White-lined Sphinx Moths
The sphinx moth (family Sphingidae) is also called the hawk moth and the hummingbird moth because of its hovering, swift flight patterns. These stout-bodied moths have long, narrow forewings and shorter hindwings, with wingspans ranging from 2 to 8 inches. Many species pollinate flowers such as orchids, petunias and evening primroses while sucking their nectar with a proboscis (feeding tube) that exceeds 10 inches in some species.
Throughout all the North American desert regions.
Found in many diverse habitats and on many desert plants, especially after rains.
White-lined sphinx moths are among the largest flying insects of the deserts, with adult wingspans exceeding 5 inches. Larvae can be just as long, up to 5 inches, with most having a prominent horn at the rear of their fleshy body. When alarmed, these larvae rear up their heads in a threatening sphinx-like posture and may emit a thick, green substance from their mouths.
The body of the white-lined sphinx moth ranges in length from 2 1/2 to 3 1/2 inches. It has a prominent brown head, a brown thorax with 6 white stripes and a brown abdomen with paired dark spots on each segment. The forewings are brown with a buff-colored band from base to tip and veins outlined in white. The hind wings are pink, turning to dark brown near the margins.
Most people only see the larvae, commonly know as the white sphinx caterpillar or the hornworm. The caterpillars feed on desert wildflowers in the spring. They are eating machines and can wipe out whole fields of wildflowers. The Swainson's hawks feed on these same larvae as flocks migrate through the desert. Some years, millions of the larvae are feeding on the plants, and desert roads are covered with caterpillars crushed by cars.
Sphinx moth larvae migrate underground to metamorphose into adult moths, who then dig their way to the surface. Mating occurs shortly thereafter, with females laying as many as 1,000 eggs on the underside of food plants. Eggs hatch within a few days. In the Sonoran and Chihuahuan deserts, there may be two broods, one in the spring and another in summer. In the colder Great Basin desert, only one brood is produced. Males and females die after they have completed their roles in the reproductive process.
Sphinx moths emerge at dusk from their hiding places and begin feeding on the nectar of flowers. Their size, combined with their rapid wing beats, allows them to hover and feed in the manner of hummingbirds, for which they are sometimes mistaken.
This manner of flight requires a great deal of energy and creates a good deal of heat in the moth's body. For these reasons, moths feed exclusively on nectar and seek flowers which produce large amounts of this water source, and also contain high amounts of sugar. Such is the case with the evening primrose (Onagraceae) family, and particularly the dune evening primrose, which the white-lined sphinx moth is responsible for pollinating.
-- A.R. Royo
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