54 
Psyche 
[June 
this note is to present evidence indicating that in at least one case, a 
gregarious beetle of the family Lycidae, the clustering behavior of both 
sexes seems to be mediated by a volatile attractant produced by the 
males alone. 
Lycids are widely distributed through the tropics and subtropics, 
commonly are aposematic, are known to be distasteful to many verte- 
brate and invertebrate predators, and frequently figure as dominant 
Mullerian elements in mimetic associations. They form dense aggre- 
gates, sometimes being found by thousands, closely spaced on the 
exposed inflorescences of the host plants on which they feed and mate. 
The particular species on which we worked, Lycus loripes (Chev- 
rolat), is abundant on the grounds of the Southwestern Research 
Station of the American Museum of Natural History, Portal, Ari- 
zona, where this study was made. The locality has been described in 
some detail elsewhere (Linsley et al., 1961), and it will suffice here 
to mention that, at the time of the experiments (July 15-25, 1961), 
the lycids were found almost exclusively on a patch ( ca . 80 x 160 ft.) 
of sweet white clover (Melilotus alba) directly facing the principal 
laboratory building of the Station (Plate 3, fig. 1). Over 3000 L. 
loripes inhabited the patch at the time, distributed more or less irregu- 
larly in dense clusters. These lycids are uniformly yellow-orange in 
color (except for some black on the appendages), and are conspicuous 
on the white flowers of the clover, particularly on those branches 
where they are densely aggregated (Plate 3, fig. 2). They are sluggish 
and do not take readily to flight when disturbed. They fly relatively 
little even on their own initiative, and when they do, it is usually 
during the noon hours. 
Behind the laboratory building there was a second stand of Melt 'lo- 
tus, roughly equal in area to the front patch, but almost entirely devoid 
of lycids. This uninhabited patch became the test arena in which 
formation and growth of aggregations was experimentally induced. 
Initial tests, designed to see whether one could induce lycids to 
aggregate after distributing them singly throughout the test area were 
bound to failure, since these lycids, rather than being attracted to one 
Explanation of Plate 3 
Figure 1. The open field, densely overgrown with Melilotus alba, directly 
in front of the main laboratory building of the Southwestern Research Station, 
Portal, Arizona. On this field was found the main standing aggregation of 
Lycus loripes. 
Figure 2. A cluster of Lycus loripes on an inflorescence-bearing branch of 
Melilotus alba. Within the main lycid aggregation, dozens of branches bore 
one or more such clusters, as well as isolated individuals and mating pairs. 
