16 
Psyche 
[Vol. 89 
From the ants’ orientation behavior it appeared that they were 
following chemical trails during the nest emigration. In fact, the 
recruitment behavior during nest emigrations and raiding appeared 
to be identical. The following experiments were designed to analyze 
further the communication mechanisms involved in both events. 
Communication during emigration and raiding 
Two distinct behavioral patterns were observed in Cerapachys 
ants during recruitment. (1) They seem to lay a chemical trail when 
returning from the target area (prey colony or new nest site) by 
frequently touching the abdominal tip to the ground; and (2) when 
close to or just entering the nest, they repeatedly raised their gaster 
upwards into a “calling position” and continued to do so when they 
moved back to the target area, usually being closely followed by a 
group of recruited nestmates. Since it was easier to initiate emigra- 
tions rather than raids, most of the experiments were conducted 
during colony emigration. Several new exocrine glandular struc- 
tures have recently been discovered in ponerine ants (Holldobler 
and Haskins 1977; Holldobler and Engel 1978; Holldobler et al. 
1982; Maschwitz and Schonegge 1977; Jessen et al. 1979). The 
Cerapachyini were not included in these studies. We therefore con- 
ducted first a histological survey for possible exocrine glands that 
might be involved in the communication behavior of Cerapachys. 
Besides the known glands associated with the sting, we found a 
pygidial gland, which consists of a paired group of a few glandular 
cells under the 6th abdominal tergite. Each cell sends a duct through 
the intersegmental membrane between the 6th and 7th tergite (Fig. 
9). The intersegmental membrane is laterally slightly invaginated, so 
that at each side it forms a small glandular reservoir. No particular 
cuticular structure on the pygidium is associated with the pygidial 
gland. 
In a first set of pilot experiments I dissected out of freshly killed 
Cerapachys workers poison glands, Dufour’s glands, hindguts, 
pygidial glands (6th and 7th tergites) and the last 3 sternites. For 
each test one organ of a kind was crushed on the tip of hardwood 
applicator sticks. These were then immediately inserted into the nest 
tube until the tip of the applicator was 2-3cm away from the colony, 
