Timing of Daily Activities in Adult Lepidoptera
A survey is presented of the daily timing of eclosion, flight activity [Ac], foraging, mating and ovipositing in adult butterflies and moths. Typically, nocturnal moths emerge from the pupal case in the afternoon and early evening, forage and deposit the eggs in the first part of the night, and mate during the second part. Diurnal moths and butterflies emerge in the morning, and forage and mate during the day whenever temperatures [T] are favourable. Their Ac is dependent on their ability to thermoregulate behaviorally. Some moths can be active both by day and night, changing from a nocturnal to a diurnal pattern when T are too low at night, or they mate during the day, perhaps as a reproductive isolating mechanism. The timing of the Ac are adaptations to ultimate ecological factors, some of which are discussed. The timing is also controlled by circadian rhythms, normally entrained by the light-to-dark transition in moths, and by the dark-to-light transition in butterflies. The emergence rhythm seems to be controlled by both transitions. The Ac rhythms can be phase shifted by T changes, and the phase position differs in different constant T.