Endangered Insects of North America

About the Endangered Species Act:

Recognizing that many of our nation’s native plants and animals were in danger of becoming extinct, Congress passed the Endangered Species Act (ESA) in 1973. The purpose of the ESA is to protect and recover imperiled species and the ecosystems upon which they depend. It is administered by the U.S. Fish and Wildlife Service (terrestrial and freshwater organisms) and the Commerce Department’s National Marine Fisheries Service (marine wildlife such as whales and salmon). 

Under the ESA, species may be listed as either endangered or threatened. “Endangered” means a species is in danger of extinction throughout all or a significant portion of its range. “Threatened” means a species is likely to become endangered within the foreseeable future. All species of plants and animals, except pest insects, are eligible for listing as endangered or threatened. For the purposes of the ESA, Congress defined species to include subspecies, varieties, and, for vertebrates, distinct population segments.

Today, the Federal Government lists 75 insects as threatened or endangered. 

Threatened and Endangered Insects and Terrestrial Invertebrates of North America

Names link to U.S. Forest Service Environmental Conservation Online System (ECOS)

Year Listed

Ash Meadows naucorid (Ambrysus amargosus)

1985

Bartram's hairstreak (Strymon acis bartrami)

2014

Bay checkerspot (Euphydryas editha bayensis)

1987

Callippe silverspot (Speyeria callippe callippe)

The Callippe silverspot was historically found around the eastern, southern, and western sides of San Francisco Bay, but is now limited to just seven sites. It is found in native grassland and adjacent habitats, where females lay their eggs on the larval food plant, Johnny-jump-up. The causes of the callippe silverspot’s decline are fairly clear: The vast majority of potential butterfly habitat lies under the cities of San Francisco, Oakland, and Berkeley, and what open areas remain within this butterfly’s range are dominated by introduced plant species. Many of these areas are also grazed by cattle, mined, or subject to heavy recreational use. The causes of the callippe silverspot’s decline are fairly clear: The vast majority of potential butterfly habitat lies under the cities of San Francisco, Oakland, and Berkeley, and what open areas remain within this butterfly’s range are dominated by introduced plant species. Many of these areas are also grazed by cattle, mined, or subject to heavy recreational use. The Alameda County population is particularly small and vulnerable. The San Bruno Mountain population occurs on land that, although private, is largely protected from development. This area is also being managed for the conservation of several additional endangered species, including the San Bruno elfin (Callophrys mossii bayensis) and the bay checkerspot (Euphydryas editha bayensis).  The species is imperiled by the current and potential future destruction and alteration of its habitat due to off-road vehicle use, unsuitable levels of livestock grazing, and invasive exotic vegetation. Trampling by off-road vehicles and by horses and hikers could also crush the food plants of the larvae or the adult nectar sources. Use of insecticides may also be a problem.

1997

Carson wandering skipper (Pseudocopaeodes eunus obscurus)

Cassius blue (Leptotes cassius theonus)

Ceraunus blue (Hemiargus ceraunus antibubastus)

Dakota skipper (Hesperia dacotae)

El Segundo blue (Euphilotes battoides allyni)

Named for the dune system that it inhabits, the El Segundo blue has found its home increasingly coveted by humans. Airport construction, oil refining, sand mining, and urban development have all claimed large portions of its dune system habitat. One of the last populations lives adjacent to the Los Angeles International Airport. 

The major threats faced by the El Segundo blue are loss of habitat due to urban and industrial development and declines in its hostplants, seacliff buckwheat. The El Segundo Dunes have been reduced over the decades to isolated fragments, and these patches are now being modified by invasive plants. The wrong buckwheats are competing with the host plant and other invasive species are stabilizing the dunes; prime butterfly habitat is unstable dunes. 

Fortunately, the habitat of at least two butterfly populations are being actively managed by land owners: both Los Angeles International Airport and Standard Oil are taking positive steps to increase host plant numbers and protect habitat. The survival of this butterfly relies on the survival of adequate habitat. The U.S. Fish and Wildlife Service, as well as officials from the Los Angeles International Airport and Standard Oil have undertaken important dune management programs which focus on removing exotic plants and reestablishing native vegetation. The Urban Wildlands Group has applied to the USFWS for an enhancement of survival permit and safe harbor agreement for approximately two acres of bluff habitat on private property in Los Angeles County, California. Several additional sites are currently being examined for their potential as reintroduction sites for the species. A detailed understanding of the vegetation and ecology of the butterfly’s habitat will be needed for restoration and conservation 

1976

Fender's Blue Butterfly (Icaricia icarioides fenderi)

Once thought to be extinct, the Fender's blue was known only from collections made between 1929 and 1937, until it was rediscovered in 1989 by Paul Hammond. Fender’s blue is a butterfly that formerly thrived in the prairies of Oregon’s Willamette Valley, but during the past 140 years an estimated 99 percent of this native prairie has been turned into farmland or otherwise developed.

Habitat loss from agriculture and urban development poses the greatest threat to the Fender’s blue. Another major threat to the butterfly is the invasion of exotic plants. Invasive species, such as Himalayan blackberry and Scotch broom, have been outcompeting and displacing the Kincaid’s lupine and other native wildflowers in upland prairies where the butterflies live.

Scientists are currently engaged in an active research program to study the habitat needs of this butterfly’s host plant. In addition, scientists with the Nature Conservancy, with the help of Xerces Society volunteers, are looking for new populations. Scientific research into breeding the Fender’s Blue butterfly are in their initial stage. Cheryl Schultz, Assistant Professor, Washington State University Vancouver, is heading up this effort.

2000

Florida leafwing (Anaea troglodyta floridalis)

Karner Blue (Lycaeides melissa samuelis)

While the range of the Karner blue extends from New Hampshire to Minnesota, their populations are limited to specialized habitats where wild blue lupine plants (Lupinus perennis) are found. Karner blue caterpillars only feed on wild blue lupine leaves, leaving behind “windowpanes” or a leaf “skeleton.” Wild blue lupines are found in the sandy soils of pine barrens, oak savannas and lakeshore dune habitats. These habitats require fire or other disturbance to maintain the sunny open patches where wild blue lupine is found, and they often support other rare species of plants as well.

Like many members of the Lycaenid butterfly family (the blues and coppers), Karner blue butterfly caterpillars are “tended” by ants. The caterpillars secrete small quantities of a liquid from a gland on the top rear of the caterpillar which provides food for the ants. In return, the ants protect the caterpillars from some predators and parasites. Adult Karner blues feed on the nectar of many plants, including butterfly weed (Asclepious tuberose), leafy spurge (Euphorbia podperae), blazing star (Liatris cylindracea), wild Virginia strawberry (Fragaria virginiana), and New Jersey tea (Ceanothus americanus).

Karner blue butterflies were federally listed as endangered in 1992 because of dramatic declines in populations due to habitat loss and modifications, such as fire suppression. Overall, during the last few years the population of the Karner blue range-wide appears stable. Research on habitat management, dispersal, ant tending, and female egg-laying preferences are helping with the management of the butterfly.

1992

Laguna Mountains skipper (Pyrgus ruralis lagunae)

Lange's metalmark (Apodemia mormo langei) 

This butterfly is known almost exclusively from the Antioch Dunes National Wildlife Refuge, established largely for the butterfly’s protection in 1980. The butterfly’s numbers began to decline early in the twentieth century as the growth of San Francisco led to the dunes being mined heavily for sand. In the early 1900s, the isolated dune habitat in the San Joaquin delta began to experience a dramatic change as human development expanded. Large-scale sand mining and industrial development fragmented the sand dune habitat until only a small portion of the original ecosystem remained. Nonnative grasses and vegetation encroached on the sand dunes to crowd the few remaining endangered plants. By the time the Antioch Dunes Refuge was established, only a few acres of remnant dune habitat supported the last natural populations of the endangered Antioch Dunes evening-primrose (Oenothera deltoides var. howellii), Contra Costa wallflower (Erysimum capitatum var. angustatum), and Lange’s Metalmark.

But, ultimately, one of the biggest problems faced by Lange’s metalmark is a fundamental change in the dune structure. Formerly a dynamic mosaic of open sand and vegetation, the dunes have slowly been stabilized by the removal of sand and by the introduction of plants which have spread over the sand and now prevent much sand movement. Under these conditions, the butterfly’s host plant, naked stemmed buckwheat, does not reproduce well. Its seedlings require open sand to become established.

Maintaining populations of naked stemmed buckwheat is imperative. This can be done via planting, but creating the open, shifting dune conditions appropriate for natural regeneration would be preferable. The remaining dunes within the butterfly’s range should be protected from development and damaging activities. (Currently, PG&E is the only private landowner with butterflies on their property and there is a conservation easement in place).

Lotis blue (Lycaeides argyrognomon lotis)

Miami Blue (Cyclargus (Hemiargus) thomasi bethunebakeri)

Mission blue (Icaricia icarioides missionensis)

Formerly relatively widespread on the San Francisco and Marin peninsulas of northern California, the mission blue is now restricted to only a few sites. Preservation of existing butterfly populations relies on many factors common to butterfly conservation programs: replanting of the hostplant, removal of introduced plants, and protection from excessive recreational use and development. Probably the most important single location is San Bruno Mountain (San Mateo County), where two thousand acres of habitat are being managed by the county department of Parks and Recreation. A habitat conservation plan was developed for rare butterflies, including the Mission Blue, that occur at San Bruno Mountain. Much of the habitat of the mission blue occupies private lands that are slated for housing developments in the City of Pacifica General Plan.

1976

Mitchell's satyr (Neonympha mitchellii mitchellii)

Mount Charleston blue (Icaricia (Plebejus) shasta charlestonensis)

Myrtle's silverspot (Speyeria zerene myrtleae)

Nickerbean blue (Cyclargus ammon)

Oahu tree snail (Achatinella spp.)

Oregon silverspot (Speyeria zerene hippolyta)

Painted snake coiled forest snail (Anguispira picta)

Palos Verdes blue (Glaucopsyche lygdamus palosverdesensis)

Pawnee montane skipper (Hesperia leonardus Montana)

Poweshiek skipperling (Oarisma poweshiek)

Quino checkerspot (Euphydryas editha quino (=E. e. wrighti))

Saint Francis' satyr (Neonympha mitchellii francisci)

San Bruno elfin (Callophrys mossii bayensis)

Schaus swallowtail (Heraclides aristodemus ponceanus)

Smith's blue (Euphilotes enoptes smithi)

Uncompahgre fritillary (Boloria acrocnema)

Taylor's Checkerspot (Euphydryas editha taylori)

Tumbling Creek cavesnail (Antrobia culveri)

GONE FOREVER - Xerces Blue (Glaucopsyche xerces)

Discovered in 1852 - Extinct in 1941

The Xerces Blue butterfly is the first butterfly in North America known to have become extinct due to human disturbance. This butterfly formerly inhabited the sand dune systems of San Francisco until this habitat was almost entirely destroyed by urban development. Ironically, the butterfly's food plant (genera Lotus and Lupinus) is still found at some of the butterfly's former habitat areas. As the butterfly's habitat area was diminished, the species experienced a lack of diversity necessary to cope with the many other environmental factors. Another likely cause was the introduction of the Argentine ant (Iridomyrmex humilis), which displaced the native ant species that shared a symbiotic relationship with the butterfly larvae. In less than one hundred years, the urbanization of the butterfly's home range destroyed the species.

In addition to the Xerces Blue, there are three species and 12 subspecies of butterflies that are extinct in North America and worldwide. 

Here's a link to U.S. Fish & Wildlife Service's list of currently endangered species

What can we learn? Responsible land use through urban ecology is the only way to insure that similar plant and animal species do not meet the fate of the Xerces Blue. Humans share the planet with other organisms and must exercise the wise allocation of natural resources, including land and water.