Effects of wind speed, wind direction, and temperature on flight patterns of the bog buck moth (Saturniidae: Hemileuca maia)

Populations of the Bog Buck Moth (BBM) (Saturniidae: Hemileuca maia), an endangered species of New York State, have been monitored since 1998, by counting adults during the peak flight period in September. Flight patterns are thought to be sensitive to temperature and wind speeds, but to date, only general conditions, including a single daily temperature measurement and wind speed values estimated using the Beaufort index, have been used to determine suitable monitoring conditions. Increased precision in measurement of temperature and wind speed and their effects on the BBM would improve population monitoring by establishing the ideal weather for flights and helping determine optimal location and orientation of transects. This study focused on a site in which a population of the BBM is subdivided into two sub-populations separated by about 100 meters of inhospitable terrain. Temperature, average wind speed and maximum wind speed associated with flight counts can be measured and compared at the same time intervals and on the same days for both sub-populations. This comparative approach allows analysis of specific effects of temperature and wind speed on BBM flight patterns in both sub-populations. We found that clear, sunny days accounted for the majority of BBM flight counts. Wind speed is a critical factor in BBM flight; as wind speed increased, flight count increased as well. Temperature was less important, as many BBM were counted at temperatures below the supposed minimum flight temperature of 18ºC. Prevailing wind direction also appears to be important relating to fen orientation and monitoring locations.