Did You Know? 21 Incredible Mission Blue Butterfly Facts

Here are some cool Mission blue butterfly facts about the vibrant and Endangered butterfly found in San Francisco, California.

The Mission blue butterfly (scientifically know as Icaricia icarioides missionensis) is a subspecies of lycaenid butterflies native to the San Francisco Bay Area of the United States. This small, delicate, and vibrantly blue butterfly species was discovered in Twin Peaks in 1937. It was declared Endangered by this US federal government a few decades later after their population dropped significantly from developments on their grassland habitats and critical native plants. Today, there are limited populations in Marin County, San Mateo County, and San Francisco County.

If you like this article, check out our articles on the monarch butterfly and the morpho butterfly too.

Mission Blue Butterfly

Fact File

What do they prey on?


What do they eat?


Average litter size?


How much do they weigh?

0.01 oz (0.3 g)

How long are they?

0.83–1.3 in (21-33 mm) (wingspan)

How tall are they?


What do they look like?


Skin Type


What are their main threats?


What is their conservation status?


Where you'll find them

Coastal scrub and grasslands


San Francisco Bay, California





Scientific Name

Icaricia icarioides missionensis





Mission Blue Butterfly Interesting Facts

What type of animal is a Mission blue butterfly?

The Mission blue butterfly, Icaricia icarioides missionensis, is a butterfly.

What class of animal does a Mission blue butterfly belong to?

This butterfly subspecies belongs to the class Insecta (or insects) that are unique for their external skeleton (exoskeleton), a three-part body, compound eyes, three pairs of jointed legs, and one pair of antennae. It is also of the species Boisduval's blue (Icaricia icarioides) of the family Lycaenidae found in North America, which includes 25 recognized subspecies including the Mission blue butterfly.

How many Mission blue butterflies are there in the world?

According to the Golden Gate National Parks Conservancy, there are estimated populations of at least 20,000 butterflies in the San Francisco Bay area. The largest population can be found in a range of sites in San Mateo County, where there are over 18,000 Mission blue butterflies in San Bruno Mountain and over 2,000 at the Skyline Ridges. Up to 500 Mission blues can be found at Twin Peaks in San Franciso county.

Where does a Mission blue butterfly live?

This Boiduval’s blue butterfly subspecies was native to the coastal grasslands of the San Franciso Bay area. However, much of its original habitat has since been lost to urban development, so Mission blue butterflies have a limited population in certain areas including the Golden Gate National Recreation Area, Twin Peaks, and San Bruno Mountain.

What is a Mission blue butterfly's habitat?

The ideal Mission blue's habitat is grasslands and coastal scrub with at least one species of lupine: the silver lupine, the summer lupine, and the varied lupine. This beautiful host plant stems flowers and is critical for the survival of this Endangered species, as they require them for reproduction. The ideal Mission blue habitat is wherever these host plants are stable and thriving as this will ensure a stable Mission blue population.

Who do Mission blue butterflies live with?

These adult butterflies like most butterflies species tend to be solitary and any social behavior is rare.

How long does a Mission blue butterfly live?

Although the complete life cycle of Mission blue lasts one year, an adult will live for approximately one week. It is during this week that the female will lay its eggs on the host plant.

How do they reproduce?

In late March, female adults will fly around and lay eggs on their host plants found in their grassland habitat. Females lay one egg on the upper side leaf of a lupine species. Within 6-10 days, the eggs hatch, with the first and second instar larvae feeding on the mesophyll of the host plant. These extremely small caterpillars will feed for a short time, crawling to the plant base once they are ready to enter diapause, a dormant state. This usually takes place in late winter or the following spring, occurring three weeks after eclosion, and around the same time lupine plants (host) will shift their energy from leaf maintenance and begin its process of flower and seed production. Larvae will be in diapause for an extended period, for the rest of summer, through winter, and emerge into feeding in spring. Pupation lasts for around a week, with adult flight commencing again in March through to June, continuing the life cycle which takes one year.

What is their conservation status?

These butterflies are an Endangered species. Following the loss of their native grassland habitat, they were added to the Federal Endangered Species List in 1976.

Mission Blue Butterfly Fun Facts

What do Mission blue butterflies look like?

These butterflies are small and delicate, with differing wings for females and males. The tops of male wings are iridescent blue, while a female mission has dark brown wings with blue at the base.  Both sexes have black edges on their wings, with long white hair-like fringes. The undersides of the wings have small gray and larger black circles.

There are lots of cool facts about the Mission blue butterfly, Icaricia icarioides missionensis, a vibrant and Endangered butterfly found in limited populations throughout San Francisco, California. The female mission blue has dark brown wings that have a blue base.

How cute are they?

These butterflies are very cute, as they are extremely delicate,  lightweight, and very erratic in their flight movements.  If you're lucky to see one up close, their array of intricate unique textures and color mixes of differing blues and browns make them fascinating to look at.

How do they communicate?

Like other butterflies, Mission blues communicate primarily through chemical cues. Males will produce chemicals called pheromones to seduce females.

How big is a Mission blue butterfly?

This butterfly has an average wingspan of 0.83–1.3 in (21-33 mm). The Queen Alexandra’s birdwing, the largest type of butterfly, is 10 times the size of a mission blue with a wingspan of almost 10 in (25.4 cm).

How fast can a Mission blue butterfly fly?

The flight pattern of this butterfly is very fast and erratic.

How much does a Mission blue butterfly weigh?

Although the exact weight of an adult Mission blue is difficult to find, based on its average wingspan and comparison to other butterflies, it can be estimated that it weighs around 0.01 oz (0.3 g). For example, the smallest subspecies of butterflies, the western pygmy blue butterflies, have a wingspan of about 0.5 in (1.2 cm) and weigh as little as a few thousandths of a gram.

What are the male and female names of the species?

The names for males and females are simply female and male Mission blue butterfly.

What would you call a baby Mission blue butterfly?

Like all butterflies, the Mission blue will go through the life cycle of metamorphosis. As such, a baby Mission blue butterfly is called tiny larvae, caterpillar, larva, pupa, or chrysalis.

What do they eat?

Adults use their long proboscis to drink the flower nectar of buckwheat, golden asters, wild hyacinths, and other plants. Whilst mission blue larvae and caterpillars only eat lupines (their host plant) which includes the silver lupine, the summer lupine, and the varied lupine. These butterflies and their pupae are at risk of predators such as wasps and rodents such as rats and mice.

Are they poisonous?

These butterflies are extremely small and delicate and are definitely not poisonous.

Would they make a good pet?

All butterflies, including Mission blues, are fascinating creatures, and when kept as pets as you will witness the complete and fascinating metamorphosis. This includes the eggs, tiny larvae, caterpillars, chrysalis, and eventually beautiful adults.

Did you know...

The larvae are extremely small and rarely seen and only one generation occurs per year. Although federally this butterfly is considered Endangered, there is no provision for insects in the state's Endangered species legislation, the California Endangered Species Act. Therefore, it is not protected by state statutes in California.

How did Mission blue butterflies get their name?

The original population of these butterflies was discovered in the Mission District of San Francisco in 1937. It is for this reason they were called the Mission blue butterfly. However, this location is actually Twin Peaks in San Francisco County, which is no longer part of the Mission.

What does a blue butterfly symbolize?

Butterflies represent many things in different cultures. Generally, blue butterflies are positive symbols of life, rebirth, love, joy, and good fortune.

Why is the Mission blue butterfly important?

This butterfly is important because it is currently listed as an Endangered species and has been since 1976. Habitat loss, from both a range of private and public infrastructure developments, remains a significant threat to their declining butterfly populations. This habitat loss is critical because of their critical reliance on lupine host plants for reproduction. The abundance of the lupine plant species has significantly declined from these developments. The stable growth of lupines (the varied lupine, silver lupine, and the summer lupine) is critical to the longevity of this butterfly species.  Other negative human impacts include cultivation, grazing, and the introduction of invasive non-native exotic species such as pampas grass and the European gorse.

There are many ways you can support conservation and habitat restoration projects to help protect these butterflies. The U.S. Fish and Wildlife Service has implemented several restoration projects for legacy Mission blue sites, alongside Golden Gate National Parks Conservancy. In 1984, the Fish and Wildlife Service established a recovery plan to repair the Mission blues habitat damage of urban development. The Golden Gate National Parks Conservancy has followed the fish and wildlife recovery plan and commenced a range of habitat restoration projects. Restoration sites include Wolfback Ridge, Milagra Ridge, Hawk Hill, and Oakwood Valley. This project focuses on translocating adults from abundant regions like Marin County, to scarce areas. These projects commenced in 2017, with the successful translocation of a population from San Bruno Mountain in San Mateo County to the Milagra Ridge also in San Mateo County.

Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! For more relatable content, check out these purple emperor butterfly facts and viceroy butterfly facts pages.

You can even occupy yourself at home by coloring in one of our free printable butterfly coloring pages.



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