4 
Psyche 
[March-June 
include Sao Paulo, Missiones, Espiritu Santo, Matto Grosso, Bahia, 
and Para in Brazil, as well as “Perou.” For the present study, the 
authors selected a single, restricted population of the typical form, 
not far from Para, which they have intermittently had under inde- 
pendent field observation since 1937. Some 30 “workers,” together 
with more than a dozen cocoons and larvae, were taken from a 
typical colony by one of us (PAZ) in December, 1969, and brought 
to Washington, D. C., where they were housed in observation nests 
and the recorded observations made over a period of somewhat 
more than a year. 3 
Methods and Observations 
The colony was approximately evenly divided, and the fractions 
housed in glass-and-plastic earth-containing Lubbock nests, 45.7 cm 
X 28.5 cm, and 3.0 cm in depth. Two of these were stacked in 
each of 2 aquaria of dimensions 61 cm X 29.0 cm X 22.5 cm, to 
serve as foraging arenas. These aquaria were covered at all times 
with 2 glass plates, with an aperture of 1.0 cm, through which was 
inserted the stem of a Weston Mirroband recording thermometer. 
Room temperature was kept constant at 75 0 F. Since the entrances 
to the Lubbock nests were kept open at all times, and soil was 
excavated and carried into the arena fairly continually by the ants, 
humidity usually approached saturation, 
A. Breeding Pattern 
The eggs of D. grandis are comparatively large (approximately 
2.5 mm in length) and unusually elongate. They cohere in packets, 
usually of approximately 6 to 15 ova, and are assiduously tended by 
the workers. Indeed, the nurses spend much time in the nest at rest 
with such packets held in the mandibles. Shortly before hatching, 
single eggs are detached from the packet, licked and tended indi- 
vidually, and commonly deposited separately on the nest floor. Imme- 
diately after hatching the larvae are separately attended and fre- 
quently carried about. We believe (though it is not yet proved) 
that for the first, and possibly the second, instar they are fed in- 
gluvially by the nurses. Older larvae are given partially dissected 
arthropod prey in typical ponerine fashion, the fresh prey being 
commonly deposited on the ventral surface. The larvae develop 
rapidly through this stage. When about to spin, they are temporarily 
covered with earth in the typical ponerine manner. The cocoons of 
3 The authors wish to express their great appreciation to the National 
Geographic Society for its support of certain aspects of the 1969 field work 
in Brazil. 
