The ravine's galleries are painted autumn yellow, winter gray, spring green, and summer brown. Most tree and shrub leaves turn yellow, and the low-angle sunshine reflects yellow. Autumn broods of appropriately named sulphur butterflies are peaking now and will dominate an autumn butterfly fauna that includes some darker, overwintering, orange and brown, leaf-winged species. Cloudless sulphurs with three-inch wingspans are particularly striking, as they dance among the sun spots and falling leaves. Dainty, sleepy, and clouded sulphurs, and a late alfalfa, little, or dogface may join the party. Yellow flowers began with goldenrods in late August and continued with goldeneyes in October. Then white frostweed came along, followed by white asters. Actually, white is the dominant flower color of earliest spring and latest autumn, whereas yellow dominates in late summer and mid-autumn. Blue is third in annual frequency but chiefly a spring color, while red is scarce throughout the growing season. Current yellows attract sulphurs and bumblebees, by contrast to spring whites visited by brown and bluish butterflies, honeybees, and sphinx moths. Courtesy of these insect pollinators, flower colors rotate in the ravine's seasonal galleries.