According to the Pacific Northwest Insect Management Handbook, "There are currently no established treatment thresholds for brown marmorated stink bug, but given the severity of damage that occurs when populations are noticeable, growers readily spray insecticides. Current insecticide programs in the eastern USA are based upon pyrethroid, carbamate, organophosphorus and nicotinoid insecticides.  All of these insecticides are disruptive to various natural enemies and have the potential to cause secondary pest outbreaks. Gardeners and growers with small plots may be able to exclude BMSB with fine netting, but this is not feasible for larger farms."
http://insect.pnwhandbooks.org/pnw-insect-management-handbook/emerging-pest-brown-marmorated-stink-b…

A few years back Penn State did several efficacy trials with various insecticide programs and found a few programs that were effective (usually with multiple applications). For more information, see the following: http://extension.psu.edu/plants/tree-fruit/news/2012/management-options-against-brown-marmorated-sti...

Good luck!