AVOIDANCE OF DIRECT SUNLIGHT BY ADULT HESPEROPSIS-GRACIELAE (MACNEILL) (LEPIDOPTERA, HESPERIIDAE)

Perched Hesperopsis gracielae (MacNeill) adults were partially or enti rely exposed to direct sunlight (solar radiation), and the response ti mes were recorded when the skippers avoided continued exposure by flyi ng or walking to shade. Of the skippers partially exposed to direct su nlight, those exposed only on their heads, thoraces, and basal portion s of the wings sought shade earlier than those exposed only on their a bdomens and distal portions of the wings. Skippers entirely exposed to direct sunlight sought shade earlier than those partially exposed to direct sunlight. Response rates (inverse of response times) of skipper s partially exposed to direct sunlight, when summed, were equivalent t o response rates of skippers entirely exposed to direct sunlight, infe rring that thoracic and abdominal heating rates were independent and a dditive. Estimated thoracic (0.6 degrees C.s(-1)) and abdominal (0.3 d egrees C.s(-1)) heating rates were comparable to those measured in oth er similarly-sized Hesperiidae. Results indicate that perched H. graci elae adults rapidly increase body temperature when exposed to radiatio n and suggest that the species' characteristic flight within plant can opies is a thermoregulatory behavior to prevent overheating.