The brown marmorated stinkbug is an invasive that appears to have been imported from China in the late 1990s. It has spread rather quickly and done such extensive damage that the financial newspaper The Economist ran an article about it in October, 2011.
1/2 - 3/4"
The stinkbug damages plants by sucking its juices out of the leaves, stems or fruit.
These bugs are large enough that they can be pulled off and smashed. However, if a spray is desired NEEM or other agricultural oils should work.