Colias eurytheme

Geographic Range

Orange sulphurs historically were a western species in the Nearctic region, but moved eastward across North America during the late 1800’s due to logging and the planting of alfalfa fields. They now are found throughout North America to southern Mexico. (Iftner, et al., 1992; Scott, 1986)


This species can be found in most any open area, including vacant lots, pastures, open fields, roadsides, and clover and alfalfa fields. (Iftner, et al., 1992; Scott, 1986; Struttman, 2004)

Physical Description

The upper surface of the wings is primarily orange, although some females are white. The underside of the hindwing has a silver spot encircled by two red rings and a satellite spot. The upper surface of the males’ wings reflect ultraviolet, which is caused by a recessive gene on the X chromosome. Orange sulphurs are strongly polymorphic, and the general practice is if a sulphur has any orange on the wings at all it is called an orange sulphur. The average wing length of males is 2.4 cm, with a range of 2.1 - –2.8 cm. Average females wing length is 2.6 cm, with a range of 2.3 - –3.1 cm. (Opler and Krizek, 1984; Scott, 1986; Shapiro, 1966)

The cream colored eggs are spindle shaped and turn crimson with age. (Opler and Krizek, 1984)

The larvae are green with a white lateral band and faint green dorsal lines. (Scott, 1986)

  • Sexual Dimorphism
  • female larger
  • sexes colored or patterned differently
  • Range wingspan
    4.1 to 6.2 cm
    1.61 to 2.44 in


In laboratory experiments, orange sulphurs took 31 days to mature from eggs to adults. Scott (1984) reports that the third and fourth stage larvae hibernate, while Opler (1984) states that orange sulphurs overwinter as crysales’. (Opler and Krizek, 1984; Scott, 1986)


Males spend their days patrolling their territories daily seeking females. They recognize the females visually, focusing on the coloration of the underside of the hindwing. The males are repelled by ultraviolet reflection on other males’ wings. Females appear not to care about the coloration of the males but ultraviolet reflection must be present, which helps reduce hybridization with yellow sulphurs Colias philodice that lack the reflection. (Scott, 1986)

Female orange sulphurs begin to lay eggs when they have been adults for several days. In the lab they can lay up to 700 eggs. The eggs are laid singly in the middle of the upper surface of the host plant'’s leaf. (Opler and Krizek, 1984)

  • Breeding interval
    Orange sulphurs have several broods throughout the warm seasons.
  • Range eggs per season
    700 (high)

There is no parental care given by adult butterflies.

  • Parental Investment
  • no parental involvement


Captive adult females have been found to live up to 39 days. In Virginia during a mark-release-recapture study, wild adult females had a lifespan of 14 days, males 25. If they overwinter, their entire lifespan may be almost a year. (Opler and Krizek, 1984; Scott, 1986)

  • Range lifespan
    Status: captivity
    1 (high) years


Orange sulphurs roost in small groups at night, most often near the ground. (Opler and Krizek, 1984)

Communication and Perception

Orange sulphurs find potential mates using their vision. (Scott, 1986)

Food Habits

The hostplants are in the family Fabiacae. The main food plant of the caterpillars is alfalfa (Medicago sativa). (Iftner, et al., 1992; Scott, 1986)

Adults will sip from mud puddles and take nectar from a variety of plant species, including alfalfa, clovers (Trifolium), milkweeds (Asclepias), selfheal (Prunella vulgaris), teasel (Depsacus sylvestris), peppermint (Mentha piperita), horseweed (Erigeron canadensis), purple coneflower (Echinacae pupurea), sunflower (Helianthus hirsutus), asters (Aster), and goldenrods (Solidago). (Iftner, et al., 1992; Scott, 1986)

  • Plant Foods
  • leaves
  • nectar


Predators of all life stages of butterflies include a variety of insect parasatoids. These wasps or flies will consume the body fluids first, and then eat the internal organs, ultimately killing the butterfly. Those wasps that lay eggs inside the host body include species in many different groups: Ichneumonidae, Braconidae, Pteromalidae, Chalcidoidea, Encyrtidae, Eulophidae, Scelionidae, Trichogrammatidae, and others. Trichogrammatids live inside the eggs, and are smaller than a pinhead. Certain flies (Tachinidae, some Sarcophagidae, etc.) produce large eggs and glue them onto the outside of the host larva, where the hatching fly larvae then burrow into the butterfly larvae. Other flies will lays many small eggs directly on the larval hostplants, and these are ingested by the caterpillars as they feed. (Scott, 1986)

Most predators of butterflies are other insects. Praying mantis, lacewings, ladybird beetles, assasin bugs, carabid beetles, spiders, ants, and wasps (Vespidae, Pompilidae, and others) prey upon the larvae. Adult butterflies are eaten by robber flies, ambush bugs, spiders, dragonflies, ants, wasps (Vespidae and Sphecidae), and tiger beetles. The sundew plant is known to catch some butterflies. (Scott, 1986)

There are also many vertebrate predators including lizards, frogs, toads, birds, mice, and other rodents.

Ecosystem Roles

Orange sulphurs serve as minor pollinators and prey for many species of predators.

  • Ecosystem Impact
  • pollinates

Economic Importance for Humans: Positive

Orange sulphurs provide enjoyment of people interested in butterfly watching.

Economic Importance for Humans: Negative

Orange sulphur caterpillars can be serious pests on alfalfa crops. (Iftner, et al., 1992)

  • Negative Impacts
  • crop pest

Conservation Status

Orange sulphurs are stable rangewide.

Other Comments

Other common names include alfalfa suphur, alfalfa caterpillar, Eurytheme, Eurytheme sulphur, orange clover butterfly, roadside sulphur, and Boisduval’s sulphur. (Miller, 1992)


Matthew Wund (editor), University of Michigan-Ann Arbor.

Barb Barton (author), Special Contributors.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map


living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


a period of time when growth or development is suspended in insects and other invertebrates, it can usually only be ended the appropriate environmental stimulus.

  1. active during the day, 2. lasting for one day.

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature


union of egg and spermatozoan


an animal that mainly eats leaves.


An animal that eats mainly plants or parts of plants.


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

internal fertilization

fertilization takes place within the female's body


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.


having the capacity to move from one place to another.


an animal that mainly eats nectar from flowers


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.


Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season


reproduction that includes combining the genetic contribution of two individuals, a male and a female


living in residential areas on the outskirts of large cities or towns.


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


Living on the ground.


defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.


A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.


living in cities and large towns, landscapes dominated by human structures and activity.


uses sight to communicate


Iftner, D., J. Shuey, J. Calhoun. 1992. Butterflies and Skippers of Ohio. Columbus, OH: Ohio Biological Survey Bulletin, Vol 9 No. 1.

Miller, J. 1992. The Common Names of North American Butterflies. Washington, DC: Smithsonian Institute Press.

Opler, P., G. Krizek. 1984. Butterflies East of the Great Plains. Baltimore: John Hopkins University Press.

Scott, J. 1986. The Butterflies of North America. Stanford, CA: Stanford University Press.

Shapiro, A. 1966. Butterflies of the Delaware Valley. American Entomological Society Special Publication.

Struttman, J. 2004. "Butterflies of Texas; Orange Sulphur Colias eurytheme " (On-line). Butterflies of North America. Accessed November 22, 2004 at