1978] 
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pygidial gland has already been identified. In Novomessor cockerelli 
and N. albisetosus the strongly smelling secretion of the pygidial 
glands releases a “panic alarm” response in workers, apparently 
specifically designed against army ant predation (Holldobler in 
prep.). Kugler (in press) demonstrated that in Pheidole biconstricta 
the pygidial glands produce an alarm-defense secretion. A quite 
different function has been discovered in Rhytidoponera metallica. 
Here the wingless virgin females attract males by the release of a 
pheromone from the pygidial gland (Holldobler and Haskins 1977). 
Since Rhytidoponera workers also have a well-developed pygidial 
gland and are attracted to its secretions, we believe we have not yet 
discovered the whole functional spectrum of this organ. In Lepto- 
genys chinensis, Maschwitz and Schonegge (1977) demonstrated 
that the pygidial gland secretions serve together with poison gland 
substances as a recruitment trail pheromone. We obtained similar 
results when we recently reexamined the anatomical source of the 
trail pheromone of Paehycondvla ( =Termitopone ) laevigata. This 
ant species conducts well organized predatory raids on termites. 
During raiding the workers move in a single file, one closely behind 
another, along a powerful trail pheromone laid down by leading 
scout ants. Blum (1966) has identified the hindgut as the source of 
this recruitment trail pheromone. We cannot confirm his findings. 
In our experiments with artificial trails laid with extracts from 
several abdominal glands, only the pygidial gland secretions re- 
leased massive trail-following behavior in P. laevigata (Holldobler 
and Traniello in prep.). A careful observational study of the trail- 
laying behavior of P. laevigata workers revealed that not the anus 
but rather the pygidial gland is dragged over the ground. Although 
the pygidial gland of P. laevigata has no definite reservoir, it is very 
well developed and is associated with an elaborate cuticular struc- 
ture on the 7 th tergum (Fig. 19, 20). The glandular secretion is 
apparently stored in the many cavities of this structure. When 
trailing, the ants rub this structure with its special applicator surface 
over the ground and deposit thereby the trail pheromone. Traniello 
(pers. communication) observed species of Odontomachus during 
nest emigrations performing the same trail laying behavior. We 
suspect that in Odontomachus also the pygidial gland secrets a trail 
pheromone (Fig. 21). 
In Bothroponera ( —Pachycondyla ) tesserinoda we previously 
analyzed the signals involved in the tandem running recruitment 
technique (Holldobler et al 1973, Maschwitz et al 1974). We 
