Psyche 
[September 
162 
Description of Defensive Behavior 
1. A cauloplacella immunis Brunner (Fam: Pseudophyllinae) 
Specimens of this insect collected at Wau were a more-or-less 
uniform bright green in color. At night when actively moving about 
vegetation the insect looked like a ‘typical’ unspecialized tettigoniid. 
However by day the insect assumed a resting attitude on leaves (both 
upper and lower surfaces) that is shown in Figure 1. 
This posture involves fairly complex changes in the orientation of 
the tegmina, the alignment of the legs and also in the relationship of 
the head, thorax and abdomen to the substrate. The change in the 
orientation of the tegmina is the most striking. Note, from Figure 1., 
that the tegmina are kept together at their posterior margins (which 
lie approximately in the midline of the body) and that their anterior 
margins (which lie lateral to the insect) are closely applied to the 
substrate. In the attitude of the active insect the angle between the 
contiguous tegmina is less than 90° (i.e. between their internal 
surfaces) while it becomes very obtuse (closer to 180°) in the flat- 
tened cryptic posture. In the cryptic posture the tegmina form a 
carapace-like structure that covers the second and third leg pairs. 
This change in the orientation of the tegmina is achieved by slow 
transition. In effect as the insect moves from a locomotory stance 
into its resting posture it lowers the body against the substrate, re- 
orients the limbs, tucks the ventral part of the head beneath the 
prothorax and ‘feathers’ the tegmina outwards. In the resting pos- 
ture the insect has a very low profile and the anterior legs are pro- 
tracted side-by-side enclosing the antennae. The second and third 
leg pairs lie beneath the expanded tegmina: concealed completely or 
with part of the tarsi projecting. 
It seems probable that in order to achieve this position the mus- 
culature of the tegminal base must be modified in some way and that 
each tegmen would exhibit some structural modification at its base. 
Perhaps some of the movements involved in stridulation require 
muscles and a form of tegminal articulation that facilitate the step 
to this form of profile concealment. 
Figure 2. Stages A, B, and C in the assumption of the full cryptic posture 
(C) of Phyllophora sp. In A the major elements of the third leg are ap- 
posed and the leg is being moved towards the anterior margin of the left 
tegmen. In B the leg is about to be moved under the edge of the tegmen. 
In C the leg has been rotated at its base, moved under the tegmen and the 
tibia now lies closer to the midline of the body than the femur. Note the 
position of the head and antenna in the final stage. 
