Psyche 
[September 
198 
The resting attitude as described above was consistently assumed 
by adult males and maintained throughout the day unless the animals 
were disturbed. Adult females almost invariably adopted the de- 
scribed attitude as far as the intermediate limbs were concerned but 
apposed the posterior tibiae to the femora with less consistency. 
Newly hatched nymphs protracted the anterior limbs and folded the 
intermediate ones on assuming their first rest position. The posterior 
limb attitude has not been seen in nymphs up to, and including, the 
fourth instar although it occurs in females of the last (sixth?) 
nymphal instar. To the human observer, from as little as a foot 
away, the insect in the complete resting attitude looks remarkably 
like a stick with four small side shoots and details of the leg structure 
are indistinguishable. 
ACTIVE DEFENSIVE BEHAVIOR 
Escape. 
Many phasmids drop or jump from the substrate in response to 
tactile stimulation (see, for instance, Robinson 1968). This response 
was not induced in P . spinulosus in any circumstances. 
Startle Display. 
The first response to tactile stimulation 1 of adults of either sex 
is the occurrence of wing movements whose function I interpret as 
anti-predator display. Males erected the wings and tegmina ver- 
tically. The wings were maintained in an erect position for upwards 
of one minute when, in the absence of further stimulation, they were 
snapped down. If the stimulus was repeated, or particularly strong, 
the peculiar flexure between the prothorax and mesothorax, shown 
in Figure 2, occurs. This gives the appearance of the insect a bizarre 
effect and may be maintained for some time after the wings are 
lowered. 
Tactile stimulation of the adult female induces a sudden lateral 
extension of the wings beneath the raised tegmina. The main mem- 
branous area of the exposed wings is a translucent dark brown 
traversed by almost black radiate veins. The costal areas and the 
inferior surfaces of the tegmina are a conspicuous carmine. The 
expansion of the wings and erection of the tegmina thus reveals a 
strikingly colored area which is in marked contrast to the rest of 
the insect. In sunlight the wings produce metallic reflections. Once 
*It is difficult to standardize tactile stimulation but the responses described 
here were consistently evoked by pinching any part of the body with the 
fingers or forceps. 
