Zerene eurydice

Geographic Range

Zerene eurydice is found from northern-central California south to Baja California. (Milne and Milne, 1980; Struttmann, 2005)


This butterfly can be found in foothills, chaparral, and oak or coniferous woodlands. (Struttmann, 2005)

Physical Description

Dog faced butterfly eggs are ribbed, and flattened on one side. When first laid, eggs are pale green or yellow colored, turning crimson as they mature. Larvae are dull green and covered in small black points. They have a white lateral band, which is edged with red below and black dots above. There is also a pale band around each body segment. Larvae have 6 normal, jointed, muscular legs attached to the abdomen which each have a hook on the end used for grasping. There are also 10 false legs called prolegs attached to the abdominal segments, which are soft and fleshy.

Adult butterflies have enormous eyes, and their wings are covered in scales, which aid in flight aerodynamics and heat insulation. The last segments of their abdomens are fused, and almost all of their bodies are covered in tactile setae -hairs that sense vibrations and touch. Zerene eurydice forwings have a yellow to pinkish-orange "dogs head" enclosed by dark purplish brown-to-black along the front and outer margins of the wing. Females have entirely yellow forewings except for a black upper forewing cell spot. Both males and females have solid yellow hindwings. (Milne and Milne, 1980; Scott, 1986; Struttmann, 2005)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • Average wingspan
    5.1-6.3 cm


Zerene eurydice, like other butterflies, go through a complete metamorphosis before emerging from their pupa as an adult. After chewing their way out of the egg, larvae have voracious appetites. They eat and grow, and as they grow they must molt their old, tight exoskeleton and grow a new, larger one. Each period between molts is called an instar. Each larva must pass through several instars before it is ready to pupate and become an adult. When ready, the larva spins inself a cacoon made from silk, pupates inside of it, and emerges about one week later as an adult butterfly. (Milne and Milne, 1980; Scott, 1986)


Males search for receptive females to mate with. During copulation, the male first injects a sac called a spermatophore into the mating tube of the female. He then injects his sperm into the spermatophore, followed by a substance that later hardens into a clear plug. This plug is to prevent other males from mating with the same female, although after a few days the plug is broken down and absorbed by enzymes in the females body, and she may mate again. Mating takes longer in cool weather, or if the male mated previously in the day as it may take several hours for his body to recharge the nessesary copulatory chemicals. (Scott, 1986)

The male Zerene eurydice searches for females to mate with. After mating, the female lays eggs singly on leaves of the host plant, false indigo. The eggs are pale green or yellow-green and later turn crimson. (Scott, 1986)

  • Breeding season
    early spring and late summer
  • Average eggs per season

After the female lays her eggs, she does not provide any further care for offspring.

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female


Spring flight: 10-11 months br

Summer flight: 3.5-4 months br

(Struttmann, date unknown)


The California dogface butterfly is most common from April to May and July through August. Adults are fast fliers, and can probably fly for several kilometers. (Scott, 1986)

Food Habits

The primary food source of the California dogface butterfly is the plant Amorpha californica (false indigo). The caterpillar eats the leaves of Amorpha californica, and the adults drink flower nectar from plants of the mustard family. (Scott, 1986)

  • Plant Foods
  • leaves
  • nectar


In the egg, larva, and pupal stages, Zerene eurydice uses camouflage to avoid being eaten. Larvae are a greenish yellow color, the same color as the false indigo plan on which it feeds and lives on.

  • Known Predators
    • The California dogface, like most other butterflies, is prey to many species which include ants, spiders, wasps, parasitic wasps, parasitic flies, birds, rats, toads, lizards, praying mantis', and snakes.

Economic Importance for Humans: Positive

There is no known economic importance of this species.

Economic Importance for Humans: Negative

There is no known economic importance of this species.

Conservation Status

This species requires no special conservation status.

Other Comments

Zerene eurydice was adopted as California's state insect in 1972.

Zerene eurydice was originally placed in the genus Colias.

Butterflies breathe through a detailed network of tracheae, which are filled with air from tiny holes in the exoskeleton called spiracles. When muscles in the butterfly’s body move to either relax or contract, this causes some spiracles to shut and others to open creating a vacuum effect, sucking air through the tracheae. Circulation in the butterfly works much the same way, with hemolymph (insect blood) being pumped throughout the body by muscular contraction. (Milne and Milne, 1980; Scott, 1986)


Sara Diamond (author, editor), Animal Diversity Web.

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

Kijun Hong (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.



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

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.

delayed fertilization

a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage.

  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.


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


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


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.


This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.


an animal that mainly eats nectar from flowers


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season


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


mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.


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.


Milne, L., M. Milne. 1980. Field Guide to North American Insects and Spiders. New York: Alfred A. Knopf Inc..

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

Struttmann, J. 2005. "Northern Prairie Wildlife Research Center: Butterflies of North America" (On-line). Accessed Novermber 29, 2001 at http://www.npwrc.usgs.gov/resource/distr/lepid/bflyusa/ca/725.htm.