Annectotal story....
Happened to me this summer....
While approaching our hub airport, a tiny weak blob of green on the radar between us and the airport (inside 10 miles). No moisture in the area. Played with tilt and gain....still there.
As we met the "blob".....splat, splat, splat.....one of the forward windshields was virtually covered in "goo"....
Cicada's
Cicada - Wikipedia, the free encyclopedia a huge swarm.
Our arrival mechanic told us numerous aircraft had arrived with this gooey mess on the windshileds and leading edges that night.