U.S. Fish & Wildlife Service

Sacramento Fish & Wildlife OfficeServing the people, conserving the fish, wildlife, and plants of California

A Unit Of The Pacific Southwest Region

Kids' Species Information

Mission Blue Butterfly Stock

Mission Blue Butterfly

Mission Blue Butterfly

Photo: David Wright, USFWS


Endangered. This means the species is in danger of dying out. We are working to prevent this.


The mission blue is a small, delicate butterfly. Wingspread is about 2.5 to 3.6 centimeters. (1 to 1.5 inch)

Males and females have very different wings. The tops of males' wings are iridescent blue and lavender. Females' wings are dark brown with blue at the base.

In both males and females, wing edges are black. They have fringes made of long white hair-like scales. The undersides of the wings are whitish with small gray and larger black circles.


Adults drink flower nectar from buckwheat, golden asters, wild hyacinths and other plants. Caterpillars eat only lupine.


Coastal chaparral and grasslands. See photo.


San Bruno Mountain

Photo: USFWS

You probably know that caterpillars turn into butterflies. Here is how it happens in mission blue butterflies.

Adults can be seen flying around from about late March to early July. Each of them only lives about a week.

Females lay eggs on lupine plants. (A great place to look for pictures of plants is CalPhotos. Search for silver lupine, summer lupine or manycolored lupine.)

The eggs hatch into caterpillars in 4-7 days. These feed on the lupine. Then they crawl into the leaves at the base of the plant.

When a caterpillar crawls into leaves, it becomes a pupa. Pupae are very different from butterflies and caterpillars. If you saw a pupa, you would think it was part of a plant.

In the spring, the butterflies-to-be become caterpillars again. They are tended by ants. The caterpillars give off a sweet liquid called "honeydew" that attracts the ants. The ants protect the caterpillars from predators.


Wasps, other insects and rodents may prey on pupae. We are not sure.


A small colony is located on Twin Peaks in San Francisco. Some live at the Golden Gate National Recreation Area in the Marin Headlands.

Most of the mission blues live on San Bruno Mountain. The 3,600-acre mountain in northern San Mateo County has most of the remaining habitat for three endangered species. These are the mission blue, callippe silverspot and San Bruno elfin.


These include housing developments, non-native plants and excessive recreational use. See California Academy of Sciences Hotspot page about this species.


Do you live near the San Francisco Bay? You may be able to help restore the mission blue's home. Search the Internet for mission blue butterfly volunteer. People are needed to pull weeds and plant native plants.


If you live in the San Francisco Bay area, you may see a mission blue. Wherever you live, you can watch butterflies.

Talk to your parents about planting a butterfly garden. There are lots of web pages about this. Here is a good one.


A good field guide to common butterflies is Peterson First Guide to Butterflies and Moths by Paul A. Opler. Houghton Mifflin, 1998.

The same series includes Peterson First Guide to Caterpillars by Amy Bartlett Wright and Peterson First Guide to Insects of North America by Christopher Leahy. The latter book will teach you how biologists classify species.

Read about how the Golden Gate National Recreation Area improved mission blue habitat.

Make a butterfly garden. See Gardening for Butterflies, Audubon Magazine.

We are partners of the Butterfly Conservation Initiative.

Don't be put of by the name of the Children's Butterfly Site. It has lots of good stuff.

Life on the edge: a guide to California's endangered natural resources, edited by Carl Thelander, has information about lots of species. It is published by BioSystem Books. See the mission blue species account on pages 430-31.

Visit the online Essig Museum of Entomology - California's Endangered Insects.

Visit the U.S. Fish & Wildlife Service's Homework Help page to learn more about endangered species.

Words to Learn

Scientists who study insects are called entomologists.

Entomologists call blue butterflies Icaricia icarioides. Scientific names are in Latin or Greek.

The mission blue is a subspecies. Entomologists add missionensis for "mission" to the species name. So the full name of this subspecies is Icaricia icarioides missionensis.

Mission blues are in the Lycaenidae (gossamer-winged) family. This family is found on every continent except Antarctica.

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Last updated: November 29, 2017