Early April, 2020, Casey and I head to the southwest corner of the state looking for multiple subjects. Our primary target of this trip was to check for caterpillars of a rare subspecies of the Baltimore Checkerspot (Euphydryas phaeton ozarkae). This subspecies occurs primarily in the Arkansas Ozarks, but can be found in extreme southern Missouri.
The main distinction that separates this purported subspecies is habitat and host plant preference. The primary habitat for E. phaeton phaeton is marshy wetlands, while E. phaeton ozarkea prefers oak woodlands. The primary host plant for E. phaeton phaeton are the turtleheads (Chelone sp.) while E. phaeton ozarkea primarily uses false foxglove (Aureolaria grandiflora). These animals will overwinter as caterpillars and then will often find new host plant species the following year – as shown in these photographs, they are using lousewort (Pedicularis canadensis). They will then pupate in May to June of their second year.
Browsing the literature, there seems to be some who question the legitimacy of the subspecific status of of E. phaeton ozarkae. Is this simply a case of an opportunistic generalist finding new ways to make a living in varying habitats, or is there a concrete genetic distinction between these two? From what I’ve been able to tell, there does not seem to be a consensus. If you are aware of any newer literature that might shed light here, please let me know.
-OZB
A Thousand Acres of Silphiums 