The following article was written by Kennedy Zittel, a Naturalist at the Woodland Dunes Nature Center.
Woodland Dunes contains a variety of wetland habitats, including the area around the nature center building itself. Wetlands are incredibly important habitats, around 75% of all Wisconsin wildlife depend on a wetland at some point during their lifecycle. While walking across the back parking lot last week, Max and I stumbled upon a wetland-dependent species, a Baltimore Checkerspot, as it sat in the sunny gravel.
The Baltimore Checkerspot (Euphydryas phaeton) is a common wetland butterfly. This beautiful little butterfly has a row of orange spots on the edge of their black wings as well as several rows of white spots with a few orange ones mixed in near their body. They are often found in open wet meadows, as well as adjacent upland areas where adults nectar on black-eyed susans, milkweed, and more. This butterfly is said to be incredibly docile, which certainly explains why we were able to walk right up to it to get a closer look (and a few pictures) before it calmly fluttered away towards Willow Trail.
Their larvae have alternating horizontal bands of orange and black with short spines along their body. Caterpillars feed on white turtlehead (Chelone glabra), a lovely native wetland plant named after its flowers that resemble a turtle’s head shape. White turtlehead contains toxic chemicals called iridoid glycosides, once the caterpillars feed on this plant they become toxic/bad tasting for any predators. Similar to how monarch caterpillars feed on milkweed, which also contains toxins that then in turn make them unappealing to predators too.
Adult females lay hundreds of eggs on the undersides of their host plant’s leaves. These eggs begin yellow and then slowly turn red before they hatch. The newly-hatched caterpillars spin communal silk-like webs around their host plant that help keep them safe from predators and the weather. They continue to feed on the plant from inside their web, growing as they eat top – bottom along the plant. Unlike many other butterfly species, Baltimore Checkerspots overwinter as larvae. Near the end of summer, their caterpillars stop eating and spin a thicker web where they remain temporarily. Towards the end of fall, they leave that web to spend winter on the ground underneath the leaf litter. They will curl up, either individually or in small groups and use natural antifreeze-like chemicals within their bodies to freeze and thaw with the outside temperature without harm. The following spring, around April, as the weather warms the caterpillars emerge, finish feeding, and transform into one of the most beautiful chrysalis – blue and white in color and speckled with orange and black spots. Two weeks later, the adult butterfly emerges. The adults have a short lifespan, only two – three weeks to find a mate and lay eggs.
Baltimore Checkerspots are univoltine, meaning they only have one brood per year. Along with their specific host plant requirements, this puts them at risk of population decline as wetlands decline in our state. According to the Wisconsin Wetland Association, around half of the wetlands in Wisconsin have been lost since the 1800s. It is so important to protect our wetlands, not only for this lovely little butterfly and the rest of the 75% of wildlife that use wetlands too, but also for the countless benefits that wetlands provide for ourselves and the world around us. If you would like to try and see this beautiful little butterfly for yourself, a walk through the wetland along Cattail Trail or Willow Trail is a great place to start. Even if the butterflies evade your sight, you will be greeted with the countless other animals and plants that call wetlands their home.
