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Fig. 1. Two views of the calling burrow of Scapteriscus borellii with the
approximate location of the gas sampling tube. The single, oval-shaped opening
acts as an approximately 1/3-wavelength radiator set in an infinite baffle.
The horn matches the radiation impedance of the insect's acoustic radiator
(tegminal harps) with that of the opening of the burrow. Males sing as shown
from the constricted region with their heads facing into the burrow and their
elevated tegmina largely filling the space above the cricket. The bulb is a
straight or curved blind-ended burrow 1/4-wavelength in length with an opening
to the main burrow in its side wall. The insect's harps are doublet sources
and sound broadcast from their dorsal (anterior) surface into the bulb is
reflected and then returns to the harps in phase with the sound emitted being
emitted into the horn. Thus, the dimensions of the burrow, calling position of
the insect, and acoustical properties of the burrow walls are all crucial to
the system's performance (Bennet-Clark
1970,
1987;
Daws et al., 1996). Figure
modified from Bennet-Clark
(1989) and used with
permission.
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