Baltimore Checkerspot Butterfly

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The rare Baltimore checkerspot is a beautiful butterfly that can be spotted (if you’re lucky) around wetlands in Northeastern Illinois.

This distinctive butterfly is just one of the species that has benefited from the Peggy Notebaert Nature Museum of the Chicago Academy of Sciences' pioneering work to bolster populations of rare and endangered butterflies native to the region.

Euphydryas phaeton4a

About the Baltimore Checkerspot Butterfly

Baltimore checkerspots are identifiable by their velvety black wings with bright dotted coloration, most often in the months of June and July. Unfortunately, their beauty is becoming rarer due to lost and degraded wetland habitats and plant species, which is why the scientists at the Peggy Notebaert Nature Museum are working hard to sustain them. For biologist Doug Taron and his team, breeding the checkerspot and sustaining them throughout the winter months for release in June is a key goal in their work preserving this colorful species.

"Mastering the Baltimore checkerspot’s hibernation patterns will open the door for protection and conservation of many butterfly species."


What are we doing to help?

The Illinois Butterfly Monitoring Network has monitored the Baltimore checkerspot population at Bluff Springs Forest Preserve in Elgin since 1988. However, due to drought conditions in 2012, the population of this butterfly disappeared and we haven’t seen any in the region since.

To combat this absence, the Museum is raising Baltimore checkerspot caterpillars to release at the preserve. The most challenging part is keeping the caterpillars over the winter. Like their swampy habitat, the caterpillars spend winter in cold environments with a high level of humidity. This is a difficult balance to replicate in the lab, as typical cooling mechanisms such as refrigerators also create a dry environment.

Scientists have developed a container that will address this issue using a porous material that absorbs water and makes the environment more humid. For the Spring 2018 release, they placed the caterpillars in these containers on the roof during the winter.


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    After their annual mating flight, female butterflies lay their eggs on the turtlehead plant. This is the only native plant on which Baltimore checkerspots will lay their eggs.

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    Once the eggs hatch, the caterpillars will build a communal web where they will live and feed together. They eat a narrow range of plants that includes swamp betony and valerian.

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    Throughout the summer, the web grows lower and lower, eventually reaching the ground. The caterpillars become dormant and enter a hibernation-like state by late fall. This is where the caterpillars spend the winter.

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    In early spring, the caterpillars will wake up and begin feeding again for a few weeks.

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    By late spring, the caterpillars will each form a chrysalis. Two weeks later, in late May/June, the adult butterflies will emerge. During these months, our scientists go into the field to collect female butterflies to lay their eggs in the lab. Sometimes, the butterflies even lay their eggs in the car on the way back to the lab!

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Meet the Expert

Doug Taron, PhD, is the Chief Curator Emeritus of the Chicago Academy of Sciences. He founded the Illinois Butterfly Monitoring Network in 1987, a volunteer organization that monitors the health of butterfly populations in nature preserves.

“The Baltimore checkerspot butterflies live in these great big clusters. Growing up, I would only see them in my grandmother’s yard in New England. They are a large part of what sparked my interest in butterflies as a kid.”


The Peggy Notebaert Nature Museum of the Chicago Academy of Sciences' work with the Baltimore checkerspot is generously supported by Patagonia and the Vanderpoel Foundation.

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