1968] 
Evans — Neotropical P ompilidae 
9 
of these two species will be found to have black bodies, partially 
orange antennae, and largely orange wings: that is, that they will 
be “ Pepsis mimics” like those of other members of this species group. 
One is, of course, curious to know what selection pressures pro- 
duced males that are Batesian mimics of social wasps and females 
that are Mullerian “P^ffj-mimics”. As pointed out earlier, the males, 
in their irregular searching flights, remain mostly well above the 
ground, chiefly in herbs and bushes that may contain workers of 
social wasps. At the same time the females spend the greater part of 
their time on the ground searching for spiders, in the same habitat 
as the various orange-winged species of Pepsis P riocnemioides , and 
other genera. It is true that orange wings like those of the females 
seem to serve the males of most related wasps perfectly well: pre- 
sumably birds and lizards learn to avoid this color and do not dis- 
criminate between the sexes. Evidently the males of these species of 
Chirodamus have achieved a still more effective level of protection 
by resembling certain common social wasps. It is probable that other 
cases of marked color dimorphism, such as in the genus Austrochares 
and in certain Scoliidae and Ichneumonidae, as mentioned earlier, 
reflect the fact that males and females spend the greater part of their 
time in slightly different situations, such that selection has favored 
a different mimetic pattern. 
In complexes such as these the distinctions between Batesian and 
Mullerian mimicry and between the latter and generalized aposematic 
patterns are obviously unclear. I have spoken of male Pepsis as 
Batesian elements in their complex, but the fact is that both sexes of 
at least some species of Pepsis have a characteristic odor, and this 
odor may well be repellant to predators. Similarly, the odor of the 
slow-flying ichneumon Ephialtes may serve to reinforce its mimicry 
of social wasps — a bird that “forgets” the mimetic pattern is re- 
minded, not by a sting, but by a chemical stimulus. It is probable 
that many male and non-stinging female Hymenoptera are not fully 
palatable. Furthermore, many males, when seized, undergo move- 
ments of the abdomen suggestive of stinging, and in several groups 
the genitalia or apical sternite have evolved into a pointed “pseudo- 
sting”, often capable of pricking but never supplied with poison 
glands. That “palatability” is no simple phenomenon has been further 
shown by Brower et al (1967), who found that some races of the 
monarch butterfly are actually palatable “automimics” of distasteful 
members of the same species that have fed as larvae on poisonous 
species of milkweeds. 
