It must be almost June, because these little beetles we saw everywhere today near Putah Creek are called June Bugs or June Beetles.
and then this striking black & red caterpillar, this guy was really on the move, maybe it wasn't too comfortable sporting those bright colors hanging out in the open with all the little swallows, robins and bluebirds flying around. I googled it and think this guy is a Pipevine Swallowtail caterpillar.
Here is a nice link to learn more about the Pipevine Swallowtail (it's a beautiful butterfly). The site explains how a caterpillar of this size is likely poisonous to predators. But still it would be a really bad day to get pinched in half, by a bird, then dropped from the sky when you taste bad.