If memory serves, and it often does not, forest hives are white with a dark green/grayish stripe. They typically hide up in the trees and in my experience are always the last hive I find and the one I want the most.
It can help to run around during the night since they do produce light, but in my experience the lighting is typically glitched and as such they are pretty well hidden.
Meadows are red, rocky is grey and blend in really well with their smooth stone surroundings, and water is blue.