Thanks to meteorologist @jefflast for pointing us to the phenomenon of lake flies hatching over Lake Winnebago. And thank you to the fine folks at National Oceanic and Atmospheric Administration for this 2009 animation showing us instead of telling us: there are a lot of these flies.
"Millions...potentially trillions." You can read more about the hatch on the noaa.gov site here.
At long last it is (somewhat consistently) warmer and over half the trees are leafing out. I look forward to discovering new flora and fauna as we head into our first full Wisconsin summer.