This is a late instar (stage) green stink bug nymph.
The green stink bug adult and nymphs feed on plant juices including leaves, fruits, flowers, and seeds. When they feed on fruit or seeds they can be considered a garden pest.
There are 5 stages of nymph development until they turn into the plain green adult. There are 2 generations in the south and one in the north.
These stink bugs are found in most of North America in gardens, meadows, cultivated areas, as well as woodland edges.
Here are photos of adults and nymphs -
http://bugguide.net/node/view/9066/bgimage
