260 
Psyche 
[September-December 
Double mimicry. 
The third and final example of a defensive adaptation involves 
mimicry. Mimicry is highly developed in the Cerambycidae (e.g., 
Gahan, 1913; Shelford, 1902, 1916), and has been well-reviewed 
by Linsley (1959a, 1959b, 1961). We here draw attention to Acv- 
phoderes sexualis Linsley, a cerambycid that appears to mimic 
two different groups of stinging Hymenoptera, wasps and ants. 
At rest, and especially when walking about, Acvphoderes sexu- 
alis (Figure 3A-3C) bears a striking resemblance to a large pone- 
rine ant, such as Paraponera clavata. The resemblance is produced 
by the following adaptations: The antennae are short (for a ceram- 
bycid) and are moved in an antlike manner. The elytra are ab- 
breviated and swollen at the base, enlarging the apparent thorax. 
The hindwings are heavily infuscated and are not folded beneath 
the elytra at rest, but rather are clipped in place by the elytra on 
the abdominal dorsum, where they are tightly twisted along the 
petiolate basal part, and expanded apically to produce the effect 
of a large dark gaster. The beetle’s behavior convincingly adds 
to the resemblance of a ponerine ant. Upon being grasped, the 
beetle makes stinging movements with the abdomen. Since the 
abdominal apex is quite hard and sharp, the sensation of an im- 
pending sting is quite effective. Moreover, like many ponerine 
ants, the beetle stridulates when handled. 
Upon taking flight, the appearance of the beetle changes sud- 
denly to that of a wasp (Figure 3D-3F). For a moment the dark 
hindwings are raised at an angle to the body, and the “petiole” 
and “gaster” are slightly reduced in apparent size. The petiole 
now appears very thin, and the gaster more bulbous. This ap- 
pearance is retained during flight, when the wasplike effect is 
enhanced by the hanging legs. The “wasp” is seen momentarily 
upon landing, just before the hindwings are again clipped in place 
by the elytra and the “ant” suddenly reappears. 
There are many different wasp species that could potentially 
serve as models, especially the numerous and aggressive dark 
polybiines, such as Polybia rejecta. The beetle is therefore pre- 
sumed to be a “group mimic” of large, dark ponerine ants and 
medium-sized, dark vespoid wasps, two of the most abundant, 
conspicuous, aggressive, and best-defended insects in neotropical 
rain forests, including Barro Colorado Island. We have no in- 
formation as to the palatability of the beetle. 
