They flap their wings quite slowly, usually from 5-20 beats per second. In contrast, some flies beat their wings as fast as 1000 times per second. The slower ones flutter about at only a few km per hour. The adult butterfly, after emerging from the pupa, does not grow. Only a few butterflies fly at night, but many moths fly during the day.
Caterpillars destroy millions of dollars worth of crops each year.
The caterpillar of the white cabbage butterfly is one of the most destructive, eating leafy vegetables, especially cabbage. Butterflies, on the other hand, drink only nectar and will carry pollen from flower to flower. This cross pollination of flowers is important in the production of fruit and seeds. Some butterflies migrate each year. The monarch may fly as far as southern Canada in the summer and retreat to the highlands of Mexico in the winter.