1981] 
Holldobler, Moglich, & Maschwitz — Pella 
353 
In any case, Pella larvae are able to come into close contact to 
workers of L. fuliginosus without being attacked, especially when 
the temperature is low (14-17° C). Under those circumstances we 
have seen the beetle larvae licking the cuticle of live ants, including 
even the mandibles and mouthparts. This led us to the question of 
whether the beetle larvae occasionally solicit regurgitation in ants. 
In order to investigate this possibility ants were fed with honey- 
water labeled with the isotope 32 P and then housed together with 
beetle larvae. For each sample we kept 30 radioactive ants with 5 
beetle larvae in plastic containers (10 X 15 cm) with a moist gypsum 
bottom. One experimental series was conducted in a temperature 
range of 14.5-16.5° C, the other in 20-23° C. After 24 hours we 
measured the amount of radioactivity in each individual ant and 
larva. No significant amount of radioactivity had been transferred 
from the ants to the larvae, except in container 6, where one ant was 
found dead and obviously partly eaten by the larvae. Since the 
amount of radioactivity carried by some of the larvae was only very 
slightly above the background activity, we concluded that it was 
transferred by contamination. From this experiment it appears that 
the Pella larvae do not solicit regurgitation in ants. Their main food 
source seems to be dead ants or debris of the ants. In fact, they can 
easily be raised by keeping them entirely separated from living ants, 
just by feeding them regularly with dead ants. 
Predatory behavior of adult beetles 
Since Wasmann’s early observations (1886, 1920, 1925) very little 
has been reported concerning the biology of the myrmecophilous 
Pella. Wasmann reported that all species he had studied (P. 
humeralis, P. funesta, P. cognata, P. similis, P. lugens and P. 
laticollis ) live with Lasius fuliginosus , and only P. humeralis can 
also be found with species of the Formica rufa group. According to 
Wasmann all these Pella species prey on ants, concentrating espe- 
cially on disabled ants. In addition Wasmann observed that the 
beetles are active primarily during the night. In a more recent 
publication Kolbe (1971) failed to find a predatorial behavior in P. 
humeralis and concluded that this species primarily feeds on dead 
ants. Similar observations were made with Pella japonicus, which 
lives with Lasius spathepus (= L. fuliginosus var. spathepus 
Wheeler) (Yasumatsu 1937; Kistner 1971). Kistner also observed 
that these beetles “ate small insects that are being transported by the 
