Pollinators

Miami Blue Butterfly

Cyclargus thomasi bethunebakeri

Once common along the entire South Florida coast, now reduced to a few remote islands in the Florida Keys.

Illustration of a Miami blue butterfly ambassador — very small butterfly, bright blue above and pale grey below with a white band and a small orange-and-black eyespot — on a nickerbean vine in coastal Florida scrub. — Illustrated Species Ambassador — original artwork, not a photograph

Illustrated Species Ambassador

Cyan — Miami Blue Butterfly

I'm Cyan, an illustrated ambassador for the Miami blue butterfly. I was once common along the whole South Florida coast. Now I hold on in a few remote keys.

One fact worth knowing: The Miami blue, once widespread along the South Florida coast, is now reduced to a handful of remote islands in the Florida Keys.
What I depend on: I depend on nickerbean thickets for my caterpillars, open sunny coastal scrub, and the absence of invasive fire ants.
My greatest threat: My greatest threats are coastal habitat loss, hurricanes and invasive ants.
One way you can help: If you live in South Florida, plant nickerbean and native coastal legumes, never collect butterflies in the Keys, and support targeted rather than broadcast mosquito spraying.

Pollinators at risk →

This ambassador is an original illustration created for this project. It is an educational character, not a documentary image, and its statements follow the sourced record on this page. Artwork and rights record

Why this species matters

The Miami blue shows how quickly a common coastal species can be reduced to a handful of islands by development, and how a single hurricane can then threaten everything that remains.

If it disappears: It would be a documented U.S. butterfly extinction in a heavily developed and closely watched region, and coastal scrub would lose a specialist pollinator.

Conservation status

U.S. Endangered Species Act: EndangeredEmergency listed in 2011 and listed as endangered in 2012.Last verified 2026-09-08
Florida: State endangeredLast verified 2026-09-08
IUCN Red List: Not separately assessed at the subspecies levelLast verified 2026-09-08

Population

Extremely small. Known wild populations are restricted to a small number of islands in the Key West National Wildlife Refuge, with counts reported by survey rather than as a range-wide total.

Trend: Unknown

As reported: USFWS and University of Florida monitoring, recent survey seasons

Source: U.S. Fish and Wildlife Service; Florida Museum of Natural History McGuire Center

Uncertainty: Numbers fluctuate sharply with storms and host plant condition; single-year counts should not be read as a trend.

Historical: Formerly ranged along coastal southern Florida from the Daytona area south through the Keys and was once considered common.

Fragmentation: The species now exists on a handful of small islands with no natural connectivity to the mainland.

Range and distribution

Historic range: Coastal southern Florida, the Florida Keys, and the Dry Tortugas.

Current range: A few islands within the Key West National Wildlife Refuge, plus reintroduction attempts elsewhere in the Keys.

Range contraction: Lost from essentially the entire mainland coast.

Regions occupied

Lower Florida Keys
Historic range along both Florida coasts

Habitat

Primary habitat: Coastal tropical hardwood hammock edges, beachside scrub, and open sunny areas with host plants.

Breeding habitat: Larvae feed on nickerbean (Caesalpinia bonduc) and, historically, blackbead and other legumes.

Feeding habitat: Adults nectar on small coastal flowering plants.

Critical habitat: No critical habitat designated.

Habitat dependencies

Nickerbean thickets in coastal areas
Open, sunny coastal scrub
Absence of invasive fire ants

Biology and ecology

A pollinator of coastal plant communities and an indicator of intact coastal scrub.

Key relationships: Like many blues, larvae are tended by ants — but invasive fire ants attack rather than tend them.

Size: Wingspan under one inch.
Lifespan: Adults live roughly a week.
Diet: Nickerbean and related legumes as larvae; nectar as adults.
Reproduction: Multiple broods per year in the subtropical climate.
Offspring: Dozens of eggs per female.
Breeding frequency: Several generations annually.

Primary threats

Habitat loss
Coastal development removed nearly all mainland habitat in southern Florida.
Hurricanes
A single major storm can destroy host plants and populations on the small islands where the species remains.
Invasive species
Red imported fire ants prey on eggs and larvae; invasive plants displace nickerbean.
Mosquito control spraying
Aerial insecticide application in the Keys kills non-target butterflies.
Sea level rise
The remaining island habitat is low-lying and directly threatened by rising seas.
Illegal collection
Rarity increases the value of specimens to collectors.
Small population effects
Very low numbers reduce genetic diversity and increase vulnerability to any single event.

Conservation and recovery

Programs and efforts

Captive rearing at the Florida Museum of Natural History McGuire Center for Lepidoptera
Reintroduction attempts at multiple Keys sites
Host plant (nickerbean) restoration in the Keys
Coordination with mosquito control districts to limit spraying in butterfly habitat

Protected areas

Key West National Wildlife Refuge
Great White Heron National Wildlife Refuge
Bahia Honda State Park (historic site)

Legal protections

Endangered Species Act
Florida state endangered listing
Refuge access restrictions on occupied islands

Measurable progress

A captive population has been established and maintained
Nickerbean plantings have expanded available habitat

Continuing challenges

Reintroductions have repeatedly failed to establish
Hurricanes are unpredictable and increasingly severe
Habitat is a few acres on remote islands

How people can help

What individuals can do

Plant nickerbean and native coastal legumes if you live in South Florida
Never collect butterflies in the Keys
Support targeted rather than broadcast mosquito control

What communities can do

Encourage mosquito control districts to adopt butterfly-safe treatment windows and buffer zones

Educational actions

Use the Miami blue to teach how quickly a common species can become critically rare

Habitat support

Support coastal hammock and scrub restoration in the Keys

Organizations and programs to learn about

USFWS South Florida Ecological Services
Florida Museum McGuire Center
Florida Fish and Wildlife Conservation Commission

Educational notes

Believed possibly extinct after Hurricane Andrew in 1992, then rediscovered in 1999.
An unusually clear case where invasive ants, not habitat alone, drive the decline.