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Mobility is a key factor determining lepidopteran species responses to environmental change. However, direct multispecies comparisons of mobility are rare and empirical comparisons between butterflies and moths have not been previously conducted. Here, we compared mobility between butterflies and diurnal moths and studied species traits affecting butterfly mobility. We experimentally marked and released 2011 butterfly and 2367 moth individuals belonging to 32 and 28 species, respectively, in a 25 m × 25 m release area within an 11-ha, 8-year-old set-aside field. Distance moved and emigration rate from the release habitat were recorded by species. The release experiment produced directly comparable mobility data in 18 butterfly and 9 moth species with almost 500 individuals recaptured. Butterflies were found more mobile than geometroid moths in terms of both distance moved (mean 315 m vs. 63 m, respectively) and emigration rate (mean 54% vs. 17%, respectively). Release habitat suitability had a strong effect on emigration rate and distance moved, because butterflies tended to leave the set-aside, if it was not suitable for breeding. In addition, emigration rate and distance moved increased significantly with increasing body size. When phylogenetic relatedness among species was included in the analyses, the significant effect of body size disappeared, but habitat suitability remained significant for distance moved. The higher mobility of butterflies than geometroid moths can largely be explained by morphological differences, as butterflies are more robust fliers. The important role of release habitat suitability in butterfly mobility was expected, but seems not to have been empirically documented before. The observed positive correlation between butterfly size and mobility is in agreement with our previous findings on butterfly colonization speed in a long-term set-aside experiment and recent meta-analyses on butterfly mobility.

1. Mitigation tools aimed at counteracting the loss of farmland insect diversity and associated ecosystem services are usually conducted on cultivated fields. Possibilities of managing field-forest ecotones for biodiversity have been rarely discussed, despite their importance for flower-visiting insects.2. The effectiveness of logging in enhancing three aspects of insect diversity (bumblebee abundance, total species richness, and habitat specialist butterfly abundance) and changes in insect community composition were studied in a three-year field experiment. The study included 15 field-forest ecotones, each with a 50 m long and 25 m wide treated area and a corresponding control. At forest edge, a 5 m wide strip was clear-cut and behind this strip, a 20 m wide belt was thinned to a basal area of 8 m 2 ha À1 .3. Logging simultaneously promoted all three aspects of insect diversity. Changes were more apparent at clear-cut edge than in the thinned interior. Community composition changed via increased abundance of open habitat species, especially butterflies. 4. Logging promoted warm microclimates and flower availability at clear-cut edges. All three aspects of insect diversity showed a positive response to flower coverage, which in turn was negatively correlated with the amount of logging residue.5. Creating open field-forest ecotones is beneficial for flower-visiting insects and open habitat species in particular. This approach is expected to be most beneficial at sunny forest edges and sites which become overgrown slowly. In addition, we suggest logging residue to be removed when aiming to promote flower-visitors.

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