SEASONAL-VARIATION IN MATE-LOCATING ACTIVITY IN THE DESERT HACKBERRY-BUTTERFLY (ASTEROCAMPA-LEILIA, LEPIDOPTERA, NYMPHALIDAE)

Males of the desert hackberry butterfly occupy and defend encounter si tes used in mate location. This activity is restricted to about 3 h ea ch day, usually between 0800 and 1100. We monitored daily and seasonal changes in the number of males perched at encounter sites along a cen sus route on 32 days during 1991 and 1992. The results indicate that m ales are active earlier in the mornings during summer than in spring o r fall. However, they were not active at all rimes when air temperatur e and solar altitude would appear to permit perch site occupation. Dai ly and seasonal shifts in air temperature and solar radiation are not a sufficient proximate explanation for patterns of male behavior. Over a wide range of temperatures, females most often eclose around 0800, which suggests that the timing of female availability determines when males are active within the broad limits imposed by thermoregulatory r equirements.