Last Saturday we visited Cunningham Falls State Park near Frederick, Maryland. It was foggy and drizzly and there were big millipedes everywhere.
This is Narceus americanus, a native and common inhabitant of the woods around here. The ones on the fallen trunks seemed to have been eating the stuff growing on the rotting wood. Here is a close-up of the head of one. Note the compound eyes.
I thought the weather was also perfect for gastropods, but after more than an hour of looking all I could find was one slug.