A close relative of the clouded sulphur with deeper orange-yellow color. Especially associated with alfalfa fields — sometimes called the "alfalfa butterfly."

Also called: Alfalfa Butterfly

Native status: Native to North America

§ Quick facts

SizeWingspan 4.4–7 cm (1.7–2.8 in)
Weight~0.3 g
LifespanAdults 2–4 weeks; multiple generations per year
OrderLepidoptera
FamilyPieridae

§ Encyclopedia

Colias eurytheme, the orange sulphur, also known as the alfalfa butterfly and in its larval stage as the alfalfa caterpillar, is a butterfly of the family Pieridae, where it belongs to the lowland group of "clouded yellows and sulphurs" subfamily Coliadinae. It is found throughout North America from southern Canada to Mexico.

Source: Wikipedia — Colias eurytheme Licensed under CC BY-SA 4.0

§ Identification

Field marks. Medium butterfly with deep orange ground color on upper wings, broad black borders; black "comma" mark on forewings; underside paler with small pink-edged spot on hindwing.

Similar species. Clouded Sulphur (less orange; more lemon-yellow). Cloudless Sulphur (much larger). Sleepy Orange (different markings).

Voice. N/A

§ Diet & behavior

Diet. Adults: nectar from many flowers. Caterpillars: alfalfa, clover, vetch, and other legumes.

Behavior. Among the most common butterflies in alfalfa-growing regions. Range expanded dramatically from the southern US during the 1900s as alfalfa cultivation spread northward. Sometimes called the "Alfalfa Butterfly" by farmers; female caterpillars (rare among Lepidoptera) defend against parasitoid wasps with chemical signals derived from alfalfa compounds. Hybridizes occasionally with Clouded Sulphur in zones of contact.

§ Range

Across most of North America

§ Habitat

Open habitats, alfalfa fields, meadows, gardens

§ Threats

Pesticide drift, alfalfa monoculture without flowers.

§ Conservation status

According to the IUCN Red List, the orange sulphur is currently classified as Least Concern.

§ What helps

Plant alfalfa and clover with native flowers. Skip pesticides. Maintain meadows.

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§ Further reading

§ Sources cited

  • Butterflies and Moths of North America
  • Xerces Society
  • iNaturalist