14 
Psyche 
[Vol. 88 
predaceous, decticine grasshopper-prey rather than beak marks of 
some bird. 
Chemical defenses: regurgitated fluid (R) 
Chemical defenses are particularly widespread among insects (see 
for instance Eisner and Meinwald 1966; Wallace and Blum 1971, 
etc.) including Opthopterans. Some of them have specialized glands 
and the substance can be ejected with considerable force (e.g. 
Poekilocerus buforus, from an opening located on the first abdom- 
inal tergite: Fishelson 1960). A froth can also be discharged through 
a thoracic spiracle (e.g. Romalea microptera: in Eisner and Mein- 
wald 1966). Such repellents make their owner distasteful or un- 
palatable. The same apparently holds for fluids regurgitated from 
the gut through the mouth (Edmunds 1974, p. 199) by grasshoppers 
for instance = enteric discharges (Matthews and Matthews 1978, p. 
335). Digger wasps, however, do not consume their prey usually but 
avoid contact with this fluid which is apparently a contact repellent. 
Functioning of the receptors located around the stinger could be 
impaired (jamming effect?) chemically and/or mechanically (Steiner 
1976). Stinging remains possible, however, even with stinging sites 
covered with the fluid (Figs. 2 and 5b) but the wasp clearly hesitates 
or even gives up half way through stinging. Contact triggers 
vigorous, sometimes frantic, rubbing against the ground and/or 
hyper-grooming as in ants (Matthews and Matthews 1978, p. 335) as 
in hunters of regurgitating caterpillars like cutworms (e.g., Am- 
mophila, Podalonia wasps). Body contact is clearly unpleasant if 
not deleterious, particularly for some small Tachysphex wasps 
(Steiner 1976). 
One of the latter ( tarsatus No + 874) had her abdomen tip covered 
with a thick coat of sand particles as a result of her attempts to rub 
off the sticky substance. The wasp was found dying the next day, 
June 19 (Arizona study) (the same probably happened to another 
tarsatus (No + 887) which died on June 6). 
The same wasp (No + 874) was also observed the day before (June 
18, 1405 h) in the process of carefully removing with the mandibles, 
bit by bit, a large crust of dried up fluid, from the ventral surface of 
the thorax and throat of a grasshopper. This was done right after 
“malaxation” of the fore leg bases which in some larrine wasps is a 
preparatory stage of egg-laying (details in Steiner 1971). Since the 
