picture of a male fender's blue butterfly

Blue Butterflies

North American hosts approximately fifty blue butterfly species (Polyommatinae), divided into thirteen genera. Generally small in size, most Polyommatinae species tend to live in limited ranges.

Changing human demographic and development patterns over time placed stress on North American blue butterfly diversity. In fact, of the nineteen different butterfly species listed as either threatened or endangered under the Endangered Species Act, seven of those species are blue butterflies, including the Fender's Blue butterfly.

Consider the case of the Fender's Blue butterfly. Once thought extinct, it was rediscovered in 1989, and in January 2000, the U.S. Fish and Wildlife Service listed it as endangered, under the United States Endangered Species Act.

A prairie (grassland) resident of the Willamette Valley, OR, the Fender's decline parallels the Valley's transition to farmland in the mid-nineteenth century with the arrival of American settlers. Today prairies represent less than one percent of their original expanse.

Because habitat destruction is the source of the problem, habitat restoration will ultimately be the answer to maintaining stability in the current population and enabling their numbers to grow.

State and federal agencies, along with private groups continue working to improve prairie habitat on a myriad of wildlife refuges in the area. Research includes breeding programes for both Kincaid's lupine, the larval plant, along with the Fender's Blue butterfly itself, for the purpose of restoring them in the wild.

The top picture shows the male, with black borders around blue wings. The bottom picture shows the female, from a side view.

Some genera, such as Hemiargus, get represented by only one species, the Ceraunus Blue (Hemiargus ceraunus).

Fairly common in the south, it flies wherever legumes, the larval host plant, grow. Its small size makes it easy to miss in the field.

Reakirk's Blue

Reakirt's Blue (Echinargus isola), another of the single species genera, inhabits grasslands, riparian areas and desert regions of the Midwest, south through Texas, and the lower Rocky Mountain states.

The first image in the composite on the right highlights some small characteristic black spots on the bottom of the wings.

Unlike some of the endangered blue butterflies, Reakirt's are a fairly adaptable species.

The caterpillars feed on a variety of plants in the pea family, making it easier for them to move, if change comes to any one particular ecosystem hosting their food sources.

Cassius Blue

The Cassius Blue (Leptotes cassius), second picture in the composite, one of two native Leptotes species, inhabits Southeast grasslands.

Smaller than average for a blue, with two brightly colored eye spots on the wing's edge, their quick and erratic flight pattern provides the first field identification clue of its presence.

The Larvae feed on a variety of plants including members of the pea and leadwort families. Adults nectar on a variety of flowers.

Polyommatinae genera need not contain a small number of species. Native North American Celastrina, Euphilotes and Plebejus species reach into the double digit range.

Azure Butterflies

By the time the species in the third picture comes up for identification, it's obvious that attention to wing pattern spots and dots determines most blue butterfly identification. The picture represents the Celasreina species, better known as Azures. Chevron marks along the wing edges indicates a Spring Azure (Celastrina ladon).

North American Glaucopsyche species span the alphabet from A to S, with the Arrowhead Blue and the Silvery Blue accounting for the total population.

Arrowhead Blue

The more geographically limited species, the Arrowhead Blue (Glaucopsyche piasus), the first picture in the next composite, easily gets identified by its distinct gray and white wing pattern.

While unevenly distributed, their range extends throughout higher elevation areas of the West.

Like so many of the blue butterflies, lupines serve as the host plant for the caterpillars.

Silvery Blue

The silvery blue butterfly (Glaucopsyche lygdamus) spreads its wings across most of North America.

The second picture presents a side wing pattern, characterized by white, circled spots. It's a good identification clue.

The top view of the female shown in the bottom picture highlights its white bordered wings.

The top side of the male silvery blue's wings show a lighter shade of blue surrounded by a dark border.

Silvery Blues tend to fly spring through summer, depending on elevation, with mountain populations tending to fly during the summer.

The links in the box at the top of the page point to articles with more detailed coverage of four additional Polyommatinae genera.

© 2007-2014 Patricia A. Michaels