Rates of nectar feeding in butterflies: effects of sex, size, age and nectar concentration

Rates of ingestion of sucrose varied with sucrose concentration and butterfly sex, age and size for Speyeria mormonia Edwards (Lepidoptera: Nymphalidae). Peak rates of ingestion occurred between sucrose concentrations of 30% and 40%, as predicted by previous theory. Males fed at a faster rate than did females under most experimental conditions. Rates were also high for medium to large individuals as opposed to small individuals. Ingestion rates decreased with age for males but not for females. These results are compared with data available for other species and considered in the context of information on nectar concentrations and composition in the field and activity budgets for S. mormonia. Finally, the possible impact on plant-pollinator interactions is evaluated.