Stillwater nymphs can be anything from brown to yellow to black to red. Olive, tan and brown are your most common. I like this as a general searcher pattern when fish won't take my usual assortment of leeches, scuds, chironomids and dragons. It's simply a marabou feather tied in as a tail and wrapped forward on a size 10 hook. Looks like any type of bug. Mayfly, damsel, leech, whatever. It works