1980] 
Stuart & Bell — Leptothorax 
203 
vibrations through the legs, a worker’s antenna was clamped in 
forceps secured above the accelerometer, such that only the ant’s 
legs rested upon the base. Attempts to monitor the airborne 
component of stridulation were made using the initial procedure, 
and by holding the microphone to within 1 cm of the ant. All 
recordings were conducted in a sound attenuating room which 
floats on a concrete, vibration-dampening pad. 
During recording sessions, the ants were observed through a 
dissecting microscope, and were occasionally stimulated with a 
camel’s hair brush, or with air blown through a tygon hose (diam = 
0.5 cm). Stridulatory contexts were determined visually through 
observation of laboratory colonies through a dissecting microscope, 
and under varying conditions as described in the results. Voucher 
specimens have been deposited in the Museum of Comparative 
Zoology, Harvard University. 
Results 
1. Structure 
The stridulatory apparatus of a L. muscorum worker occurs on 
the dorsal surface of the third and fourth abdominal tergites. The 
pars stridens is located in the mid-dorsal region of the anterior 
portion of the first gastric segment, and the plectrum apparently 
consists of the trailing edge of the post-petiole (Figs. 1 and 2). Other 
portions of the worker’s body were examined with the electron 
microscope in an attempt to locate other possible stridulatory 
structures, but none were found. 
2. Signal 
Workers glued to the accelerometer surface responded by persis¬ 
tently pulling and struggling to free themselves. This activity was 
accompanied on an intermittent basis by very characteristic and 
regular dorsoventral movements of the gaster, which occurred in 
short bursts and in more prolonged sequences. During these 
movements a distinct vibratory signal was detected by the accel¬ 
erometer (Fig. 3). The highly characteristic stridulatory movements 
of this species make visual observation through a dissecting micro¬ 
scope a reliable means of determining the occurrence of stridulation. 
The acceleration of the vibratory signal was measured as 1.4 X 10 
m/sec ? RMS (= 1.95 X 10~ 4 m/sec 2 p-p). However, no further 
