American Copper Butterfly

American Copper butterfly

Greetings, BugFans,

The BugLady found this beautiful little butterfly in the dunes at Kohler-Andrae State Park recently. She doesn’t see coppers often, and she always forgets how small they are — a tad smaller than a Pearl Crescent. Coppers are in the family Lycaenidae along with the Blues, Hairstreaks, and Harvesters. 

The first thing to know about the American Copper (Lycaena phlaeas) is that it probably isn’t native. Some researchers believe that it’s the same species as a European-Eurasian-North African butterfly called the Small, Flame, or Common Copper in English, Lille Ildfugl in Danish, Acobreada in Portuguese, and Manto Bicolor in Spanish. Bugguide.net calls it the “the most widespread species of the genus Lycaena, and among the most widespread of all butterfly species.” It is believed that the ancestors of the American Coppers in the Eastern US came over on the boat with the early settlers, probably from Scandinavia, probably in shipments of hay. The other guess is that it’s a Holarctic species — one that is native to the whole top of the world. DNA analysis would answer that question. 

American Copper butterfly

Adults nectar on a variety of flowers, many of them in the composite/aster family. This butterfly found something to like about Spotted knapweed, an invasive that likes poor soils. Caterpillar host plants are two non-native members of the buckwheat/smartweed family — Sheep sorrel (sour dock) and, to a lesser extent, curly dock. The fact that the American Copper’s two main food plants also came over on the boat is considered proof of its non-native status, though some native butterflies do adopt introduced plants. Further, the native plants that are related to Sheep sorrel and curly dock are wetland plants, and this is a butterfly of dry habitats. As their host plants followed the edge of the frontier west, it is said, the American Copper trailed behind.  

In North America, American Coppers are mostly found east of the Rockies, north to the Tundra. They’re not found in the Deep South, except in the mountains, where they eat Mountain sorrel. 

American Copper butterfly

[Quick botanical aside: Mountain sorrel is an alpine plant with its own origin story. Researchers found that it originated in China at least 11 million years ago, moved east into Russia and then into North America by 4 million years ago, west into Western Europe by two million years ago, and that it entered Greenland from both east and west — a circum-arctic species.] 

American Coppers frequent the habitats of their caterpillar food plants — barrens, abandoned fields, powerline and railroad rights-of-way, and especially dry, disturbed spots like vacant lots and road edges. And dunes. The fabulous “Butterflies of Massachusetts” website notes that this is a species that benefited from the clearing of forests for agriculture and timber in the 1700s and 1800s and that it does not do well in heavily developed or landscaped areas.   

They are active, especially on sunny days — fast and erratic butterflies that fly a foot or two above the ground and may also hover or glide — strong flyers that can show up quite a ways from home. They also bask on the ground. Clarence Weed, in Butterflies Worth Knowing (1922) says that they “begin their day’s work early in the morning and continue well into evening. Then they find a roosting-place, head downward on a blade of grass, where they sleep until wakened by the morning sunshine.”  

Females and males look similar, with wingspans of 7/8” to 1¼”. They’re beautiful with their wings closed, and spectacular with their wings open. The downy caterpillars are about ¾” long and may be greenish-yellow or have a rosy trim.     

Males are territorial and feisty, watching for females from perches on vegetation and chasing any insects that fly by. Sources said that they react to the shadows of birds, and renowned lepidopterist Alexander Klots reported seeing a male American Copper go after an airplane. Females select males by landing nearby and displaying their wings, and they mate perched on vegetation. If they fly while coupled, she totes him, rather than the other more common way around.  

Eggs are laid on the upper surface of the host plant’s leaves or stem, and the sluglike caterpillars shelter near the base of the plant by day and feed by night on the underside of the leaf. There are several generations per year, and the final brood overwinters as larvae in leaf litter at the base of the plant, pupating for three weeks in the following spring (though some sources say that they overwinter in the pupal stage). Adults live for two, all-too-brief weeks.

Caterpillars of some of the other Lycaenids consort with ants (they are myrmecophiles) – ants care for them in return for a honeydew-like substance made by the caterpillar. A few sources speculated that American Copper caterpillars might enjoy such a relationship, too, producing chemicals that attract ants. 

Three other items of business:

  • Are you a mosquito magnet? Here’s why.
  • Tis the season – the BugLady walked slowly through a gigantic feeding swarm of Common Green Darners the other day, with dragonflies gliding by close enough to touch.
  • Finally, long, long ago, when she was about eight years old, the BugLady was enthralled by a picture of a Black Witch moth and wished she could see one. Saturday, one flew through her yard — twice — and it was well worth the wait! Watch for more Black Witches if the Atlantic hurricane season heats up.

The BugLady

UWM Land Acknowledgement: We acknowledge in Milwaukee that we are on traditional Potawatomi, Ho-Chunk and Menominee homeland along the southwest shores of Michigami, North America’s largest system of freshwater lakes, where the Milwaukee, Menominee and Kinnickinnic rivers meet and the people of Wisconsin’s sovereign Anishinaabe, Ho-Chunk, Menominee, Oneida and Mohican nations remain present.   |   To learn more, visit the Electa Quinney Institute website.