The Plant Clinic often received inquiries about large moths found. Here are some you may encounter in Oregon.

Polyphemus Moth

Antheraea polyphemus

Habitat: Commonly found in wet forests, woodlands, wetlands and orchards in the PNW. Also found in urbanized areas and suburban gardens.

Caterpillars: Caterpillars have large and bright green bodies and a duller brownish head. They have red coloration at the base of setae (bristles) along the body. Polyphemus moth caterpillars are feed on many broadleaf trees during the late spring, including white oak and big-leaf maple.

Adults: Adults are nocturnal and do not feed. Wingspan is 9.9–16.5 cm.

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Blinded Sphinx Moth

Paonias excaecatus

Habitat: Found in dry forests west of the Cascades Mountains and riparian forests east of the Cascades.

Caterpillars: Caterpillars are blue-green and green with little pale granules, faint yellow stripes and a posterior horn. They may have variable red or purple blotches along body. They feed on the leaves of trees and shrubs, especially oaks, hawthorn and ocean-spray, during July and August.

Adults: Adults are nocturnal and fly from late spring to midsummer. They do not feed. Wingspan is 6–8.5 cm.

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Ceanothus Silkmoth

Hyalophora euryalus

Habitat: Found in woodlands and in both wet and dry forests. Widely distributed throughout the PNW.

Caterpillars: Caterpillars are green with round yellow/orange and white tubercles. During July and August they are common on snowbrush and bitterbrush, and sometimes on Douglas fir.

Adults: Adults are nocturnal and fly in the spring. They do not feed. Wingspan is 7.4–12.7 cm.

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One-eyed Sphinx

Smerinthus cerisyi

Habitat: A common moth found widely in wet forests in Western NA, particularly in coastal forests, as well as riparian forests east of the Cascades.

Caterpillars: Caterpillars are green with pale granules, thin yellow diagonal lines, bolder yellow lateral stripes, and a caudal horn. They feed on foliage of willows and poplars.

Adults: Adults are nocturnal and do not feed. Wingspan is about 9.5 cm.

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Pandora Pinemoth

Coloradia pandora

Habitat: Found in dry coniferous forests, and are particularly abundant in ponderosa pine forests where it is considered a pest.

Caterpillars: Caterpillars have brown-black bodies with short black scoli (bristles) and light dashes. Caterpillars very common and feed on conifers (e.g. Ponderosa pine) during the late summer.

Adults: Adults fly in midsummer. Wingspan is 7.3–9.1 cm.

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Western Poplar Sphinx

Pachysphinx occidentalis

Habitat: Widely distributed in the PNW east of the Cascades, but mostly restricted to riparian habitats.

Caterpillars: Caterpillars have green bodies with light granules, white lateral stripes and a short caudal horn. They feed on the leaves of cottonwoods and willows.

Adults: Adults fly in the early summer. They are nocturnal and do not feed as adults. Wingspan is 13–15 cm.

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