Western Great Lakes Bird & Bat Observatory

Headquarters at Forest Beach Migratory Preserve

RARE DRAGONFLY AT FBNP

By Freda van den Broeck

The first tangible evidence of the successful breeding of a rare-to-Wisconsin dragonfly, Anax longipes (Comet Darner) was discovered last summer at the Forest Beach Migratory Preserve in Ozaukee County in the form of a single exuvia (the cast off exoskeleton from which the adult dragonfly emerges).  Although adult Anax longipes have been reported at a few sites in Wisconsin over the past fifty years, no breeding populations have previously been observed.

The Comet Darner, a large dragonfly with a bright green thorax and red abdomen, is more commonly encountered in southern and eastern United States.  Its presence in small numbers in Wisconsin raises the question of whether this dragonfly is an occasional migrant or vagrant in Wisconsin, or if small breeding populations might eventually be discovered.  This question is addressed in an article that was recently published in Argia, the quarterly news journal of the Dragonfly Society of the Americas, entitled “What is the Incomparable Anax longipes (Comet Darner) Doing in Wisconsin?” by Robert DuBois and Freda van den Broek. After considering the observational data, known behavioral patterns and the theory of metapopulations, Robert DuBois concludes that the existence of small but persistent, interacting subpopulations is the most likely explanation for the presence of Anax longipes in Wisconsin.  A small breeding population of Anax longipes at Forest Beach Migratory Preserve would represent the most northwesterly range of this species in North America to date.