Can anyone identify this insect from India?
This is definitely a bug - as indicated by the characteristic body form and the segmented (it should be five) antenna. My guess here is that this is Nezara viridula, also known as the "southern green stink bug" or the "southern green shield bug". 

See this image (from here):



Besides being a pest for agriculture, they are harmless and not toxic, although they can spread a stinking substance when threatened, hence their name. You can find more about them here and here.