454 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1959 
frightened of displaying moths that they will in the end wholly avoid 
them, others, perhaps the majority, after habituation reach a state in 
which the rhythmic movements act, as do most prey movements, to 
release attack. Thus the possession of rhythmic display components 
is not an unmixed blessing (Blest, 1957b), and these eyespot displays 
are possibly among the least efficient modes of protective behavior; 
they are, in fact, always lines of defense secondary to cryptic or pro- 
cryptic coloration. These latter modes of coloration, when unaccom- 
panied by secondary defense mechanisms, have their own typical 
protective behavior. 
Moths possessing specialized procryptic behavior closely resemble 
objects found commonly in their environment, such as dead leaves, 
bark, etc., and their behavior is closely adapted to their coloration. 
They exhibit no display of any kind, and are unresponsive even to 
violent stimulation. They will, indeed, withstand interference to the 
point of mutilation without responding. One response to interfer- 
ence is, however, retained: the righting response. Moths placed on 
their backs in an inverted position right themselves by elevating all 
the wings so that their dorsal surfaces touch over the thorax. This is 
an adaptive procedure, for the procryptic patterns of the saturniids 
are confined to the upper surfaces of the wings in all but a few cases. 
Procryptic coloration and behavior necessitate certain correlated 
trends; for example, dispersion in the environment sufficient to 
prevent too frequent prey-predator encounters (de Ruiter, 1955). 
Now the suggestion was earlier made (Blest, 1957b), on the basis 
of a small survey of the behavior of the world Saturniidae, that these 
various modes of display behavior were not evolved independently 
within the group, but were instead evolved as a series in which ad- 
vanced species gained displays of high efficiency by modifying both 
their coloration and behavior from the primitive displays possessed 
by their ancestors. 
The primitive display type was supposedly the simple rhythmic 
display, whose components were suggested to be derived from flight 
movements. The heavy-bodied members of the family are unable to 
fly from rest until they have first raised the working temperature 
of their thoracic muscles to some 35° C. by a period of “shivering.” 
If they are strongly stimulated during the shivering process, they 
will perform more-or-less ineffectual flapping movements of the 
wings. It seemed reasonable to argue that the selection and stabiliza- 
tion of certain components of these flapping movements might have 
given rise to rhythmic displays, the subsequent modification of which 
yielded the remaining display types in this order: First, the eyespot 
patterns from which the rhythmic components are missing; next, as 
alternatives, cryptic coloration and behavior, and the various degrees 
of aposematic display. Finally, in the case of aposematic insects, 
