Why butterflies are dying in Chennai?!

Dead butterflies inside Anna University 

Chennai: Every day when I am on my way to university , I used to see lot of butterflies. This sight makes my day more joyful. I have seen so many various types of butterflies  everywhere inside the campus. And I also love taking snaps and videos whenever its possible. But unfortunately, lately I have been seeing  alot of dead butterflies. I want to make some awareness to safe  these beautiful creatures so I have taken some pictures and have posted it. The question is, how to safe them ?? And who is to blame for it. Is it nature  or Ourself?