214 
Psyche 
[September 
odor (Rettenmeyer, 1961) and surely must serve some similar useful 
function because it is practiced by several different species of staphyl- 
inids (all Dorylomimini) and at least three species of histerids. The 
rubbing by Diploeciton calmed the ants being groomed and several 
ants groomed in this manner even seemed partially paralyzed. This 
condition of paralysis has been reported previously for ants rubbed 
by histerids (Akre, 1968). Although the beetles were observed for 
long periods of time, no function was found for the filiform process 
on the petiole. 
The staphylinid spent an average of 46 seconds grooming each 
ant (20 timed observations) and moved constantly from one ant to 
another. During infrequent periods of inactivity, the beetle was 
usually buried near the bottom of a large cluster of ants that was 
always present over the brood. The entire cluster remained stationary 
for periods up to several hours during these rare moments. 
The staphylinids also groomed at intervals by running their 
antennae and front legs through their mouth parts. Although the 
globular portion of the abdomen was held 45 0 from the perpendicular 
when the staphylinids ran, the abdomen was held perpendicular or 
tilted slightly forward when grooming ants (Fig. 1). The 3-seg- 
mented petiole gives the abdomen considerable maneuverability and 
it can be thrust forward a considerable distance. The beetle rubbed 
the tip of the abdomen on the elytra quite frequently, a practice 
which also seems widespread among the ecitophilous staphylinids 
(Akre and Rettenmeyer, 1966). 
Like other guests of army ants, Diploeciton fed on the brood of 
dolichoderine ants given to the N. pilosus as food as well as on 
army ant brood. However, the staphylinids were observed eating 
N. pilosus brood only three times, and may eat it only when booty 
is not available. They were extremely efficient in cutting open brood 
and, as reported previously (Akre and Rettenmeyer, 1966), the 
beetles were usually driven away by worker ants trying to get at 
the oozing juices. 
The captured beetles behaved nonspecifically towards one another, 
in that the beetles antennated vigorously upon meeting but they 
always continued on their way. They were never seen grooming one 
another or in any intimate contact. 
SUMMARY 
The behavior of Diploeciton nevermanni is similar to that reported 
for several other ecitophilous staphylinids in that the beetles assume 
a unique position in grooming their host, Neivamyrmex pilosus. 
