Preferences for nectar sugars in the peacock butterfly, Inachis io

1. Peacock butterflies, Inachis io , were tested experimentally for their preferences for nectar sugars.
2. In tests with different plain sugar solutions (25%, weight to total weight) the butterflies strongly preferred sucrose and fructose over glucose. They also preferred sucrose over fructose.
3. In tests with mixed sugar solutions the butterflies clearly preferred both sucrose-dominant (sucrose : hexoses = 5 : 1) and balanced sugar solutions (sucrose : glucose : fructose = 1 : 1 : 1) over hexose-dominant sugar solutions (sucrose : hexoses = 1 : 5).
4. Females consumed significantly more of the balanced sugar solution than did males.
5. These results are discussed with respect to previous experiments on nectar preferences of butterflies, nectar sugar composition of butterfly-pollinated flowers, and flower preferences, physiological and reproductive aspects of butterflies.