206 
Psyche 
[Vol. 87 
to brood, and under normal conditions, is not accompanied by 
stridulation. However, if colonies are deprived of food and water for 
5-7 days, workers grooming other adults and larvae will frequently 
stridulate. It is possible that secretions are being obtained from the 
body surfaces, and that under such stressful conditions provide 
sufficient stimuli to induce stridulation. 
F. Brood Manipulation 
In attempting to manipulate or move larvae, workers occasionally 
encounter a larva which has become securely stuck to the floor of 
the nest. Workers respond to this resistence by pulling on the larvae, 
and frequently stridulate as they do so. In this context stridulation is 
associated with pulling, as it is when fighting or feeding. Neverthe¬ 
less, all of these situations represent different behavioral contexts, 
and have therefore been considered separately. 
Discussion 
L. muscorum workers possess a well defined stridulatory ap¬ 
paratus, similar to that of certain other ponerine, myrmicine and 
pseudomyrmecine ants (Markl, 1973). When restrained, L. muscor¬ 
um workers display characteristic dorsoventral movements of the 
gaster which are associated with, and apparently induce, weak 
vibrations in the substrate, but no detectable airborne sound. This 
vibratory signal is transmitted to the substrate through the ant’s 
legs. Similar stridulatory movements are observed when workers are 
fighting, dissecting insects, engaging in trophallaxis with adults and 
larvae, and when attempting to move larvae that adhere to the 
substrate. Furthermore, in food and water deprived colonies, 
stridulation occurs when workers groom other adults or larvae, or 
consume liquid food or water. Although the function of stridulation 
during the above contexts remains unknown, the intermittent 
nature of this behavior during all of these activities indicates that it 
is not an essential component of any of them. 
Markl (1970) found that small workers of Atta cepholotes were 
more sensitive to stridulatory vibration than large workers. The 
minimum threshold for vibration reception in these small workers 
was 2.5 cm/ sec 2 (p-p) (sic) acceleration. In this study, the accelera¬ 
tion of the L. muscorum stridulatory vibrations was 1.95 X 10” 6 
cm/sec 2 (p-p). The small size of L. muscorum workers probably 
