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Wildlife Gardening
Creating a Wildscape
"Our backyards can be a treasure trove of nature’s beauty and Colorado Wildscapes shows how to create an environment that encourages wildlife to visit. For me, being able to sit in my backyard and sketch all of the visitors that buzz, flutter and fly by is delightful indeed!" (Susie Mottashed, Illustrator)
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Oenothera howardii
Photo by: plants.USDA.gov
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Sphinx Moths & Evening-Primroses
by Stephen Jones, Boulder County Audubon Society, co-author of the Peterson Field Guide to the North American Prairie and Colorado Nature Almanac.
On warm summer evenings, I sometimes grab a favorite beverage and place a garden chair near our sprawling Organ Mountains Evening-Primrose (Oenothera organensis). The show begins around sunset, when the plant's 100 (or more) tight green flower bundles begin their magical transformation into cup-sized, lemon-yellow blossoms.
Some of the flowers take less than a minute to retract their long green bracts and unfurl. I feel the living, breathing energy of this night-blooming plant as the flower buds snap open and the crinkly petals stretch out, beckoning to potential pollinators.
Often as not, the pollinator is a White-lined Sphinx Moth. This "hummingbird moth" has a super-long proboscis (up to 10 inches!) that probes deep into the throat of the trumpet-shaped flowers and extracts sweet nectar. While nectaring, the moth rubs against the powdery yellow stamens, and the pollen sticks to its face. When the moth flies to another blossom, the pollen rubs off on the stigma and works its way down to the ovary.
White-lined Sphinx Moths are common throughout Colorado. They lay their eggs on evening-primroses, grapes, four o’clocks, and many other flowers. Their large green and yellow caterpillars pupate in burrows in the ground. Though most active at night, the adults also fly by day.
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White-lined Sphinx Moth
Photo by Dave Sutherland
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The White-lined Sphinx is one of three-dozen sphinx moths found in Colorado. Two other Colorado species, the Five-Spotted Hawkmoth and Carolina Sphinx, are decidedly less popular with gardeners. Their voracious larvae, the Tomato and Tobacco Hornworms, can defoliate garden plants in a hurry. However, these moths do not lay their eggs on evening-primroses, so adding these to your garden will not encourage them.
Any evening-primrose with conspicuous flowers will attract White-lined Sphinx Moths, bumblebees, and an occasional butterfly or hummingbird. Although my Organ Mountains Evening-Primrose is amazingly prolific, it's also very weedy and not native to our state. The Colorado Native Plant Society recommends the White Evening-Primrose (O. caespitosa) and Yellow Stemless Evening-Primrose (O. howardii) for our gardens. These showy natives thrive in a variety of soils and require little or no watering.
Harlequin's Gardens in Boulder carries an assortment of Colorado native evening-primroses, as does Rocky Mountain Native Plant Company in Rifle. You can order seeds online from The Prairie Nursery.
A word of caution: Flea beetles can invade evening-primroses and inflict serious damage. Mikl Brawner of Boulder's Harlequin's Gardens suggests spraying with an organic repellent, such as Neem, to keep these little metallic-green beetles at bay.
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