Rare Butterfly Found at Burrow’s Run Preserve

Jim White, Associate Director, Land and Biodiversity
Top wing view

Milbert's Tortoiseshell Burrows Run Preserve 28 September 2009 11

Finding or observing a rare or uncommon plant or animal is one of a naturalist’s greatest joys. I for one have spent many hours searching high and low for rare birds, herps, and insects. However, many times rarities turn up when you don’t expect them and sometimes they are found by the unsuspecting.

One such find happened on September 28, 2009 at the Delaware Nature Society’s Burrows Run Preserve in northern Delaware. During the “Life of the Monarch Butterfly” program being taught that morning to students from The Pilot School, one of the children netted a butterfly that looked unusual to the Teacher-Naturalists (TNs) leading the program. One of these TNs, my wife Amy, realized that she had never seen this type of butterfly before and decided to keep it in the collecting jar until she could make a positive identification. Moments after the school group left the preserve, Amy and fellow TN Judi VanderWerff were able to match the butterfly to one in Elton Woodbury’s Butterflies of Delmarva field guide. And sure enough, it was a butterfly very rarely encountered in our area, called a Milbert’s Tortoiseshell Nymphalis milberti. This handsome butterfly is mostly dark on the upperside except for a wide, bright orange band near the outer edge of the wings. It typically ranges well north of Delaware, usually in the mountains, and also in the western U.S.. Considered a stray in the mid-Atlantic region, this individual possibly was blown down from the Appalachian Mountains. This great find brings the total number of butterfly species found at the Burrows Run Preserve to fifty-four. So stay alert and you may just be the one to find the next rare critter in our area!

3 thoughts on “Rare Butterfly Found at Burrow’s Run Preserve”

  1. With those amazing eye spots the wing and body resemble a screech owl face- great defense from a hungry bird!

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