How do butterflies help in reproduction of plants?

Butterflies go from flower to flower to collect there food. In this process pollen grains are attached to there body and then they are transferred to next flower. It is not necessary that, they will visit the same variety of plant. But then, they carry large number of pollen grain on there body and appropriate one fertilize the ovum and new fruit containing seeds is there to carry forward the Genetic information to next generation. So without plants butterflies will die and without butterflies plants will die.(GOD is great !)