For the first time since it hitched a ride from Asia to Allentown, Pa., in 1998 and went on to invade 44 states and four Canadian provinces, the government is cautiously optimistic that it is winning the war against the brown marmorated stink bug.

“Yeah, it is good news. It’s pretty good,” said Tracy C. Leskey, the key Agriculture Department research leader on stink bugs and other invasive pests.