4 
Psyche 
[Vol. 93 
vate nests. Laboratory observations demonstrated that this can be 
followed by normal haplometrotic colony development. 
Both the R. metallica and R. chalybaea queens readily accepted 
the plaster-of-Paris nests, and began raising worker brood. The 
queens of both species foraged in their arenas for food, and accepted 
both honey and fresh arthropods. Struggling Drosophila adults 
(held in the foraging arena with a pair of fine forceps) were 
approached with outstretched mandibles, captured, stung, and 
returned to the nest. 
The R. metallica queens appeared to be no less dexterous than the 
R. chalybaea queen in capturing and handling prey, or in caring for 
larval brood. As the larvae matured, queens of both species used 
sand grains to construct cocoon-spinning matrices for the larvae. 
Initially the development of brood proceeded at a similar rate in all 
three colonies, with eggs, larvae, and cocoons present by the tenth 
week (late November, 1983; Table 1). 
Some behavioral differences were noted between the two species: 
the R. metallica queens were observed foraging more frequently 
during daytime hours than the R. chalybaea queen; the R. metallica 
queens established their middens in the nest entrance, thus partially 
closing it, whereas the R. chalybaea queen scattered most of her 
refuse just outside the nest entrance; and the R. metallica queens 
defecated widely (frequently in the foraging arena) whereas the R. 
chalybaea queen concentrated her fecal deposits at one location (c. 
25 mm 2 ) inside the nest chamber. These minor (and perhaps idiosyn- 
cratic) differences hardly diminish the overriding similarity between 
the two species in early colony development. 
After about twelve weeks, and just prior to the eclosion of 
workers, colonies of the two species of Rhytidoponera began to 
diverge in their patterns of development. The first R. metallica 
workers appeared to have difficulty eclosing from their cocoons — 
possibly because of inept assistance on the part of the queens — and 
there was appreciable early worker mortality both as pharate adults 
in cocoons and as eclosed adults. No such difficulties were evident in 
the R. chalybaea colony, whose worker population increased at 
considerably faster rate than that of the two R. metallica colonies 
(Table 1). Moreover the R. chalybaea colony displayed regular 
(although increasingly dampened) cycles of brood development, 
with bouts of egg-laying followed by pulses of larval growth, cocoon 
formation, and adult eclosion, whereas such cycles appeared to be 
