460 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1959 
one of the paths through which the hemileucine lifespan appears to 
be limited. The general form of the response is shown diagram- 
matically in figure 2. In intact, free moths it is normally performed 
whenever the insects settle into their stereotyped resting position, 
whatever the nature of the preceding activity. All that is required 
for its release is a contact stimulus to any one of the six tarsi. The 
number of oscillations of the rhythm is readily counted with the naked 
eye, and may be used to give a measure of the strength of the response. 
Moreover, the coordination and release of the rocking pattern are not 
prejudiced by quite drastic surgical procedures involving gross mutila- 
tion of the moth. Thus it is peculiarly susceptible to exact laboratory 
analysis. The full details of this work are to be published elsewhere 
(Blest, in press); although the experimental procedures are made 
somewhat complicated by the presence of interactions between the 
patterns of oviposition and display, in addition to those of flight and 
settling, the picture given by the interaction between the last two re- 
sponses is a simple one. The strength of the rocking response is 
basically determined by two factors alone: (1) The duration of the 
individual’s preceding flight performance (fig. 1); (2) the age 
from the act of eclosion from the pupa, the strength of the response 
diminishing with age. Now, by a happy accident, the species of 
Automeris which happened to be freely available for experimental 
work, Automeris aurantiaca, is one whose display behavior is inter- 
mediate between a typical eyespot display and an aposematic display 
of the Dirphia or Hylesia type, and, to a great extent it shares the 
toughness of these aposematic insects. It is peculiarly resilient to 
experimental interference; moths have been flown and tested for the 
strength of the rocking response after removal of the abdomen, the 
replacement of their blood by Ringer’s solutions containing various 
amounts of added blood sugars, the removal of their antennae and of 
the wind receptors of the head, and the complete section of the indi- 
rect flight muscles and bilateral excision of the wing bases. None 
of these procedures prejudices the relation between flight perform- 
ance and the strength of the rocking response. From this and other 
evidence of a more complex and less direct nature, we can conclude 
that these interactions are controlled by the central nervous system 
without any feedback from the state of metabolic reserves, or from 
the exteroceptive or proprioceptive consequences of flight being in- 
volved; all that is required for the registration of flight performance 
in the central nervous system and its subsequent eapression in terms of 
the rocking response is that the normal pathways for the elicitation 
and maintenance of flight should be stimulated, and that flight itself 
should be performed. In the experiments that have just been inad- 
equately outlined the moths were suspended during flight from artery 
forceps holding a small pinch of the abdominal cuticle; yet the in- 
