When Trout Eat Foam: The Dry Fly Rig Every Angler Should Be Using Right Now

It was August, high sun overhead, and I was standing knee-deep in a shaded riffle somewhere in the Sierra foothills. A breeze rustled through the dry grass above the riverbank, and just loud enough to hear—click click click—a grasshopper launched itself into the air like it had big dreams. Those dreams ended about three feet later when it cartwheeled straight into the river and started kicking furiously. A second later, the surface exploded. One leap, one splash, and that hopper was gone—sucked under by a trout who probably thought it had hit the jackpot.

That’s hopper fishing. And that’s exactly why this time of year turns normally sane anglers into foam-addicted dry fly junkies.

If you’ve never fished a hopper-dropper rig before—or never even heard of one—this post is for you. And if you have, but still aren’t sure how, when, or where to fish it in northern California, we’re about to change that too.

What Is a Hopper-Dropper Rig?

At its core, a hopper-dropper setup is simple: one big dry fly, usually a foam grasshopper, floats on top. A small nymph, like a beadhead or emerger pattern, hangs below it on a short piece of tippet.

The dry fly imitates a real grasshopper (or just something big and edible-looking), while the nymph represents whatever else might be tumbling through the current—mayfly nymphs, caddis, drowned ants, you name it. The dry fly acts like a strike indicator, but with one major upgrade: fish actually eat it.

The result? You get the best of both worlds

The result? You get the best of both worlds. Topwater takes and subsurface action. Twice the chances. Twice the fun.

The Grasshopper Life Cycle. (and Why Trout Care)

Unlike aquatic insects that hatch in the water, grasshoppers begin life as eggs in the soil. These eggs hatch in late spring, and the nymphs grow throughout summer—molting several times until they reach full size. Once they develop wings, things get interesting.

Hoppers can fly, but not well. They’re clumsy, light-sensitive, and notoriously bad at navigating wind. Which means, when conditions are right—hot days, dry grass, and a decent breeze—they end up in the river. A lot.

Trout learn this quickly. After a few clumsy bugs belly-flop into the current, fish start watching the banks and taking up prime feeding positions. That’s your cue.

Hopper Season by Region (But Especially NorCal)

Across the western U.S., hopper season varies based on elevation, latitude, and local conditions:

• Rocky Mountains: Hoppers start showing up in late June or early July.

• Pacific Northwest and higher elevations: Mid-to-late July.

• Midwest and Eastern U.S.: August into September, but often with fewer trout rivers suitable for hopper fishing.

But in northern California, we hit that beautiful sweet spot. Our hopper season typically kicks off in late July and peaks through August into early September, depending on elevation and how long the heat sticks around.

Our hopper season typically kicks off in late July and peaks through August into early September

The Yuba River is a prime example. Wide, rocky, with lots of open-bank terrain and abundant grasses, it’s tailor-made for hopper-dropper setups. The wild trout in the Yuba don’t mess around—when they eat a hopper, they commit. While I’m not currently guiding that river, I still consider it one of the best hopper fisheries in the state. And if you’re willing to walk and watch, there are plenty of small water options tucked into the foothills and mountains that produce similar eats.

Best Water for Hopper-Dropper Rigs

While the technique is widely versatile, some water types excel:

• Bankside Seams: Look for undercut banks, grassy edges, or steep drop-offs next to vegetation. Hoppers tumble off these areas all the time.

• Pocket Water: Great spots to land a hopper and let it bounce around naturally, with a dropper drifting in the adjacent current.

• Riffles and Glides: Trout tuck into transition zones and actively feed in medium-speed water

Pro tip: even in technical tailwaters, this rig can get results. Just keep your profile low and your casts tight.

Hopper-Dropper Rigging Tips

A few tricks that make a big difference:

• Tippet Length: Start with 18–24 inches from hopper to dropper. Adjust depending on water depth.

• Tippet Size: 4X or 5X usually works well. Just make sure your hopper has enough buoyancy to float the rig.

• Foam is Your Friend: Foam-bodied hoppers stay afloat longer, even after repeated takes. Chubby Chernobyls, Fat Alberts, and smaller micro hoppers are all great choices.

• Droppers: Tie on beadhead pheasant tails, Frenchies, small caddis pupa, or even drowned ants and beetles.

You’ll want to watch the hopper closely—it tells you everything you need to know. If it twitches, stops, or disappears? Set the hook.

When You’re Ready to Fish It Right

This isn’t just a “nice to try” tactic—it’s one of the most productive, visual, and fun methods you can use during late summer. It teaches you how to read water, control your drift, and react to subtle takes—all while giving you a shot at those thrilling topwater eats.

If you’re curious but not quite confident, that’s where I come in. Whether you’re new to fly fishing or just looking to improve your dry-dropper game, my Introduction to Fly Fishing Clinic is the perfect place to start. I’ll teach you how to rig it, cast it, fish it, and read the water so you can do it all on your own—whether it’s on a creek, a tailwater, or a freestone river.

And if you’re looking for a private day on the water tailored to your goals, I offer that too.

Every cast is an adventure. Let’s make yours count.

Visit bockflyfishing.com to learn more, book your spot, or reach out with questions.

Ready to Make the Cast?

If you’re feeling that tug—yeah, that one deep in your gut—you’re not alone. Whether it’s wild fish testing your patience Or a steelhead peeling line and breaking hearts, this story’s best told waist-deep in moving water.

• Book a trip – Come chase trout and steelhead or Shad with me, and Feel The Tug for yourself.

• Join the mailing list – Get honest fishing reports, hatch updates, and tips that actually help.

• Check out our clinics and resources – From first casts to advanced tactics, we’re here to make you a better angler.

Because every cast is a choice—and when you understand what’s on the other end of your line, it matters even more.