54 
Psyche 
[March 
of altitude on the phenology of populations within the canyon is of 
interest. For example, at the head of East Portal Canyon and nearby 
Coffee Pot Hill (elevation 8600 ft), on June 15, 1966, the insects 
were at their reproductive peak with high population density, nu- 
merous pairs in copula and constant spontaneous flights. Within the 
canyon at East Portal (elevation 6500 to 6700 ft) on June 19, 1966, 
the population was nearly non-existent. The males which were 
observed seldom flew and several which were captured had worn 
wings and missing legs. The climatological conditions were essentially 
identical and were optimal for behavioral interaction. On July 21, 
1965, the previous year, the population at the head of East Portal 
Canyon was clearly senescent, whereas no Arphia could be found 
below at East Portal. Indeed Trim erotro pis sparsa , a summer- 
brooded oedipodine, was at its peak. 
Conclusions 
It is doubtful that significant gene flow in Arphia conspersa occurs 
across the Black Canyon except at the three isolated points mentioned 
and these may be quite minimal. If it did, we would have to explain 
why the North Rim population is so free of the yellow phenotype 
and the eastern South Rim is so nearly free of the orange phenotype. 
We should expect the recorded SW winds to carry a winged species 
across the relatively short aerial distance between the two rims with 
a resulting admixture of the yellow phenotype in the now completely 
orange- winged populations of the North Rim. But examination of 
the data shows that this has not happened to any significant degree. 
Besides, the behavior of this species is not conducive to transport by 
wind, since increased velocity of wind suppresses flight activity. As 
we have seen, persistent chasing can force an Arphia across the road 
or over a hedge or down a gulch, but such pursuit is an artificial 
situation which seldom occurs in nature. Nearly constant canyon 
updrafts definitely prevent flying out over the cliff edges and flocks 
of swallows are active during the day at the rim edge, affording 
another efficient barrier to transcanyon gene flow. 
There is no obvious indication that habitats of the two rims differ. 
Fig. 2. (opposite page). Protocol of Arphia conspersa populations and 
locality elevations. 
3 Elevations are estimated from the following 7 1/2 minute U.S. Geo- 
logic Survey topographic maps: Black Ridge, Red Rock Canyon, Mt. 
Gunnison, Cathedral Peak, Curecanti Needle, Grizzly Ridge, X Lazy F 
Ranch, Sapinero, and Little Soap Park. 
This is the true Blue Mesa Summit east of Blue Creek on U.S. High- 
way 50. 
5 Several dilute orange and pink-winged specimens were observed or 
captured, although no yellow-winged individuals were recorded. 
