1981] 
Holldobler, Moglich, & Maschxvitz — Pella 
357 
The hunting behavior of the beetles was always the same in P. 
laticollis, P. funesta and P. humeralis : the beetle attacked from 
behind and always attempted to insert its head between the head 
and thorax of the ant. We inspected several ants which had just been 
immobilized by an attack of a beetle and found that in most cases 
the pronotum was widely separated from the head and usually the 
oesophagus and connectives of the nervous system were cut. 
Occasionally we observed 2-3 beetles chasing behind one ant 
(Fig. 4). Once the ant was caught by a beetle the other beetles joined 
in subduing and killing the ant. Although individual beetles often 
tried to drag the prey away from the rest of the “hunting pack”, 
usually several beetles fed on the prey simultaneously. No aggres- 
sion among the beetles was observed in this situation. However, 
when the beetles were starved for several days and were kept 
without ants, they occasionally chased each other, jumping on each 
other’s back as they normally did when hunting ants. But we never 
saw cannibalistic behavior among the adult beetles, even when the 
beetles were densely crowded around a prey object (Fig. 2B). 
Defense and appeasement behavior in adult beetles 
Defense with tergal gland secretion: 
Usually the Pella beetles run around with their abdomen curved 
slightly upwards. When encountering an ant, the beetles flex the 
abdomen even more strongly. This is a typical and frequently 
described behavior of many staphylinid myrmecophiles and is 
commonly considered a defense response (Wasmann 1886, 1920; 
Jordan 1913; Patrizi 1948; Koblick and Kistner 1965; Pasteels 1968; 
Holldobler 1970, 1972; Kolbe 1971). It has been suggested that 
during this abdominal flexing the beetles discharge secretions from 
their tergal gland (Jordan 1913; Kistner and Blum 1971). 
The tergal gland is located between the sixth and seventh 
abdominal tergites (Fig. 6), and is unique to the subfamily Aleo- 
charinae (Jordan 1913; Pasteels 1968). The chemistry of the tergal 
gland secretions of several species has been investigated and found 
to be extraordinarily diverse (Blum et al. 1971; Brand et al. 1973; 
Kolbe and Proske 1973). 
Kistner and Blum (1971) suggested that Pella japonicus and 
possibly also P. comes , both of which live with Lasius spathepus, 
produce citronellal in their tergal glands. This substance is also a 
