I analyse the effects of habitat fragmentation on the pollination success of a perennial, butterfly‐pollinated, caryophyllaceous herb, the maiden pink, Dianthus deltoides L. The study was conducted in July 1986 and July 1987 at two different sites in southwest Sweden, an undisturbed “mainland” site and a fragmented site consisting of “habitat islands” within a heavily utilized agricultural area The fragmented area had a lower diversity and abundance of both flowering plants and flower‐visiting insects. Dianthus flowers received fewer visits in the fragmented area than in the mainland area, and the seed set was much lower. Hand pollination increased seed set up to 4.1 times in the fragmented area, but no significant differences were found between hand‐pollinated and control flowers at the mainland site. There were no differences between the two sites in standing crop of nectar, ovule number per flowers, or seed set of bagged flowers, band‐pollinated flowers, and hand‐pollinated fertilized flowers Thus, the difference in natural seed set between the two sites can be explained by differences in pollinator service.

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Nectar plant utilization by butterflies was compared with the abundance of flowering plants on some SW Swedish meadows. The transportation of pollen grains by individual butterflies was analysed using a scanning electron microscope.For the majority of plant species, butteflies were of minor importance as pollinators. Some flowers with protruding sexual organs, e.g. Knautia arvensis, when heavily utilized by butterflies, might also be pollinated by these.For Dianthus deltoides and Viscaria vulgaris, butterfly pollination was found to be important.Several butterfly species, e.g. Plebicula amanda, visited legumes regularly. In spite of this, legume pollen was rarely transported by the butterflies. This suggests these butterflies act as nectar robbers among the legumes.