By Dan Zarlenga, Missouri Department of Conservation
Photo caption: The common buckeye butterfly perches on a blade of grass, ready to stare down a predator! Photo by Dan Zarlenga
Eyeing the Buckeye
Did you ever wish you had eyes in the back of your head? That would be nature’s ultimate backup camera! While we humans only have one pair of eyes, there’s a creature that does have eyes on the back of its wings.
The common buckeye butterfly is a resident in Missouri during the summer, when it lives and breeds here. But they cannot survive the Show-Me-State’s colder winters, so each year a brand new batch migrates here from states in the deep south, where winters are milder. A completely different generation of buckeyes arrives in Missouri sometime in mid-to-late May each year.
While butterflies like monarchs get a lot of attention, common buckeyes are fascinating in their own right. Like their more famous counterparts, buckeyes also provide important pollination services. They are not in any way related to buckeye trees, however.
Though its rather drab brown color may not be too showy by itself, what set’s these butterflies apart are the unusual eyespot markings on their wings. Each wing has the spots, giving this butterfly as much as eight extra “eyes”. Other distinctive markings include orange bars on the leading edge of the forewing and off-white forewing bands. Drab brown notwithstanding, the common buckeye overall is quite an attractive butterfly.
Despite having all these extra eyes, the only pair that can actually see anything are the ones on the buckeye’s head. The eyespots on the wings are merely markings.
Buckeye butterflies tend to be found in open, sunny areas, where avoiding predators is always a concern. Biologists believe that the bold eye markings on their wingbacks may serve to confuse or even scare off would-be predators, at least long enough for the buckeye to escape. You might say these butterflies give the evil eye to their enemies—or several of them actually. In any case, having eyes on the back of your wings can be a big help. It’s a “staring contest” that the buckeye must win to survive.
What protects the common buckeye when it’s in the larval, or caterpillar, stage of life are the host plants they feed on. While caterpillars, buckeyes live on and eat plants that contain toxins that turn off would be attackers. At this stage, the caterpillars are bluish black, with yellow to creamy orange stripes and spots with short spines that are metallic bluish black.
When the adult butterflies eventually leave the chrysalis, their wings are soft, making them highly vulnerable. At this time, they make further use of these toxins collected in their bodies by expelling them with waste products at potential predators. This is an important line of defense until the buckeye’s wings fully develop and those eyes “open up”.
As adults, buckeyes tend to hang out on plants of the aster-sunflower-daisy family.
So next time you’re exploring some flowers in a warmer area, perhaps a glade or sunny field, don’t be surprised if you see several sets of eyes looking up at you. The common buckeye might be taking a good look at you without actually seeing. It’s just showing off a unique survival strategy. For this butterfly, the “eyes” truly have it.