Helicopter - a Bell 210, I believe - turned overhead and returned west while I was looking for butterflies in the pasture. We see a lot of helos here as training flights routinely come from the Pennsylvania National Guard reservation at Fort Indiantown Gap near Harrisburg and occasionally from Willow Grove Naval Air Station near Philadelphia, as well as the state police looking for speeders on I-78 and medevac flights heading to the trauma center at Lehigh Valley Hospital Center outside Allentown.