Does flight morphology relate to flight performance?: An experimental test with the butterfly Pararge aegeria

1. The relationship between maximal acceleration capacity and flight morphology was tested experimentally in the butterfly Pararge aegeria . Such relations are often assumed but seldom tested. 2. In both sexes acceleration capacity was positively correlated with total body mass, thorax mass, forewing area, forewing length, wing loading, aspect ratio and centre of forewing area (centroid). Relationships with total body mass, forewing area, forewing length and wing loading were stronger in males. This can be explained by different mass allocation: males allocate proportionally more mass to the thorax, females more to the abdomen. 3. Evidence for the combined effect of morphological traits on acceleration capacity was found by multivariate analysis. In males and females, a more distant relative centroid and higher relative thorax mass were related to a higher flight capacity. In addition, aspect ratio was positively related to acceleration capacity in males only. 4. Our results support the assumed mechanism behind the relationship between flight morphology and mate-locating behaviour.