Correlation of body size of moths captured by light trap with nine environmental variables

Abstract

A single light trap in southern Georgia, USA, operated 29 times for two consecutive days over a 13-month period, captured almost 12,000 moths in six body length categories. Increasing size of moths was related to decreasing number of individuals captured. The smallest moths were the most frequently captured from late spring to early fall, and the least frequently captured at other times of the year. The smallest size (<6 mm) showed capture values widely divergent through time, whereas the intermediate category (11-15 mm and 16-20 mm) size values were the least divergent through time, suggesting that the smallest sized moths were the group most affected by environmental variables. The largest size categories, 21-25 mm and 26-30 mm, represented less than four percent of the total captures and were most frequently captured during the coldest temperatures and during rain. Environmental conditions the six days prior to trap operation were not consistently similar to those conditions prevailing during trap operation and in some cases did affect trap captures. Maximum temperature during trap operation was the best single explanatory variable for the occurrence of all captured moths, whereas minimum temperatures during trap operation was the best explanatory variable for the smallest size class, and rain prior to trap operation was the best single explanatory variable for the intermediate size classes.