Syssphinx raspa

Syssphinx raspa can be distinguished from the very similar Syssphinx hubbardi and Syssphinx montana primarily by geographic distribution and subtle differences in genitalia. In areas where ranges overlap, dissection or DNA analysis may be required for definitive identification. Caterpillars of S. raspa and S. hubbardi are nearly identical in appearance and cannot be reliably separated in the field. The bright pink hindwings exposed when startled are characteristic of the genus Syssphinx and help distinguish these moths from other small saturniids.

Arid and semi-arid regions including desert scrub, mesquite-acacia woodlands, and riparian corridors. Associated with host plants in the genera Prosopis, Vachellia/Senegalia, and Cercidium. Occurs from low elevations to lower mountain slopes.

Middle America (Mexico) and southern North America. In the United States, occurs from central Texas west through southern New Mexico and Arizona to southern California. Extends south through Mexico to Veracruz.

Adults are on the wing primarily between June and September, with peak activity in July and August. In Texas, some populations may have multiple generations with adults appearing as late as November. One generation per year throughout most of the range.

Larvae feed on leaves of leguminous trees and shrubs including Catclaw Acacia (Senegalia greggii), Honey Mesquite (Prosopis glandulosa), and Little-leaf Palo Verde (Parkinsonia microphylla). In captivity, caterpillars have been reared successfully on Honey Locust (Gleditsia triacanthos), Black Locust (Robinia pseudoacacia), and Jerusalem Thorn (Parkinsonia aculeata). Adults do not feed.

• Senegalia greggii - larval hostCatclaw Acacia
• Prosopis glandulosa - larval hostHoney Mesquite
• Parkinsonia microphylla - larval hostLittle-leaf Palo Verde; formerly Cercidium microphyllum

Eggs are laid on host plant foliage. Young caterpillars feed individually on the undersides of leaf petioles, consuming leaf bases. Older larvae cut petioles and bend leaves downward to access more foliage, feeding primarily at night. Development from egg to pupa can occur in under three weeks for some individuals, though others from the same egg batch develop more slowly. Mature larvae descend to the ground and pupate underground in a shallow cell. Adults emerge in early evening and seek mates between 11 PM and 2 AM. Overwinters as pupa.

Adults are nocturnal and attracted to lights, including in urban areas. Males are more frequently attracted to lights than females. Larvae feed actively at night and can be located with a flashlight. When startled, adults expose the bright pink hindwings, presumably as a startle defense against predators.

Larval herbivore on native leguminous trees and shrubs. Adults serve as prey for nocturnal predators including bats and owls. Likely pollinator of night-blooming flowers, though this has not been documented. The underground pupal stage may serve as food for subterranean predators.

Occasionally reared by silkmoth enthusiasts. Not considered an agricultural or forestry pest. Adults may be encountered at porch lights in suburban and urban areas within its range. The species contributes to the biodiversity of desert ecosystems popular with ecotourists.

• Syssphinx hubbardiNearly identical in appearance and biology; distinguished primarily by subtle morphological differences and geographic range, with S. hubbardi more common in Arizona and S. raspa more widespread in Texas and Mexico. Caterpillars cannot be reliably separated in the field.
• Syssphinx montanaLarvae nearly identical to S. raspa and S. hubbardi; adults distinguished by genitalia and subtle wing pattern differences. Ranges may overlap in some areas.

• silkmoth
• Saturniidae
• desert moth
• nocturnal
• legume feeder

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Bug Eric: Moth Monday: Hubbard's Silkmoth
• Belostomatidae | Beetles In The Bush