72 Microseasons of the Pacific Northwest

Each June, the major rivers draining the eastern Cascades — the Yakima, the Methow, the Wenatchee, the Naches, and the North Fork of the Snoqualmie — host some of the most extraordinary aquatic insect hatches in North America. Golden stoneflies (Calineuria californica) and the enormous, orange-bodied salmonflies (Pteronarcys californica) emerge from the gravel beds where they have spent two to four years as nymphs, crawling to shore and splitting their shucks to emerge as winged adults. On the Yakima River, this hatch is one of the most anticipated events of the fly fishing calendar. The salmonfly is hard to miss: adults are nearly two inches long with orange-and-black wings, and they cling to streamside willows, alders, and boulders in numbers that can carpet rock surfaces. In flight, they are clumsy and heavy, falling onto the water's surface — and the trout below take notice. Wild rainbow and brown trout that have been feeding on tiny midges and nymphs all winter will rise aggressively to adult salmonflies drifting on the surface, their splashing takes audible from the riverbank. Pale morning dun mayflies (Ephemerella spp.) and golden stones hatch simultaneously, extending the surface feeding window through morning and evening. Beyond the fishing, the hatch is ecologically fascinating: dippers (Cinclus mexicanus) hunt nymphs in the rushing shallows; canyon wrens sing from the basalt cliffs above; mergansers and harlequin ducks feed in the riffles. The Yakima Canyon Scenic Byway between Ellensburg and Selah offers paved road access to miles of river, with pullouts for watching rises and insect activity from shore. The Methow River and the lower Wenatchee are equally productive. West-side observers can witness a smaller but similar hatch on the upper Skykomish and the North Fork of the Snoqualmie by mid-June.