322 
Psyche 
[Vol. 90 
Observations 
Mating Activities and Season. Five P. colei males were collected at a 
single P. nigosus nest during the morning of 13 August 1978; a 
series of thunderstorms and rain had occurred 12 hr earlier. 
Frenzied host worker activity suggested a mating flight or similar 
activity occurred immediately prior to my arrival. No flights of 
either species occurred at any nearby P. rugosus nests observed 
simultaneously. 
I observed a complete inquiline and host flight at this same nest 
on 15 September 1978 following an extensive rain storm the 
preceding day. Flights were occurring at 2 of 23 nearby P. rugosus 
nests; P. colei was not found at any other nest. Mating activities 
began with accumulation of several hundred host workers in and 
around the nest crater. These workers pugnaciously defended the 
area throughout both flights as is typical during P. rugosus flights 
(Rissing, personal observation). As ground and air temperatures 
increased male P. colei climbed to the crater and were soon joined 
by much larger females. While both sexes of P. colei are winged, 
mating occurred at the nest entrance followed by females flying 
from the area and males re-entering the nest. Such in situ mating is 
common in rare ant species apparently due to very low probability 
of reproductives finding individuals from other nests with which to 
mate (Wilson 1963). Following copulation and departure of P. colei 
females, male and female P. rugosus flew from the crater as the 
temperature continued to climb. Reproductive forms of P. rugosus 
fly to a site away from the nest and copulate there (Holldobler 
1976). Mating activities of host and inquiline were separated by at 
least 30 min and, perhaps more importantly, 3° C ground tempera- 
ture (Table 1). Reproductive forms of each species were seen 
occasionally in the nest entrance during the mating activity of the 
other. On at least one occasion, P. colei males tried unsuccessfully 
to mount a P. rugosus female. During this flight I observed no 
differences in behavior of host workers to host or inquiline repro- 
ductives. P. rugosus workers frequently encircled copulating pairs 
of P. colei and frantically ran around them, although they never 
interfered. 
During 1979 routine observations were begun at the study area on 
18 September. A complete P. colei flight was observed at the host 
nest during the afternoon of 30 September immediately following a 
