Smerinthus jamaicensis

The Twin-spotted Sphinx can be distinguished from other Smerinthus species by the two prominent eyespots on the hindwings (hence the common name). The similar One-eyed Sphinx (Smerinthus cerisyi) has only one eyespot per hindwing. The eyespots are revealed when the moth is disturbed, serving as a startle display against predators. At rest, the forewings fold over the hindwings, concealing the eyespots and rendering the moth nearly invisible against tree bark.

A medium-sized sphinx moth with the robust, streamlined body typical of the family. Forewings are cryptically patterned in shades of brown and gray, providing camouflage against bark. Hindwings display distinctive coloration with two prominent dark blue or black eyespots, each ringed with yellow or orange, which are revealed when the wings are spread. The abdomen tapers to a point. Wingspan ranges from approximately 50–70 mm.

Occurs in diverse habitats including deciduous and mixed woodlands, forest edges, suburban areas, and riparian corridors. Larval host plants determine local distribution. Adults are frequently attracted to artificial lights.

Widely distributed across North America from the Yukon Territory south through Canada and the United States. Present throughout most of the continental United States except absent from the southern half of western California. Records from Alberta, Manitoba, and Saskatchewan in Canada, and from Vermont in the northeastern United States.

Adults fly primarily from late spring through summer, with peak activity varying by latitude. In northern portions of the range, flight period is concentrated in June and July; more southerly populations may have extended flight periods or multiple generations.

Larvae feed on leaves of various woody plants including willow (Salix), poplar (Populus), and birch (Betula). Adults do not feed; they rely on fat reserves accumulated during the larval stage.

• Salix - larval host plant
• Populus - larval host plant
• Betula - larval host plant

Complete metamorphosis with four stages: egg, larva, pupa, and adult. Females lay eggs on host plant leaves. Larvae are green with diagonal white stripes and a horn at the posterior end, typical of sphinx moth caterpillars. Pupation occurs in a subterranean cell. Overwintering stage is the pupa. Adults emerge in spring to early summer.

Adults are nocturnal and strongly attracted to artificial light sources. When disturbed, they display the hindwing eyespots by spreading their wings, a defensive behavior thought to startle predators. Adults are capable of rapid, agile flight. Females have been observed laying eggs on illuminated sheets near light traps.

Larvae function as herbivores, consuming leaves of host trees and contributing to nutrient cycling. Adults serve as prey for nocturnal predators including bats and birds. The eyespot display suggests significant predation pressure driving the evolution of this anti-predator adaptation.

Occasionally encountered by the public at porch lights. Of minor economic importance; larvae may defoliate ornamental willows, poplars, or birches but rarely reach outbreak densities. Subject of interest among lepidopterists and moth enthusiasts, including during National Moth Week events.

• Smerinthus cerisyiSimilar size and coloration, but has one eyespot per hindwing rather than two; ranges overlap broadly
• Smerinthus ophthalmicaWestern species with similar appearance; allopatric or parapatric distribution reduces confusion

• Sphingidae
• moth
• North America
• sphinx moth
• nocturnal
• eyespots

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Bug Eric: Wasp Wednesday: Ammophila procera
• Bug Eric: National Moth Week Recap, 2015
• Heliconiidae | Beetles In The Bush