Another landmark

Last night ... in New York City's
Central Park, in the dark, a spark ...

this year's first
Lightning Bug.

--Kentaurian --

PS -- "Last night" was Saturday June 18.
Lightning bugs are also known as fireflies. As you may know they are beetles, not flies. The species found in Central Park is  Photuris pennsylvanicus. 

PPS About the flashing light on lightning bugs: It's on the end of the abdomen. The females are wingless and flash from the ground. The males fly around trying to locate the females. So if you see a firefly flying, it's a guy firefly.