Q: What in the heck is going on with these poison ivy leaves? They look to be covered with warts.
A: The warts are caused by gall-making eryophid mites. These tiny creatures wound the leaf and insert eggs. Leaf tissue grows around them in these characteristic forms.
I added a new word to my vocabulary recently: a cecidologist is one who studies galls on plants.
The infestation doesn’t hurt the leaves. I wish it did….the world might be a better place with a few less poison ivy plants!