Degree-Day Prediction of Adult Emergence of Photinus carolinus (Coleoptera: Lampyridae)

The synchronous display of the firefly Photinus carolinus</it> Green in the Great Smoky Mountains National Park has been enjoyed by park visitors and studied by scientists and naturalists for the past 17 yr. A degree-day model is presented offering a means of more accurately predicting the display season of P. carolinus</it> to facilitate advance planning required for researchers and the management of the thousands of nightly visitors who come to witness the peak firefly display. A modified growing degree-day (mGDD) model (base 50°F, starting date 1 March) (centigrade equivalent base 10°C, denoted mGDDC) provided the best fit to phenology data collected over a 15-yr period. The predictive model yielded the following values for P. carolinus</it> phenology: male emergence, 838.6 mGDD (range, 776–922)/465.9 mGDDC (range, 431–512); “good” display, 992.5 mGDD (range, 931-1075)/551.4 mGDDC (range, 517–597); female emergence, 1068.8 mGDD (range, 956-1224)/593.8 mGDDC (range, 531–680); and peak male display, 1094.2 mGDD (range, 1020–1182)/607.9 mGDDC (range, 567–657). The accuracy and range limits of using calendar dates versus degree-day values are presented. Additional degree-day values are provided for 14 other local firefly and 1 phengodid species to broaden the applicability of using degree-days to aid in prediction of adult firefly seasons.