Red-spotted Purple Butterfly in Tyler State Park, PA. MikeParker at en.wikipedia [CC BY-SA 2.5 (https://creativecommons.org/licenses/by-sa/2.5)]

Red-spotted Purple Butterfly: How to Find and Identify It

Red-Spotted Purple butterfly (Limenitis arthemis astyanax). Nymphalids (Brushfoot family. Photo by Donna L. Long.
Red-Spotted Purple butterfly (Limenitis arthemis astyanax). Nymphalids (Brushfoot family. Photo by Donna L. Long.

I often get the Red-spotted butterfly confused with Pipevine Swallowtails, Spicebush Swallowtails or Black Swallowtails.

If the wings are closed, Red-spotted Purples look similar to White Admirals (Limenitis arthemis arthemis). In fact, the Red-spotted Admiral and the White Admiral are considered two different forms of the same species. The two forms mate and hybridize freely.

The only cure for my confusion is a little research. 

Where to Find Red-spotted Purple Butterflies

The White Admiral is found in a more northern range than the Red Admiral. The White Admiral is found in Canada, Alaska, and the subarctic.

The two forms, White Admirals and Red-spotted Purples interbreed and overlap in an area which includes from Minnesota to Pennsylvania to Maine. In the overlapping area the hybrid offspring may exhibit a combination of traits from both forms. 

The Red Admiral has a more southern the area below the Great Lakes to Florida. The Red-spotted Purple occurs mainly in the Eastern half of the United States, from Pennsylvania west to the mid-west, southward to eastern Texas, east to Florida. 

The butterfly is medium-sized with rounded dark wings. There several rows of white spots along the hind-edge of the wings. And four or so spots of orange above the white. The dark wings probably soak up the warmth of the Sun which allows the White Admiral to live as far north as Alaska and subarctic Canada. Canada doesn’t have that many butterfly species and the White Admiral is one of them.

Look for both forms at the edges of boreal or deciduous forests. They like forest edges, open fields, and scrubby habitats. The Red-spooted can often be found along coastal plains. The males often visit mud puddles.

Red-spotted Purple Life Cycle

The Red-spotted Purple’s life cycle season spans from May through October. In the norhern part of its’ range tthere is 1 generation. In he mid-part of its’ range there is 2 generations and three generations in the southern range.

Adult Life Cycle Stage
Adults feed on sap, fruit, flower nectar, carrion, dung, honeydew, decaying wood, among other substances. The Adult lives for 6-14 days.

Mating
Male Red-spotted Purples perch on trees and tall bushes and wait for a female to pass by.

Egg Life Cycle Stage
The eggs are grayish-green. The eggs are covered with dimples like a gold golf ball. A single egg is laid on the topside tip of the hostplant leaf, often of a young plant. The eggs hatch in 4-9 days. There are two broods in the north; and 2-3 broods in the south.

Larva of Limenitis ursula (Red-spotted Purple)
Larva of Limenitis ursula (Red-spotted Purple) from Moths and butterflies of the United States (1900) by Sherman F. Denton (1856-1937). Digitally enhanced from our own publication.

Caterpillar (larva) Life Cycle Stage
The larva is brown, green or whitish-green and sometimes has green around the saddle are of the body. They look like bird droppings. Pointy blackish horns jut out from both sides of the head. The antennae have prickles along  their lenght. The caterpillar lives 3-4 weeks before pupating. The Pupa last 7-14 days. The larva feed at night.

 

Host Plants
Larva eat many kinds of dicotyledonous plants. Common hostplants include Wild cherry, aspens, poplars, cottonwoods, birches, willows, hawthorn, serviceberry, basswood and deerberry.

Chrysalis of Limenitis ursula (Red-spotted Purple)
Chrysalis of Limenitis ursula (Red-spotted Purple) from Moths and butterflies of the United States (1900) by Sherman F. Denton (1856-1937). Rawpixel [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]

Chrysalis (Pupa) Life Cycle Stage
Red-spotted Purple pupa is slightly different from the White Admiral. But again the two species interbred. The red-spotted pupa or chrysalis is yellowish-brown and pinkish and mottled dark green and gray. It looks like a bird dropping, much like the caterpillar does. The antennnae have prickles.

Overwintering
The Red-spotted Purple overwinters as larva. The larva born in late summer spend the winter in a hibernaculum made from a folded leaf. The leaf is rolled and looks like dead. The larva overwinter in the instar stage of development.

Red-spotted Purple Butterfly in Tyler State Park, PA. MikeParker at en.wikipedia [CC BY-SA 2.5 (https://creativecommons.org/licenses/by-sa/2.5)]
Red-spotted Purple Butterfly in Tyler State Park, PA. MikeParker at en.wikipedia [CC BY-SA 2.5 (https://creativecommons.org/licenses/by-sa/2.5)]

Quick Facts About the Red-spotted Purple

Common name: Red-spotted Purple
Scientific name: Limenitis arthemis astyanax
Wingspan and Flight Style: Averages 3.2 inches, strong graceful flight
Family: Nymphalids (Brush-footed)
Range: East, South, Southeast, Midwest, Texas and New Mexico.
Habitat:

Open woods, the edges of woods and open fields

Host plant(s) Varies widely. Wild cherry, aspens, poplars, cottonwoods, birches, willows, hawthorn, serviceberry, basswood and deerberry.
Adult food: Nectar, visits mud puddles for minerals
Note: Blue on hind wind, no tails. Looks like a White Admiral or a Pipevine Swallowtail.

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