Appias libythea olferna (Striped Albatross) Butterfly

This black and white striped butterfly was found in the Miri house garden. 
In fact, to my surprise, this time there were so many of them flying around on the tall grass. Why?

I found two trees with a lot of green berries at the back garden where the butterflies actually lived. Most of the leaves had been eaten by the larvae with many holes! There were many types of butterflies hovering on these trees!