Common Buckeye

by Kristen Sevick

Order: Lepidoptera (butterflies and moths)

Family: Nymphalidae (brush-footed butterflies)

Species: Junonia coenia (common buckeye butterfly)

How to identify:

Adults: As with most insects, common buckeye adults have six legs and four wings. Their wingspan ranges from 1.5 to 2.75 inches. Their front wings have orange bars near the leading edge and eyespots near the rear. Their back wings have two eyespots and orange spots near the rear (Alabama Butterfly Atlas, 2023). 

Advanced ID: The common buckeye is in the family Nymphalidae, the brush-footed butterflies that vary in size and color. 

Caterpillars: Caterpillars grow up to 4 cm (Dole, 2003). The bluish black body is covered in blue or black branched spines. They can have beige spots laterally and orange spots dorsally (Texas A&M AgriLife Extension, n.d.). Common buckeye caterpillars have six thoracic true legs anteriorly, and a pair of orange prolegs on each abdominal segment (Critney, 2002). They have mandibulate mouthparts. 

Adults: Adults have triangular, wide forewings, with their front legs being reduced. The hindwings have distinct venation, consisting of two anal veins, a humeral vein, and a discal cell, which appears towards the base of the hindwing. Adults have haustellate mouthparts, consisting of a coiled proboscis and developed labial palps. Antennae are very long and thin, being apically knobbed (Borer & White, 1970). 

Ecology

Metamorphosis Type: Complete metamorphosis: egg, larva, pupa, adult. Larvae often look very different from adults 

Geographic Range: Common buckeyes are native to New Jersey; however, they can be found as far north as Southern Canada, to as far south as Mexico and Bermuda (Critney, 2002). Midwest and east coast populations overwinter in Florida and the Deep South (Missouri Department of Conservation, n.d.). This species is not commonly found on the west coast of the United States.

Habitat: The common buckeye can typically be found in grassy fields, meadows, parks, pastures, or undisturbed areas with their food sources close by (Critney, 2002).

Trophic Level: Herbivore: consumes plants.

Food: Buckeye are specialists (feed on only a few host plants) on plants like plantains and toadflax that contain toxic compounds called iridoid glycosides (Critney, 2002). Caterpillars use hard mouthparts called mandibles to chew leaves (NCSA&LS, 2015), and adults use their straw-like proboscis to drink liquids- primarily nectar (Connor, 2020). Butterflies will also drink fluids from mud, puddles, rotting fruit, or even scat. (Connor, 2020; Critney, 2002; OSU, 2014)

Why should we care?

Human Uses: Common buckeyes are useful to us in three main ways. (1) As they search for nectar, the butterflies pollinate their host plants. (2) Common buckeyes are very pretty, and many people enjoy watching them. They contribute to insectariums or entomological museums, interactive butterfly sanctuaries, works of art, and popular culture. (3) These butterflies can also be used to teach migration patterns, life cycles, and even problems associated with climate change.

Pollinators: Since common buckeyes are host specialists, the butterflies are very important pollinators to several of our ornamental flowers and wildflowers (Critney, 2002). They land on one plant, which allows their legs or mouth to pick up pollen and transfer it to another plant. 

Conservation Status: Common buckeye currently are not listed as endangered or threatened.  However, like many other species, they are negatively affected by deforestation, habitat loss (e.g., construction and agriculture), and climate change (Walker, 2020).

How we can help: Sometimes fixing problems can feel overwhelming, but in the case of pollinators, there is much we can do to help! 

1. Plant a pollinator garden using native plants. Even a small garden can make a big difference- including in urban areas.  Use this website and this Urban Habitat Assessment tool to get started.  Arrange your plants in clusters (rather than individual plants separated throughout the garden). Many species, like the common buckeye, are active in the fall, so include plants that flower throughout the season (NJ Division of Fish, Game, and Wildlife, n.d.). 
2. Provide a puddling station for butterflies; a simple version is a saucer filled with moist sand or soil; then add a small amount of composted materials or overripe fruit as a nutrient source (Florida Wildlife Federation, 2020). 
3. Avoid pesticides in your own garden (Xerces Society, n.d.), and purchase more organic foods to support organic farmers. 
4. Sign the Pollinator Protection Pledge and / or add your garden to the Homegrown National Park, and put up a sign to let others know.  We can make a difference!

Did you know?

• The common buckeye has large, dark eyespots present on both the front and back wings. Butterflies are vulnerable when they are basking, and these eyespots help ward of predators (e.g., birds). (Dunson, 2018)
• Buckeye caterpillars specialize on plants, such as plantain (Plantago, not the cooking plantain), that make special chemicals called iridoid glycosides. Caterpillars eat leaves and adults drink nectar of these plants, taking in and storing the toxic chemicals in their bodies. Predators then avoid these bad-tasting insects. (Richards et al., 2012)

Images Cited

Photo 1: Judy Gallagher. 2020. Creative Commons | Link 

Photo 2: John Flannery. 2011. Creative Commons | Link

Photo 3: Vicki DeLoach. 2016. Creative Commons | Link

Photo 4: Lisa Brown. 2008.  Creative Commons | Link

Photo 5: Judy Gallagher. 2020. Creative Commons | Link

Photo 6: Lisa Brown. 2008. Creative Commons | Link

Photo 7: William Lynch. 2010. Creative Commons | Link

Photo 8: Jazminator. 2013. Creative Commons | Link

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