The white-lined sphinx moth, Hyles lineata, is a common hawk moth in the family Sphingidae. This family includes several breathtakingly large moths often mistaken at first glance as a hummingbird because of its ability to hover while feeding with its extended proboscis. They are very fast, and the rapid beating of their wings creates a humming sound that is audible to humans. One giveaway that the organism is an insect would be a pair of antennae on top of the head.
The abundance and diversity of sphinx moths in Nebraska vary from year to year, but many have been recorded in our area. In 2021 there was an overwhelming number of sightings of white-lined sphinx moths. They have a broad geographical range and are frequently observed in large aggregations in the wild. People reported caterpillars in raised beds, vegetable and flower gardens, compost piles, and in the weeds growing from the cracks in the pavement.
Adult moths were spotted nectaring on blooms during the day and night, and people inadvertently dug up cocoons while weeding or late-season planting. There are normally two generations of white-lined sphinx moths per year with the first moths flying in Nebraska in May and the second generation flying in August and September.
Curious caterpillars
The eggs of the white-lined sphinx moth are laid on host plants so young caterpillars have a food source upon emergence. Caterpillars are highly variable in color, but the Midwest morph has a green body with orange or yellow markings and black specks. There is a yellow-orange horn at the end of its abdomen, sometimes with a black tip. This horntail is sometimes confused for a stinger; however, sphinx moth caterpillars are not stinging insects. They possess no venom, and are harmless to humans. Some caterpillars have black lines running lengthwise down the back, while others have a dark coloring throughout. Caterpillars of the same species in western locations may be a bright yellow instead of green. Mature caterpillars in July and August can be up to 3 ½” long.
Host plants for caterpillars
Spotted spurge (Euphorbia maculata) is an annual, which is often considered a weed in agricultural field crops, vegetable gardens, ornamental flower beds, and container plants. Spurge is a diverse group of plants in the family Euphoribaceae. It produces unusual floral structures, and contains a poisonous milky white latex-like sap. This sap can be a skin or eye irritant and may be toxic to some animals. Spotted spurge can be distinguished from other species by the red color on each leaf which occurs on down the center vein. It grows low to the ground and forms dense mats. It has dark green leaves that grow in opposite pairs. It also has hairy tiny pink flowers, fruit, stems, and leaves. It has a taproot deep into the soil.
Four o’clock (Mirabilis jalapa) is a hardy annual in the family Nyctaginaceae that blooms late in the day. Plants can spread outward and have multiple branches, resembling a shrub of 2-3 feet tall and wide. The stems are weak and brittle, and plants tend to flop over. Flowers are bright and pastel shades of white, yellow, pink, magenta, and red. Flowers of different colors (bicolored, speckled, or variated) can be found on the same plant, either simultaneously or at different times. They bloom in the summer through fall and are trumpet shaped flowers. Four o’clocks are pollinated by sphinx moths and attract nocturnal pollinators with long tongues. During the day they attract butterflies, moths, and hummingbirds. This plant is good for all soil types in full sun locations.
Evening primrose (Oenothera biennis) is an upright biennial in the family Onagraceae. An herbaceous forb, it commonly grows in fields, prairies, disturbed sites, and along roadsides and right-of-ways. Flowers have four yellow or gold petals that bloom in the summer, opening at dusk and closing in the morning. Flowers are fertilized by night-flying moths attracted to the mild lemon flower fragrance and bees in the early morning before the flowers close. Evening primrose is drought tolerant, and birds are attracted to the seeds.
Large pupae in the soil
Mature caterpillars burrow into soil 1 to 4” deep and go into pupal stage where they remain for 2-3 weeks before they emerge (eclose) as adult moths. There are two generations a year and the last generation will overwinter as pupae in the soil.
Adult sphinx moths
Male and female moths look similar with narrow-wings and a heavy body. The striped forewings have wing veins outlined in white scales. The wingspan is 2 ½” to 3 ½” long. Their species name lineata is Latin for “line” which refers to these white lines. The hindwing is bright pink with a dark brown-black band. Adults feed on nectar and can be seen mostly at dusk, but also in the day and night feeding.
Flowers for nectaring moths
White-lined sphinx moths prefer flowers that butterflies commonly feed on such as columbine, larkspur, petunia, honeysuckle, coneflower, lilac, butterfly weed, aster, and phlox. Plant flowers with continuous blooms throughout the season and with multiple florets with abundant nectar. Note: Avoid double flowers because they lack the nectar they need. During the day they prefer red and bright colored flowers, while later in the day, sphinx moths prefer white or pale tubular flowers that are easy to see in the evening, like evening primrose, angel’s trumpet, and moonflower.
Other daytime feeding sphinx moths:
Resources:
Dankert, N., S. Spomer, and J. Nikkila. Nebraska Lepidoptera: A Comprehensive Guide to Nebraska’s Butterflies & Moths. (website)
Francois, C. L. and G. Davidowitz. 2020. Genetic color polymorphism of the white-lined sphinx moth larva (Lepidoptera: Sphingidae). J. Indect Sci. 20(4):19.
Messenger, C. (1997). The Sphinx Moths (Lepidoptera: Sphingidae) of Nebraska. UNL Digital Commons.
Xerces Society. 2016. Gardening for Butterflies: How You Can Attract and Protect Beautiful, Beneficial Insects. Timber Press. (pp234-237).
All photos taken by me, Jody Green, on my iPhone. If you would like to use them for educational purposes, please email me for the original image.
Fantastic photos!