Hatch timing and insect activity
A helpful guide for when to expect hatch activity and effective pattern selection.
Western Region (California, Colorado, Idaho, Montana, Oregon, Utah, Washington, Wyoming,)
Small Winter Stones
The willow, needle and other small winter stoneflies can hatch when there is snow on the ground. Though the adults are rarely important to the trout, small dark stonefly nymphs are readily available and often end up on the menu.
Large Stonefly Nymphs
The big stoneflies are available almost all year long. In the early season focus on using smaller sizes and as the main hatch nears use larger sizes. The timing for the need of large sizes often occurs during the higher water of spring so get the big beaded version and get down.
Many western rivers have a midge hatch in late March to early april that are about 1/2 inch in length. Some early season dry fly activity can be had not to mention some very nice nymphing.