Grasshoppers do not hatch. They live in the grass along the river and end up in the water by accident: blown in by the afternoon wind, knocked in by a bad jump, or washed off a bank. That is why the 37 river charts on this site with a hopper line all peak in July and August, a few running into September, and why hopper fishing follows the weather more than the calendar. Hot, windy, late-summer afternoons on a river with grassy banks are hopper conditions. A cool, still morning is not, even in the middle of August.
Which grasshoppers, and why size matters less than you think
The hoppers trout eat are mostly short-horned grasshoppers, family Acrididae, order Orthoptera. Dozens of species live along Western rivers, and they range from a size 14 in early July, when the year's nymphs are still small, to a size 6 by September. Colors run tan, yellow, olive, and gray-brown, and most have a yellow or cream underside, which is what the fish sees. The river pages here list hoppers in 8 to 12, a reasonable summer average, but the honest rule is to look at the grass. Walk the bank and see what jumps. Match that, and go a size smaller when fish are refusing.
Wind, heat, and the afternoon
Hoppers get active when the day warms. They start jumping in the late morning and are busiest in the heat of the afternoon, which is also when the wind comes up in most Western river valleys. Every gust puts a few in the water. Trout learn this within a couple of weeks, and by late July a fish under a grassy cutbank on the Yellowstone or the South Fork of the Snake is watching the bank as much as the drift. The best hopper days are hot, bright, and blowing, and the best hours run from early afternoon into evening. On a still morning, fish something else and come back when the wind starts.
Where the hoppers are is as important as when. They live in dry grass and hay, so the productive water is the bank below a meadow or a hayfield, not the bank below a rock wall or timber. On the Madison or Big Hole the hopper fishing is concentrated on the ranch stretches, and a float through irrigated hay meadows is worth more than one through a canyon.
How a trout eats a hopper
A hopper hits the water with a splat and struggles. Trout hear and see that, and often take the fly with a slashing rise that is easy to set on. But big fish that have been fooled a few times take differently: they follow, drift back under the fly, and sip it with a slow open mouth. Wait a beat on the set. A short twitch that moves the fly an inch triggers the followers, and so can drag at the end of the drift. This is one of the few dry-fly situations where movement helps.
The hopper-dropper
The most productive summer rig on the rivers listed here is a foam hopper with a nymph hanging below it. The hopper floats the nymph and acts as the indicator; the nymph catches the fish that look at the hopper and do not commit, which on most days is most of them. The Green page lists a Parachute Hopper in 10-12 alongside a Foam Beetle and an ant for exactly this kind of afternoon. Set the dropper at eighteen inches to three feet, use a beadhead so it sinks fast, and set on any movement of the hopper, because the nymph take is quiet. Fish the rig a foot off the grass and let it drift along the bank rather than across the current.
The rivers here and when they peak
The 37 hopper rivers fall into two groups. Thirty-two peak in July and August: the Montana freestones (Big Hole, Blackfoot, Clark Fork, Gallatin, Madison, Rock Creek, South Fork Flathead), the Yellowstone Park rivers (Lamar, Gibbon, Firehole), the Wyoming tailwaters (North Platte, Green, Shoshone), the Idaho freestones (Salmon, Lochsa, Big Wood), the Colorado rivers (Colorado, Roaring Fork, Poudre), the Utah mountain and desert streams (Bear, Duchesne, Fremont, Sevier, East Fork Sevier, Price, Uinta, Lake Fork, Upper Provo), the New Mexico streams (Pecos, Red, Rio Grande), and Arizona's Black River.
Five run July through September, the ones with the biggest hay meadows and the longest warm falls: the Yellowstone, the Bitterroot, the South Fork of the Snake, the Snake in Wyoming, and the New Fork. September there is often better than August: the bugs are biggest and the first frosts slow them down.
Patterns from the river pages
- Chubby Chernobyl #8-10, listed on 35 rivers. Foam body, rubber legs, a white wing you can see at fifty feet. Not a realistic hopper, but it floats a heavy dropper all day.
- Dave's Hopper #10-12, listed on 35 rivers. The traditional deer-hair and turkey-wing hopper. Lower floating, more realistic, better for fish that have refused foam.
- Rainy's Grand Hopper #8-10, on the Madison, the South Fork Snake, the Snake in Wyoming, and the Duchesne, a big foam pattern for September.
- Parachute Hopper #10-12, on the Green, a middle option that floats well and looks like the bug.
Carry tan and yellow in each, plus a 12 or 14 for July and for spring creeks like Silver Creek where a size 8 foam fly gets refused.
A hopper afternoon, start to finish
Get on the water around noon. Rig a Chubby with a beadhead Pheasant Tail or Prince two feet below on 3X or 4X. Fish downstream along the grassy bank, casting a foot from the edge and letting the fly drift the length of the undercut. Twitch it once. When the wind comes up, fish the bank it is blowing toward, because that is where the hoppers are landing. Switch to a Dave's Hopper alone if fish are refusing the foam. Fish until dark. Check the state fish and game agency for float and access rules, and the gauge on the river page, since a late-summer thunderstorm can muddy a freestone for a day. And if you see winged ants in the air, stop and read the flying ant page, because the fish will drop hoppers for ants every time.