1952] 
Gaul — Audio Mimicry 
83 
150 strokes per second ; while that of hamifera is 147 
strokes per second. This places both tones between D and 
D # . These readings were made with 42 arenaria workers 
and 8 hamifera adults. The accuracy of the meter was 
within 1 cycle per second, at this low frequency range. The 
variation in the wing beats was within plus or minus 2 
strokes per second. Temperature is probably not a factor 
in wing frequency in insects of this size 1 . 
With the average wing beat differing by only 2 strokes 
per second, or 1.33%, it is apparent that the average per- 
son, including the author, can detect no significant differ- 
ence in the sounds produced. Even close attention to 
sound recordings of the two species cannot show any ap- 
preciable distinction. It is thus apparent that there is a 
new form of mimicry, the mimicry of sounds, which in 
one case at least accompanies color mimicry. 
There is little evidence that the color mimicry of these 
wasps and flies serves any particular function. Perhaps 
there is common protection against predators, who have 
only to learn one color pattern. The introduction of sound 
mimicry into the picture forces us to accept one of two 
possible conclusions. Either the similarity of wing tone 
is a chance phenomenon, or we must postulate a significant 
function to this similarity of wing beats. In the latter case, 
we should further have to show that certain predators of 
Spilomyia and Dolichovespula can detect their prey through 
sound ranging but are unable to detect the differences 
which exist between the two sound mimics. 
1 Gaul, A. T. A Relation Between Temperature and Wing Beats. 
Bull. Brooklyn Ent. Soe., 46: 131-133, 1951. 
