toward the thorax, and with the two beautiful yellow anal tufts of 
long hair distended to their fullest extent at right angles to the 
body.” The males of the related 7twnas and Lycoreas, and the 
gorgeous males of Morphos and of their more somber eastern repre- 
sentatives, all have similar extensible appendages. In some forms 
it has been determined that a strong odor is given off by these. 
