Summary1. The spatial arrangement of resources and climatically favourable sites affects the dispersal pattern of butterflies.2. The microdistribution of the satyrine butterfly Lethe diana changes seasonally, meaning that the relative spatial arrangement of resources also changes seasonally. The seasonal change in the dispersal pattern of this butterfly was studied.3. Males of the May–June generation tended to stay in a restricted habitat patch while females of the same generation did not. A number of the May–June generation males became resident at prime forest edge sites, where a territorial behaviour that was rarely seen in other generations was prevalent. Females of the May–June generation moved to these territorial sites for mating but left after copulation to avoid male harassment; their residency was therefore weak.4. In both sexes, the July–August generation tended to be more mobile than the September–October generation. This was because the July–August generation butterflies utilised dark environments for thermoregulation and, because these conditions were widespread throughout the forest, the butterflies were able to move widely. The September–October generation, however, preferred intermediate light conditions, which tended to be restricted to the forest edge; as this was a relatively small area, butterfly movement was restricted.

To assess bird predation pressure on butterflies, I investigated beak marks on the wings of two Lethe butterflies for 3 years in secondary temperate forests. If bird predation had significant effects on average longevity of butterflies, and if the number of specimens preyed upon was proportionate to the number of beak-marked specimens, the beak mark frequency would be negatively correlated with average longevity of a butterfly. Bird predation pressure is generally thought to influence average longevity of butterflies. Therefore, if there is a negative correlation between beak mark frequency and average longevity, bird predation pressure would be reflected in beak mark frequency. Beak mark frequency was negatively correlated with longevity in Lethe diana (Butler), the more abundant of the two species; thus, the beak mark frequency was considered to be a suitable index of bird predation pressure on the butterflies investigated in this study. In both Lethe species, beak mark frequency was higher in females than in males. Because female butterflies have a relatively smaller thorax and flight muscles and a larger abdomen that contains eggs, they are presumably weaker or less agile fliers than males, and are probably attacked more easily by birds. In autumn, butterflies were heavily attacked by birds irrespective of sex and species. Because the numbers of lepidopteran larvae, which are the preferred prey of many birds, decreased in autumn, birds were thought to shift their diets to alternative prey such as adult butterflies.

Abstract. Males of the small copper butterfly, Lycaena phlaeas daimio, exhibit two mate-locating tactics: patrolling and perching. Field investigations were conducted to determine the biotic and abiotic factors affecting the mate-locating behaviour of male L. phlaeas. Patrolling was often observed when light intensity was high. Perching was performed throughout the day regardless of environmental conditions, but the chasing of passing insects increased at high light intensities. The activity patterns of the males were not affected by those of the females. The thoracic temperatures of patrolling males were lower than those of perching males under cool conditions, suggesting that patrolling males lose heat more easily. In contrast, perching males may more easily regulate their body temperature to a suitable level as they fly for shorter periods and can bask while waiting for mates. These results highlight several reasons (i.e., heat loss, energetic costs) why males patrol when weather conditions are favourable.

The territorial behaviour of butterflies often changes with temperature. The satyrine butterfly Lethe diana has three generations a year, and males display territorial behaviour in the May-June and September-October generations, but not in the July-August generation. This study investigated the relationship between this seasonal change in mate-locating behaviour and thermoregulation. When L. diana was able to hold a territory, thoracic temperature ranged from 23.8 to 33.6 ° C. This temperature was mainly influenced by environmental temperature based on air temperature, solar radiation, and wind, and metabolic heat was estimated to increase thoracic temperature by about 5 ° C in the May-June generation. When environmental temperature at a territorial site was within this range of the thoracic temperature minus the metabolic heat (approximately 5 ° C), L. diana males held territories. Since territorial sites were selected irrespective of the temperature, L. diana could not hold a territory when the temperature of the territorial site exceeded the threshold. In July-August, the temperature of the territorial site was almost always above the suitable range. These results suggest that seasonal change in territoriality of L. diana is due to behavioural thermoregulation.

Many folivorous insects sever leaf veins, trench across leaf blades, or girdle petioles prior to feeding on leaves. The purpose of these behaviours is generally thought to be sabotage of the anti‐herbivore chemical defences of host plants. For insects that construct leaf shelters, these behaviours may make leaves easier to roll or fold. Larvae of the Indian red admiral butterfly, Vanessa indica (Herbst), cut trenches at the base of host plant leaves and construct leaf‐fold shelters. I attempted to determine which of the above functions the trenching behaviour of V. indica larvae serves. If the function of trenching is to facilitate leaf‐folding, then larvae should cut trenches before folding leaves. When the larvae used larger leaves, they tended to trench them prior to folding them. This suggests that the function of trenching behaviour is to make leaves easier to fold. However, larvae sometimes cut trenches after folding the leaves, suggesting that this behaviour has additional functions. When the larvae were about to moult or pupate, they did not cut trenches, suggesting that trenching behaviour may also be involved in feeding.