Here's the story: A spiny witch hazel gall aphid (Hamamelistes spinosus) was born on a river birch leaf in or near Frick Park in the spring of 2009. She sucked on the leaf and pumped out offspring asexually. A few months later, her great grandchildren mated and the females flew away, looking for a witch hazel. They laid their eggs on a witch hazel twig, and the eggs didn't hatch until spring of 2010. The baby aphids started sucking on flower buds, and a gall grew around each one. By late summer the galls were full-grown and each mama aphid had raised a brood of winged aphids, which flew off to look for a river birch. Then the galls hung on the branch until I found them this week.
about 4 mm long. Found on the underside of a hackberry leaf in Frick Park. I was inspired to look for these by Charley Eisman:
Thanks to Ray Gagne for identifying the specimen to species.
cap color ranged from bright orange, like this, to brown, like in the following picture.
apple snail egg mass