How to Identify a Blue Butterfly With Orange Spots

Compare the butterfly's size to the change in your pocket. The Karner blue butterfly (Lycaeides melissa samuelis), which has orange markings, is the size as a United States nickel. The wingspan is approximately 1 inch. Eastern-tailed blue butterflies have a slightly larger wingspan, at 1 1/8 inches.

Look at the markings on the butterfly on both sides of the wings. The Karner blue has orange spots near the edges of the wings, on the underside. The northern blue butterfly (Lycaeides idas) has thin black bands and markings near the edges of the wings.

Check the markings on the dorsal (back) wings. On the male Karner blue butterfly, the dorsal wings have black and white bands. Female Karner blue butterflies have brown bands on their dorsal wings.

Look at the underside of the wings. Only Karner blue butterflies have crescent-shaped orange markings in this location. If the orange crescents are present, you can be sure you have a Karner blue butterfly. The eastern-tailed blue butterfly has gray and black markings on the underside of the wings.

Search for a tail. The eastern-tailed blue butterfly (Cupido comyntas) has a thin tail extending from the hind wing.

Check the date. Northern blue butterflies are usually only active in June and July.

Look at the surrounding flora. Karner blue butterflies are often found close to wild lupine. Northern blue butterflies are found near dwarf bilberry.