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[Vol. 88 
major compound of the mandibular gland secretions of their host 
ants, for which it functions as an alarm pheromone. Although no 
Pella tergal gland contents were available for chemical analysis, 
because irritated beetles seemed to smell like the ants’ mandibular 
gland secretion, Kistner and Blum speculated that Pella produce in 
their tergal glands citronellal and thereby mimic the alarm phero- 
mone of their host ants. They suggested that in this way the beetles 
can “cause the ants to reverse their direction; a reaction which 
allows the myrmecophiles to escape”. 
Our investigations of the defensive strategy employed by the 
European Pella towards their host ants Lasius fuliginosus led to 
m ]j 
Fig. 6 Schematical drawing of a Pella beetle indicating the position of the 
exocrine glandular complexes. TG: tergal gland; AG: appeasement gland complex. 
