BIOLOGY OF SATURNIID MOTHS—BLEST 455 
certain species in the genera Hudyaria and Cerodirphia appear to 
have acquired so great a level of distastefulness linked with general- 
ized aposematic coloration that display has become unnecessary, and 
is no longer maintained by selection. Although individuals of these 
species show themselves capable of performing normal displays, in 
most they are either transient or absent; yet the existence of “per- 
fect” displays in this small minority of individuals leaves no doubt 
that this elimination of the aposematic display pattern has been a 
secondary change. 
A major aim, then, of the work on Barro Colorado was the exam- 
ination of this evolutionary succession in a more narrowly defined 
range of species, by which it was hoped that the intermediate stages 
between the display types would be revealed. This rather optimistic 
expectation was, surprisingly, fulfilled; 21 species of hemileucines 
were found on Barro Colorado. Twelve more species were observed 
during a 6-week period spent in the Arima Valley of Trinidad, fol- 
lowing a generous invitation from the New York Zoological Society 
to work for a period at their Trinidad Field Station. With the addi- 
tion of 10 species seen as the result of purchasing live pupae from 
Argentina, Mexico, and Brazil, the total is now 43 species within 
this subfamily alone. This series is a particularly valuable one, since 
the Hemileucinae exhibit most of the major types of protective col- 
oration found in the Saturniidae, and the interrelationships between 
them can be readily worked out. There is no space in this article 
to present the detailed arguments through which the evolutionary 
succession has been deduced, but the changes which are believed to 
have occurred are as follows: 
The primitive display type within the Hemileucinae is, in fact, a 
rhythmic display, linked with hindwing eyespot patterns, in which 
the forewings are protracted following tactile disturbance to expose 
the eyespots, and the moth executes little hops by means of depression 
flicks of the wings. This type of behavior is found in a large number 
of species of the genus Automeris (13 out of the 20 species so far 
seen). The flicking movements are regularly spaced in time, at inter- 
vals of between 0.5 and 1 second, and the complete flick movement 
itself is completed within little more than one-tenth of a second. 
Analyzed with the ciné camera each flick is found to be a complete 
flight stroke appearing in isolation, and if the moths are very strongly 
stimulated, intermediates between true flapping flight and the ritual- 
ized display flicks can often be obtained. In some species of Auto- 
meris (e.g., A. janus), the flick movements are accompanied by quite 
perceptible “shivering” movements of the wings; the warming-up 
movements preparatory to flight have not been wholly eliminated 
from the displays. Since it is known that shivering movements by 
