The Black Wooly Bugger is an incredibly diverse fly that imitates a wide variety of trout food, these can include: dragonflies, damsels, leeches, etc. Leech Patterns have proven to be especially effective in the evenings. The early spring, and late fall are also times where the leech excels as the trout are skimming in the shallower waters. They essentially just depict an edible treat. The Black Woolly Bugger has demonstrated time and time again that it is more than capable at saving a rather difficult fishing session.