1983 ] 
Rissing — Pogonomyrmex colei 
323 
trace of rain. No flights of either species were observed at 35 nearby 
P. rugosus nests during this time. On 8 October 1979 I poured 
approximately 7.5 1 of water directly onto the host nest crater 
resulting in an immediate flight of P. colei. This procedure was 
repeated unsuccessfully on 17 and 18 September 1982. Viability of 
the host nest (as determined by worker activity, size of crater and 
refuse pile, and absence of plants growing in the crater) has 
remained constant and similar to that of nearby P. rugosus colonies 
from 1978 to 1982. I have never observed any forms that might be 
considered P. colei workers. 
Colony foundation. Ten newly mated P. colei females from the 15 
September 1978 flight were placed into a 7.5 m high flight enclosure 
made of plastic sheeting and permitted to fly. Subsequent to this all 
females removed their wings but did not dig burrows when placed 
into laboratory nest boxes containing moist sand. Five of these 
dealate inquilines were transferred to 5 laboratory nests containing 
only newly mated P. rugosus queens. These P. rugosus queens had 
been collected one week earlier at a mating site 3.2 km from the host 
nest making it unlikely that they were related to the host colony. 
Four of these laboratory nests contained a single, mated dealate P. 
rogusus queen; the fifth contained two P. rugosus queens. The P. 
colei queen added to the nest with two P. rugosus queens was 
immediately attacked and removed from the glass tube occupied by 
the P. rugosus queens. Of the P. colei queens added to the single 
queen P. rugosus colonies, one was found dead within several hours 
(decapitated), and the other was found dead (entire) 5 d later. The 
other two P. colei queens lived peacefully along side the P. rugosus 
queens for at least a month. During this time I frequently observed 
the P. colei queens grooming the P. rugosus queens; P. rugosus 
queens did not reciprocate. These last two colonies ultimately failed 
during (or possibly in response to) transportation from Boulder City 
to Seattle. 
Five other newly mated, dealate P. colei queens were released in 
the field at the entrance of large, active P. rugosus colonies near the 
host nest. Inquilines were always removed immediately from the 
nest by one or more workers and dropped several meters from the 
crater. The P. colei queens made no attempt to re-enter these nests 
following removal. 
