USING EXUVIA TO MONITOR POPULATIONS AND EMERGENCE PATTERNS OF THE ENDANGERED HINE'S EMERALD DRAGONFLY

S. E. Foster^1,2 and D. A. Soluk^1,2. ¹Department of Natural Resources and Environmental Sciences, University of Illiois at Champaign-Urbana, Champaign IL 61820. , ²Illinois Natural History Survey, 607 E. Peabody Dr. Champaign IL 61820.

The Hine's emerald dragonfly, Somatochlora hineana is the only federally listed dragonfly and is one of only four aquatic insects protected under the Endangered Species Act. Understanding the timing and duration of emergence is an essential link in our knowledge of adult and larval ecology. Emergence patterns of Somatochlora hineana were monitored from June 12, 1999 to August 16, 1999, at Mud Lake State Natural Area, in Door County, WI. Exuvia were collected by intensively examining 6- 2x2 meter plots in typical larval habitat every 4 days. Exuvia were first collected on June 22, 50% of emergence occurred by June 30 and 90% by July 5, 1999. These dates coincide with the adult flight season, which is typically from late June to August. The sex ratio at emergence did not differ significantly from unity (48.15% males, p= 0.847) and the emergence patterns were synchronous between the sexes. The predicted number of emerging Somatochlora hineana from larval population estimates was not significantly different from that estimated from exuvial counts. Because they minimize sampling effort and impact on the habitat, exuvial surveys may become an important tool in monitoring populations of threatened or endangered dragonflies in complex wetland mosaics.