At about 6:30 pm on the evening of 9/12 I saw a huge, thick swarm (1,000s) of large (I believe Green Darner, which are migrating now) dragonflies along a stretch of over 5 miles along Clarkesburg Road (MD 121) heading north from before Lewisdale Road to beyond Bethesda Church Road. They were indeed accompanied by dozens of Nighthawks actively feeding, presumably on the dragonflies. I wonder if the Nighthawks follow the migration of the Green Darners as a ready food source? I was on my way to a speaking engagement so I could not stop to observe more closely. Frustrating!