ABS 2022
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Environmental Correlates of the Setae Coloration of the Woolly Bear (Pyrrharctia isabella) Caterpillar
Haider Mehdi1, Christine Urbanowicz2, Beth A. Reinke1. 1Northeastern Illinois University, Chicago, Illinois, United States; 2Independent Researcher, Washington DC, Virginia , United States

Melanin-based color expression in insects has been demonstrated to vary by temperature. The Woolly Bear (Pyrrharctia isabella) caterpillar is widespread across North America where it is exposed to a variety of temperature conditions. The Woolly Bear has a distinctive setae color pattern with a central orange band between two black bands. The length of the central band has been anecdotally attributed with predicting upcoming winter severity. In this study, we aimed to identify if there is a relationship between the Woolly Bear’s setae color expression and environmental variables. We acquired research-grade photos and metadata of individual Woolly Bears distributed across the contiguous United States from 2010 to 2019. We measured the relative length of the orange band with digital image analysis and collected monthly mean temperature data for the same time frame. Testing the Woolly Bear’s reliability as an indicator of upcoming winter severity provides scientific rigor for an attribution that is currently strictly anecdotal. Also, identifying plausible correlates can open the door to experimental work identifying the function of setae color variation in Woolly Bears.