1967 ] Willey & Willey — Populations of Grasshoppers 
51 
21 to 29%. Then in a distance of only i 1 /^ miles across dense chap- 
arral the proportions drop to 6% orange (n=i87) at the head of 
East Portal Canyon (# 9). Late in the season of 1966, we sampled 
the area between these two localities and found only three openings 
in the chaparral ranging from about 5 to 10 acres each. The pro- 
portions were about 10% orange in each habitat (total 11=87, 
locality #8). Recently, trails six feet wide through the brush have 
been cleared to allow cattle access to the grass. Several Arphia were 
found on these trails between the meadows. Chaparral in this area 
is 6 to 8 ft tall and impenetrable to man. It is clearly a major factor 
in the isolation of A. conspersa demes. 
Continuing eastward along the South Rim (plate 7), the propor- 
tions of orange diminish gradually to zero on Fitzpatrick Mesa 
(#16). Then on the eastern portion of the mesa (#17), orange 
individuals appear in small numbers. The proportions rapidly in- 
crease eastward to Sapinero (#40), where the Black Canyon begins. 
This population was about 85% orange and showed the influence of 
a major orange- winged population continuous with the Elk Moun- 
tain centers north of the river. The presence of a large isolated 
yellow population in the Soap Creek Valley north of Sapinero and 
the Gunnison River illustrates the complexity of the geographic 
variation in the eastern populations. On Black Mesa a line of aspen- 
spruce forest 2 miles wide separates the eastern yellow outpost 
(locality #32, 28% orange, n=i26) from the north-western orange- 
winged populations (at #31, 100% orange, n=io8) as effectively 
as the Black Canyon does. 
Westward along the North Rim of the canyon, the orange popu- 
lations afford less obvious clinal variation than is true with the South 
Rim populations. The eastern demes near the zone of contact with 
the Soap Creek yellow, though counted by sight transect as all orange 
or with less than 1% yellow, include some lighter orange individuals 
— presumably heterozygotes. Collections show a complex phenotype 
series which so far has defied biometric analysis. Genetic analysis of 
each phenotype is now underway in laboratory matings. 
Turning to the canyon itself, only three areas seem to have suitable 
and continuous habitat down to the river on both sides to afford a 
crossing point. These points are, west to east, Red Rock Canyon and 
an unnamed canyon (#1) just west of it, East Portal (#10), and 
Blue Creek. West of Red Rock Canyon the southern population is 
uniformly orange (n=86) and may be the source of the orange 
