Mayfly Nymph Colorado Fly Supply Sale! from $1.65 Size 14 16 18 Qty. Add to Cart This item is currently on backorder but you can still purchase it now and we'll ship as soon as more become available. A great mayfly nymph/baetis imitation that works well year-round. Drop down to the smaller sizes in very early spring and late fall/winter. SKU: BHMAYFLYNYMPH14 Tweet