Two Green Shield Bugs

Two Green Shield Bugs

Observation - Two Green Shield Bugs - UK and Ireland. Description: Two Green Shield Bugs in Broadbridge Heath, west Sussex in March 2012. Can someone please explain why the darker shield bug had vibrating antennae and why they are differrent colours?

Two Green Shield Bugs in Broadbridge Heath, west Sussex in March 2012. Can someone please explain why the darker shield bug had vibrating antennae and why they are differrent colours?