There are many leaf-based galls on a willow tree. Photos 7-13 show the underside of the leaf. Photo 19 show an insect on one of the galls.
Host plant: https://www.inaturalist.org/observations/215860465
An insect on it: https://www.inaturalist.org/observations/217804035
Photos 2-11 were edited to have a Custom White Balance in Photoshop (Photoshop's preset).
Photos 2-6 were brightened.
I saw a lot of these while I was hiking. Just wondering what it is called.
Incredible shade of red this aphid gall creates...
and convoluted gall on Valley Oak, Quercus lobata