1956] 
Wilson — Rhopalothrix biroi 
23 
the ants “froze” in their movement, drew their antennae 
part way back (but not all the way against the head), 
and opened their mandibles maximally, that is, to the 
extent where the tips were about as far apart as the 
width of the clypeus. This was followed by a slow, cautious 
movement toward the prey. On one occasion a worker 
was seen to lunge and snap at an entomobryid immediately 
upon making contact, but careful stalking is probably the 
rule, as it is in the short-mandibulate dacetines. 
Prey were carried into the brood chamber directly after 
capture; only once was a worker seen to feed on an 
entomobryid at the spot of capture. Captured animals 
were either left on the brood chamber apart from the 
larvae, or else placed immediately among the larvae, which 
fed on it directly, ponerine fashion. The adults fed sep- 
arately or simultaneously with the larvae on the same 
animal, as I have observed many times in the dacetine 
genus Smithistruma. 
While they behaved in an alert, aggressive manner 
toward potential prey, the Rhopalothrix reacted toward 
potential enemies, such as larger staphylinid beetles, by 
lowering the head, retracting the antennae entirely, and 
keeping the mandibles closed. One worker, knocked over 
by a beetle walking past, was seen to draw in all of its 
appendages and feign death. 
The workers were very solicitous of the brood, wash- 
ing it and moving it about constantly. They were in fact 
more attentive in this way than any dacetine genera I 
have studied. Adult oral trophallaxis was observed twice; 
the workers faced one another and twisted their heads 
slightly sidewise to approximate mouthparts. The adults 
also licked one another’s bodies constantly. Once I saw a 
worker standing rigidly still, while a second worker 
curled around its upraised head and gave the mouth- 
parts, gula, and prosternum a thorough washing. Adult 
transport was observed once. The transporter gripped 
the transportee’s pedicel from below, while the transportee 
folded in its appendages pupal fashion. Later the trans- 
porter shifted its grip so that one mandible rested on the 
gaster. 
