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Psyche 
[Vol. 85 
Pogonomvrniex behavior, I found activity rhythms of various col- 
ony tasks (Gordon 1983b and 1983c). 
P. hadius has received much less attention than other Pogono- 
myrmex species, perhaps because it is geographically isolated from 
them. Nevertheless, the scanty literature on P. badius behavior con- 
tains some descriptive reports that suggest the existence of activity 
rhythms in this species as well (Van Pelt 1966, Hangartner et al. 
1970). The present study was made in the laboratory. In this way, 
activity rhythms could be investigated more systematically than 
would be possible in a field study. 
Methods 
Four queenright colonies (colonies 1, 2, 3, and 4), each containing 
300-600 workers, were observed for 30 days from March 1, 1983 
through April 2, 1983. Colonies were kept in open, soil-filled terra- 
ria, and fed Bhaktar-Whitcomb (1970) diet or chopped mealworms. 
The study colonies had all been kept in the laboratory for about one 
year. They were chosen for the study because they had been consist- 
ently active and healthy since being brought into the laboratory. 
The laboratory temperature was maintained at 27° C (±1°). 
Observations of each colony were made 5 times daily, once in 
each of five 100-minute time periods, as follows: Time period 1 
(TPl), 9:50-11:30; TP2, 11:30-13:20; TP3, 13:20-14:50; TP4, 
14:50-16:30; TP5, 16:30-18: 10, and usually in the middle of the time 
period at the following five times; 10:40, 12:20, 14:00, 15:40 and 
17:20. Overhead fluorescent lights in the laboratory were on from 
7:30 to 23:00. A lamp with a 60 watt bulb was placed from 30 to 50 
cm above each colony as a heat source. These lamps were illumi- 
nated daily from 1 1:30 until 16:30. Thus, during the first and last 
observations, room lights but not individual lamps were on; during 
the 2nd-4th tjrfie periods, individual lamps were on as well. Temper- 
atures on the terraria surfaces, both under the individual lamps and 
at other points on the opposite side of the tanks, were measured 
with a thermistor (Yellow Springs Instrument Co. #408). Tempera- 
ture measurements were made in the terraria of the four study 
colonies and also in those of four other colonies maintained in an 
identical manner. The colonies were fed every other day imme- 
diately after the 12:20 observation. 
