Ah, September. Such a lovely month in Canyon Country! Though the heat of summer may persist throughout the month, there are signs that the seasons are about to change. At higher elevations, aspens and Gambel’s oak leaves begin to change color from the verdant green of summer to yellow and golds of fall. Songbirds, waterfowl, raptors, and shorebirds wing their way through the region on their southbound migration. And down in the canyons and along the washes, abundant rabbitbrush shrubs continue to bloom beckoning pollinators such as bees and butterflies.

In Utah, over 250 species of butterflies have been recorded. Some are common and abundant, others are rare, as in endemic or globally imperiled, or rare as in observed outside of their normal range. According to Robb Hannawacker, NPS ranger and lepidopterist, some Sonoran Desert butterflies may be swept up and carried aloft by powerful winds during summer monsoons, only to drop out of the storms in the Canyon Country.

Others, such as the American snout butterfly with its long beak-like snout may appear, like they did in 2021 in the Needles District of Canyonlands National Park, during irruptions or irregular movements to feast on netleaf hackberry leaves.

During a September hike in Canyon Country, when many other wildflowers have gone to seed, rabbitbrush fills a key role in providing nectar for butterflies.

Rubber rabbitbrush (Ericameria nauseosa), a member of the Aster or Sunflower family, is a widely distributed shrub throughout the Intermountain West that is often overlooked due its unappealing interest to livestock. However, in late summer, these shrubs bloom in abundance and grace the landscape in swaths of yellow. The shrubs, with multiple grayish-green stems, attract wildlife for various reasons. Deer may feed on leaves and stems, often covered with a felt-like mat of dense hairs. Birds, such as the lesser goldfinch, will feed on maturing seeds. And bees and butterflies, are attracted to the rounded clusters of abundant yellowish, tubular flowers which cloak the plant and provide nectar rewards to these pollinators.

Painted ladies, one of the most widely distributed butterflies in North America, may be observed nectaring on rabbitbrush flowers or those of thistle, aster, and even milkweed. They are also common in backyard gardens feeding on nectar of ornamental plants. Though the southbound migration of these butterflies is a subject of debate, some populations overwinter in Mexico to replenish these northern populations sometimes during spectacular spring flights.

Anise and western swallowtails are large, yellow butterflies with black markings that occur in Canyon Country and in late summer may be seen “hill-topping,” a behavior where the males find a suitable location to perch and wait for females to breed. Developing caterpillars will overwinter in the chrysalid stage, awaiting the warmth of spring.

Monarch butterflies have a “stained glass pattern” with orange “panes” seemingly connected by “leaded” black veins. These classic butterflies rely on milkweed plants for nectaring and hosts for their caterpillars. Multiple generations move north and south, with the final adult phase overwintering in warmer climates such as California, Florida, and Mexico. These large, graceful butterflies may utilize rabbitbrush flowers, especially when the milkweeds have all gone to seed.

So, if you’re out on September hike and do spot some of these spectacular species, whether a common species like the western tiger swallowtail or a rare one such as the American snout butterfly, snap a photo and send it to the Facebook group “Lepidoptera of the Northern Colorado Plateau” that Robb manages, and share your excitement of September butterflies with others.