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Common Buckeye

Junonia coenia

Common Buckeye

Adults Fly

July–October (often peaking August–September).

Eggs Laid

July–September (when adults are most common locally).

Larvae Active

July–October.

Overwintering

Does not reliably overwinter in the Willamette Valley due to freezing sensitivity; many individuals arrive via seasonal movement.

Conservation (NatureServe)

G5 (Secure)
Widespread; abundance in Oregon can vary year to year because many are migrants.

Caterpillar Host Plants (Willamette Valley natives)

  • Common monkeyflower (yellow seep monkeyflower) Erythranthe guttata — Native; thrives in seeps and wet edges—reported host genus (Mimulus/Erythranthe).
  • Woolly plantain Plantago patagonica — Native plantain of dry, open ground.
  • California plantain Plantago elongata — Native annual plantain of open, seasonally moist sites.

Favorite Nectar Flowers (Willamette Valley natives)

  • Douglas aster Symphyotrichum subspicatum
  • Canada goldenrod Solidago canadensis
  • Gumweed Grindelia integrifolia — Native composite; strong late-season nectar.
  • Common yarrow Achillea millefolium
  • Oregon sunshine Eriophyllum lanatum

What the Caterpillars Eat

Leaves of host plants in Plantaginaceae/Phrymaceae—locally, monkeyflowers (Erythranthe/Mimulus) and native plantains (Plantago) are good candidates.

The Common Buckeye looks like it was designed by a comic-book artist: rich brown wings with bold orange bars and four dramatic eyespots. In the Willamette Valley it’s most often noticed in late summer and early fall, especially in open, sunny places with low vegetation and a bit of bare ground.

Buckeyes love to perch—on trails, rocks, fence posts—then burst into flight and circle back to the same spot. Adults nectar on a wide range of flowers, especially composites like asters and goldenrods.

This butterfly is sensitive to freezing, so it typically doesn’t make it through colder winters here. In many years, what we see in Oregon represents seasonal movement from warmer regions, with breeding concentrated where host plants are abundant.

Fun Facts

  • Those big eyespots aren’t just for show—they can startle predators, and the butterfly will often flash them when disturbed.
  • Buckeyes commonly return to the same perch repeatedly, which makes them a fun species for close observation and photography.

Sources

Solitary wasp

A solitary wasp has no colony of workers helping raise her young. A female may stock her own nest cells with food, or find a host for her developing offspring. Solitary describes social life; parasitoid describes a feeding strategy. A wasp can be both.

Social wasp

Social wasps share a nest and cooperate in raising young. In yellowjacket and paper wasp colonies, reproductive females lay eggs and workers help feed the brood and maintain the nest. They can defend that nest, so observing a forager is different from approaching a colony.

Non-native Social wasp

This is a social wasp introduced beyond its natural range. In this case the European paper wasp was introduced to North America from Europe, probably hidden in shipping materials. Non-native describes its origin, while social describes colony life.