14 
Psyche 
[March 
was much better luck than we had any right to expect, 
especially in view of the fact that it was the first nest 
completely dug into, and also that no other queens were 
taken from the colony. Though we tried other nests, no 
further specimens of females of this species were obtained, 
and no winged forms, male or female, were found either. 
The queen was brought to the laboratory and kept in an 
observation nest for four months (until April 2, 1951), 
after which she was preserved. During the period, a few 
eggs were laid but only three workers were reared to 
maturity, and these were all much smaller than the workers 
from the original colony which were brought with the 
queen and kept with her in the artificial nest. No positive 
information was gleaned regarding the species of ant 
which serves as host for the incipient colonies of opaciven- 
tris, but it seems probable that altipetens may function in 
this capacity, owing to the fact that so many nests of the 
latter were present in the pasture where the opaciventris 
colonies were found. We did not turn up any incipient 
nests of the parasitic species, nor did we find any mixed 
colonies of the two ants, though we searched for them. It 
has never been established that opaciventris is truly a tem- 
porary social parasite, and its host is still unknown; how- 
ever, it has been shown that exsectoides and ulkei both 
utilize F. fusca, so it will be no surprise if opaciventris is 
found eventually to use fusca or some related species. The 
well developed trichomes, or brushes of short hairs, on 
the mesonotum of the queen are strong evidence in favor 
of such a prediction. 
Formica opaciventris Emery 
Female : — Length 10.5 mm.; head index 0.96. 
Head subquadrate, almost as wide as long ; sides straight 
but distinctly converging anteriorly; greatest width occurs 
just behind the eyes; occipital border broadly and definitely 
excised. Clypeus entire, with only a slight point at the 
middle of the anterior margin, and an indistinct carina. 
Frontal area well defined and triangular. Antennal scapes 
slender though gradually increasing in thickness toward 
the tips, and surpassing the occipital angles by a distance 
