1981] 
Steiner — Anti-predator Strategies 
11 
Fig. 5: Summary of oedipodine grasshopper anti-predator actions and Prionyx- 
prey interactions, a: the wasp detected a grasshopper which is at the preparatory 
stage of jumping (J); b: the prey flies away (F), suddenly opening very colorful wings 
with conspicuous semi-circular dark markings (startle display) and in some cases the 
wasp follows the grasshopper in flight and even stings it in midair; c: the escaping 
prey suddenly lands and blends with the substrate (crypsis); d: instead of escaping the 
grasshopper sometimes “freezes” into an odd posture somewhat remindful of an 
inhibited flying action; the posture and convulsive wing fluttering give the impression 
that the orthopteran is disabled, dying (disablement display? thanatosis?); at the same 
time the posture and hunching appear to emphasize the semi-circular dark markings 
on the wings (eyespot intimidation display, “bluff’?); furthermore in this posture, 
access of the vulnerable ventral side of the thorax, where stings are delivered, is 
reduced or impossible for the wasp (obstruction behavior); e: hind leg raising ( HLR) 
is another obstructive behavior that makes initial posturing of the wasp difficult or 
impossible; kicking can also send the wasp a few cm away; f: hind legs are also used 
for brushing (B) and/or pushing away (P) the wasp; pressure is applied on the circled 
areas so as to try to force the wasp to release her mandibular and leg grip; g: as a last 
ditch defense the grasshopper can release a repellent fluid through the mouth, which 
rapidly spreads over the ventral thoracic surface where all stinging sites are located; 
the wasp often hesitates to dip into this pool her abdomen tip (circled); the latter is 
also exposed to powerful bites from the grasshopper; therefore the throat of the prey 
must be quickly stung to stop these mouth-based defenses. Solid and dashed arrows 
indicate prey and wasp movements, respectively; open arrows show possible 
sequences of events but these sequences can also be broken if the defenses are 
effective and the wasp gives up. 
