1981] 
Steiner — Anti-predator Strategies 
9 
The eliciting stimuli of such reactions could not be determined, 
because of the suddenness and unpredictability of such encounters. 
Sight of the rapidly approaching predator and/or mechanical 
contact are likely candidates. 
b) Observations in captivity (Figs. 3 and 4) 
Similar or identical responses were also observed in captivity at 
close range and in better conditions. Confinement seemed to even 
somehow favor appearance of this behavior perhaps because of 
restricted escape and/or greater concentration of attacks. Often the 
extended wings and whole body were also strongly curved down- 
wards, sometimes even tightly pressed against the substrate (Fig. 3). 
The appendages and head were tucked in and more or less invisible 
under the protective “umbrella” of the wings. The sudden flash of 
the colorful wings and dark semi-circular markings, followed by the 
appearance of convulsive movement and finally the illusion of a 
disabled or dying grasshopper were, indeed, an arresting sight, at 
least for a human observer. 
Curiously such frozen grasshoppers mostly failed to suddenly 
“resuscitate” and escape after it had become evident that their 
postural defense had failed to stop the wasp attack. Such misfiring 
might be a cost of this strategy because of the strong inhibitory 
influences apparently involved. Sometimes wing fluttering resumed 
as the wasp attempted to deliver the paralyzing stings. If left alone 
by the wasp the grasshoppers would however invariably recover 
without any sign of discomfort, like in the wild. 
Such displays were never observed with Tachysphex wasps, 
perhaps because the much smaller grasshopper nymphs they attack 
have undeveloped wings . . . that cannot be used. 
If the Prionyx wasps succeed in overcoming all these various 
defense mechanisms or hurdles, as they often do, they then attempt 
to deliver an average four successive stings, always on the same 
stinging sites and in a predictable order (summarized in Steiner 
1976; details in Steiner 1981). The paralyzed grasshopper can then 
be safely and freely manipulated and stored in the nest, without any 
resistance, obstruction. 
Analysis, Discussion, Comparisons 
Discussion is concerned mainly with possible or plausible inter- 
pretations and evolutionary significance of these various defense 
