by Marlene Berlin
First, I noticed these black patches under trees.
Then a neighbor who was walking her dog on Soapstone trail pointed out the branches above these spots were covered in something white.
It was only happening on beech trees, and we both wondered what it could be. I called Bill Yeaman, a natural resource specialist at Rock Creek Park. He told me that the white spots were the woolly beech aphid, and it is not harmful to the beech trees. The other name for this critter is the boogie woogie aphid, because when threatened, “they’ll lift their fuzzy posteriors high in the air and pulse them in unison as a warning to predators.”
And those black patches on the ground? Yeaman explained that they are from the mold that grows on the aphid droppings.