AUDIO MIMICRY: AN ADJUNCT TO COLOR MIMICRY 
By Albro T. Gaul 
Brooklyn, New York 
During the summer of 1951, while I was working on 
some aspects of Vespine wing muscle physiology, I had 
the opportunity to study some of the wing sounds of certain 
Vespine mimics. The work was done at Windsor, Mass., 
with specimens of Dolichovespula arenaria F. (Vespidae) 
and Spilomyia hamifera Lw. (Syrphidae). A comparison 
of the wing tones of these two species has led to the follow- 
ing considerations. 
In color pattern, this fly bears a very close resemblance 
to the wasp, although the abdomen of the fly is somewhat 
more robust. It is very difficult for me to tell these species 
apart when they are in flight. Even when the insects are 
at rest, the longitudinal fuscous band along the wing of the 
fly makes visual determination difficult without close scru- 
tiny. It is not known just what, if any, function is served 
by this likeness; nor can it be definitely determined which 
insect is the mimic and which the model. It is not a unique 
relationship between the two genera, since Spilomyia fusca 
Lw. closely resembles Dolichovespula maculata Linn, in 
size and color pattern. 
The original wing experiments involved the use of a 
microphone and an electro-mechanical transducer to pick 
up wing beat tones and thoracic vibrations. The output 
from these instruments was played through a high fidelity 
preamplifier and amplifier system and was then led into the 
input terminals of either an audio-frequency meter or an 
oscilloscope. With either instrument it was possible to 
measure the wing-beat frequencies of the insects. A direct 
comparison of frequencies was therefore made between 
the wing tones of S. hamifera and D. arenaria. The more 
or less standard wing frequency of workers of arenaria is 
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