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Gray Hairstreak

Strymon melinus

Gray Hairstreak

Adults Fly

April–October (sometimes into early November in warm years).

Eggs Laid

April–September (often multiple broods; timing depends on spring warmth).

Larvae Active

May–October.

Overwintering

Overwinters mainly as a pupa (chrysalis) in sheltered spots (leaf litter, bark crevices, tucked vegetation).

Conservation (NatureServe)

G5 (Secure)
Widespread with many occurrences; still benefits from diverse native plant habitat.

Caterpillar Host Plants (Willamette Valley natives)

  • Bigleaf lupine Lupinus polyphyllus — Legume; a native lupine in the valley and foothills.
  • American vetch Vicia americana — Legume; common along edges and open woods.
  • Nevada pea Lathyrus nevadensis — Legume; woodland/edge pea native to western Oregon.
  • Meadow checkermallow Sidalcea campestris — Mallow family; a Willamette Valley native with showy pink blooms.
  • Nootka rose Rosa nutkana — Sometimes used by hairstreaks; also excellent structure for habitat.

Favorite Nectar Flowers (Willamette Valley natives)

  • Douglas aster Symphyotrichum subspicatum — Late-season nectar; a top native for butterflies.
  • Oregon sunshine Eriophyllum lanatum — Summer nectar; thrives in sunny, drier sites.
  • Common yarrow Achillea millefolium — Long bloom; great landing platform for small butterflies.
  • Pearly everlasting Anaphalis margaritacea — Dry-site native with long-lasting blooms.
  • Showy milkweed Asclepias speciosa — Strong nectar draw in mid-summer.

What the Caterpillars Eat

Primarily flowers and leaves of host plants—especially native legumes (lupines, vetches, peas) and mallows (checkermallow).

The Gray Hairstreak is one of those butterflies you start noticing everywhere once you learn its look: soft gray wings, a thin white line, and a pair of tiny tails on each hindwing. In sunny yards, parks, and weedy edges around Eugene, it’s a frequent visitor that never seems in a hurry—until it suddenly zips off like a wind-up toy.

What makes this species especially successful is flexibility. The caterpillars can use a wide range of host plants (especially native legumes and mallows), which helps the Gray Hairstreak show up in all kinds of habitats—from restored meadows to backyard borders.

Adults nectar on many small, flat-topped flowers, and you’ll also see them ‘puddling’ on damp soil for minerals. If you’re planting for them, aim for a long bloom season and a few native legumes tucked into the mix.

Fun Facts

  • The tails and orange spot create a ‘false head’—predators often strike the wrong end, letting the butterfly escape.
  • Many hairstreak caterpillars have relationships with ants; the ants may ‘tend’ them in exchange for sugary secretions.

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.