A TIBIAL GLAND SCENT-TRAIL AND TRAIL-LAYING 
BEHAVIOR IN THE ANT 
CREMATOGASTER ASHMEADI MAYR. 
By R. H. Leuthold* 
The Biological Laboratories, Harvard University, Cambridge, Mass. 
INTRODUCTION 
Wasmann (1899) speculated that ants might lay odor trails by 
using their feet. But with the exception of a challenge by Brun 
(1914), the footprint hypothesis was laid dormant. In all ant species 
thus far analysed, trail-substances originate from the gaster of the 
ant, whether the instrument is the sting, as in the Myrmicinae, the 
anus, as in the stingless Ponerinae, Dorylinae and Formicinae, or 
the posterior border of the sixth abdominal sternite as in Dolicho- 
derinae (Wilson 1963, Gabba 1967). 
The myrmicine ant, Crematogctster ashmeadi, obviously builds up 
scent trails for communication. However, the gasters of workers are 
never seen to touch the substrate, not even when a new trail is being 
established. The workers often erect the abdomen upward and, 
especially when excited, they even bend it forward superimposed to 
the thorax so that they take on the superficial appearance of a little 
spider rather than an ant. Their sting is often protruded, but it 
never touches the ground. 
Goetsch (1934) observed the peculiarity of the trail-laying of the 
Mediterranean species Crematogcister scutellaris. He also noticed 
that they never touch the substrate with their abdomen. He describes 
the behavior of trail-laying workers as the following: “The ant per- 
forms a kind of dancing step folding its hindlegs”. He suspected 
the pheromone source to be somewhere in the gaster and claimed 
that the trail substance is possibly released as a vapor } the hindlegs 
functioning to support the gaster at a fixed height above the ground. 
The described behavior is compatible with my observations in C. 
ashmeadi , but our interpretations differ greatly. The dancing step 
of the hindlegs, in fact, is a description of trail-laying by footprints. 
It will now be shown that a physiologically functional system of 
trail-laying has evolved in C. ashmeadi that involves the hindlegs, a 
system which early naturalists were thinking about without having 
seen it. 
While this article was in preparation and after my own analysis 
had been completed, there appeared a report by Fletcher and Brand 
^Present address: Zoologisches Institut der Universitat Bern, Switzerland. 
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