Chubby Chernobyl
A modern foam attractor pattern that has become a Montana staple. Virtually unsinkable, the Chubby floats heavy nymph droppers and draws aggressive strikes from trout looking for a large, easy meal. Available in numerous colors. The Chubby Chernobyl represents the evolution of the foam hopper and stonefly genre. Its layered foam body creates a nearly indestructible fly that requires no floatant and rides high on even the roughest water. The rubber legs provide enticing movement, and the flash wing catches light in a way that grabs attention from trout holding deep. Whether tied in tan, purple, pink, or any other color, the Chubby simply produces fish. Montana guides have embraced the Chubby Chernobyl as their go-to dry-dropper indicator fly, and for good reason. It supports one or even two heavy nymphs without sinking, it is visible at long distances, and trout eat it with startling aggression. On the Madison, Yellowstone, and Gallatin rivers, more fish are likely caught with a Chubby on top than any other dry fly. Its effectiveness extends from early July through October, covering the heart of Montana's fishing season.
Pattern Details
- Type
- Dry Fly
- Seasons
- summer, fall
- Hook Sizes
- #6-12
- Hook Type
- 2XL dry fly hook
- Tying Difficulty
- Intermediate
- Imitates
- Stonefly adults, grasshoppers, cicadas, and other large terrestrial insects
Recipe & Materials
- Hook
- TMC 200R or equivalent, sizes 6-12Shop
- Thread
- 6/0 or 140 denier, color to match body
- Underbody
- Closed-cell foam, 2mm, color of choice
- Overbody
- Closed-cell foam, 2mm, tan or contrasting color
- Legs
- Medium round rubber legs, barred
- Wing
- Pearl Krystal Flash or EP Sparkle Brush
- Indicator Post
- Foam or yarn in high-visibility color
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Technique & Presentation
The Chubby Chernobyl is most effective as the top fly in a dry-dropper rig. Attach one or two nymphs off the bend of the hook using 4X-5X fluorocarbon tippet, spacing droppers 18-24 inches apart. The Chubby serves as both a strike indicator and an active fish-catching fly. Watch for the foam body to dip, hesitate, or move laterally, which indicates a take on the subsurface flies.
When fishing the Chubby as a standalone dry fly, present it with a dead drift along foam lines, current seams, and undercut banks. Trout often take foam patterns with savage strikes, so keep a firm grip on your rod. In slower water, the rubber legs provide subtle movement that entices fish even on a drag-free drift. A gentle twitch can sometimes trigger strikes from hesitant fish.
Color selection matters less than size and presentation, but local preferences exist. Tan and peacock are safe choices on most rivers. Purple and pink can be surprisingly effective. In general, start with a size #8 and adjust up or down based on water conditions and fish response.
History & Origin
The Chubby Chernobyl is a relatively modern pattern that evolved from the Chernobyl Ant, itself a foam-bodied attractor pattern developed in the 1990s. The 'Chubby' variant emerged in the early 2000s from the creative fly tying community in the Rocky Mountain West, though no single tier claims definitive credit for the design.
The pattern gained massive popularity in the 2010s as Montana guides discovered its unmatched performance as a dry-dropper indicator fly. Its name references the Chernobyl Ant's mutant-insect aesthetic, with the 'Chubby' moniker reflecting its stout, blocky profile. Today, the Chubby Chernobyl is arguably the most commonly used dry fly on Montana rivers during the summer months, with fly shops selling thousands each season.
Where to Fish This Fly
Madison River
Southwest Montana
Great dry-dropper indicator
Yellowstone River
South Central Montana
Float fishing staple
Gallatin River
Southwest Montana
Top pocket water fly
Arkansas River
Upper Arkansas Valley / Central Mountains
#1 pattern on the Arkansas; hopper-dropper anchor July through September
Colorado River
Grand County / Northern Mountains
Primary dry fly for float trips; hopper-stimulator hybrid July through September
Gunnison River
Western Slope / Black Canyon Country
Versatile attractor and hopper imitation, primary float trip dry
North Platte River
Central Wyoming
Hopper-dropper on the upper freestone near Saratoga
Snake River
Northwest Wyoming / Jackson Hole
The #1 Snake River pattern; hopper-dropper anchor from late July on
Green River
Southwest Wyoming
Cicada and hopper imitation; the summer money fly
Bighorn River (Wyoming)
North Central Wyoming
Hopper-dropper along grassy banks from July through September
New Fork River
Western Wyoming / Wind River Range
Hopper-dropper anchor through the meadow sections from late July
South Fork Snake River
Eastern Idaho
The #1 South Fork pattern: hopper/stonefly anchor for surface rigs
Salmon River
Central Idaho
The #1 Salmon River technique: hopper-dropper through the canyon
South Fork Boise River
Southwestern Idaho
Hopper-dropper along the timbered canyon banks
Metolius River
Central Oregon (Cascades)
Foam hopper pattern. Fish tight to banks in July-September.
McKenzie River
Willamette Valley / Cascades
Hopper-dropper rig along banks July-September
John Day River
Eastern Oregon (High Desert / Blue Mountains)
Foam bug / topwater for aggressive bass. Pop-pause-pop retrieve.
Owyhee River
Southeastern Oregon
Hopper pattern, the Owyhee's 'cheat code' July-September. Size 8-10.
Yakima River
Central Washington
Hopper-dropper anchor from late July through September
Methow River
North Central Washington, Okanogan County
Hopper-dropper anchor for mid-to-late summer
Truckee River
Western Nevada / Washoe County
Hopper-dropper anchor July through September along grassy banks
East Fork Carson River
Western Nevada / Douglas County
Hopper-dropper in meadow sections July-September
Ruby Mountains / Lamoille Creek
Northern Nevada / Elko County / Ruby Mountains
Chubby Chernobyl for aggressive brookies
Great Basin NP Streams
Eastern Nevada / White Pine County / Great Basin National Park
Chubby Chernobyl for aggressive brook trout
Rio Grande
Northern New Mexico / Taos County
Terrestrial attractor late summer along canyon banks
Pecos River
North-Central New Mexico / San Miguel & Santa Fe Counties
Terrestrial attractor August-September
Oak Creek
Central Arizona / Oak Creek Canyon
Small Chubby Chernobyl or beetle for summer terrestrials
East Fork Black River
Eastern Arizona / White Mountains
Chubby Chernobyl for summer terrestrials and attractor
Chevelon Creek
Central Arizona / Mogollon Rim
Chubby Chernobyl, primary dry fly for summer fishing
Davidson River
Western North Carolina / Pisgah National Forest
Terrestrial attractor, effective along grassy and rhododendron banks
Tuckasegee River
Western North Carolina / Jackson County
Terrestrial pattern for summer fishing along banks
Watauga River
Northwestern North Carolina / Watauga County
Terrestrial attractor along meadow banks
Wilson Creek
Western North Carolina / Caldwell County
Small terrestrial patterns
Deep Creek
Western North Carolina / Great Smoky Mountains National Park
Terrestrials from rhododendron canopy
South Toe River
Western North Carolina / Yancey County
Terrestrial patterns along banks
French Broad River
Western North Carolina / Asheville Area
Poppers and divers for topwater smallmouth action
Mitchell River
Northwestern North Carolina / Surry County
Terrestrials and poppers for trout and smallmouth
Kennebago River
Western Maine / Franklin County
Chubby Chernobyl in sizes 10-12 as a terrestrial/attractor pattern on summer afternoons.
Moose River (Jackman)
Northwestern Maine / Somerset County
Chubby Chernobyl in sizes 10-12 as a terrestrial/attractor pattern along forested banks.
Upper Connecticut River
Connecticut Lakes Region / Pittsburg
Terrestrial patterns in summer. Size 14-18.
Saco River
Mount Washington Valley / Carroll County
Terrestrials (hoppers, beetles) along grassy banks. Size 12-18.
Pemigewasset River
White Mountains / Grafton County
Terrestrial patterns along forested and grassy banks. Size 12-18.
Swift River
White Mountains / Kancamagus Highway
Terrestrials (ants, beetles) from overhanging trees. Size 14-18.
Ellis River
Mount Washington Valley / Carroll County
Terrestrials along forested banks. Size 14-18.
Ammonoosuc River
White Mountains / Grafton County
Terrestrials along farmland banks. Size 12-18.
Baker River
White Mountains / Grafton County
Terrestrials along farm banks. Size 14-18.
Mascoma River
Upper Valley / Grafton County
Terrestrials along rail-trail banks. Size 14-18.
Souhegan River
Southern New Hampshire / Hillsborough County
Terrestrial patterns mid-summer. Size 12-18.
Battenkill River
Southern Vermont / Bennington County
Small terrestrial patterns (ants, beetles) work along grassy banks. Size 14-18.
White River
Central Vermont / White River Valley
Terrestrial patterns for mid-summer fishing. Size 14-18.
Winooski River
Northern Vermont / Chittenden County
Terrestrial patterns along grassy banks mid-summer.
Lamoille River
Northern Vermont / Lamoille County
Terrestrial patterns for mid-summer. Size 12-18.
Dog River
Central Vermont / Washington County
Small terrestrials along wooded banks. Size 14-18.
Walloomsac River
Southern Vermont / Bennington County
Terrestrial patterns mid-summer. Size 14-18.
Mettawee River
Western Vermont / Rutland County
Terrestrial patterns along grassy banks. Size 12-18.
Otter Creek
Western Vermont / Addison County
Terrestrials in upper sections. Size 12-18.
New Haven River
Central Vermont / Addison County
Small terrestrials along wooded banks. Size 14-18.
Penns Creek
Central Pennsylvania / Centre County
Terrestrial patterns for summer bank fishing
Little Juniata River
Central Pennsylvania / Blair County
Terrestrial patterns for summer
Big Fishing Creek
North Central Pennsylvania / Columbia County
Terrestrials for summer
Yellow Breeches Creek
South Central Pennsylvania / Cumberland County
Terrestrial patterns for summer
Kettle Creek
North Central Pennsylvania / Clinton County
Terrestrial patterns for summer
Slate Run
North Central Pennsylvania / Lycoming County
Terrestrial patterns (ants, beetles, inchworms)
Tulpehocken Creek
Southeastern Pennsylvania / Berks County
Terrestrial patterns for summer
Related Dry Fly Patterns
Parachute Adams
The most versatile dry fly ever created. The Parachute Adams imitates a wide range of mayflies and serves as an effective searching pattern when no specific hatch is occurring. The white parachute post makes it easy to track on the water. Originally tied with conventional upright wings, the parachute version wraps the hackle horizontally around the post, allowing the fly to land flush on the surface with a more realistic silhouette. This low-riding profile is why many experienced anglers prefer it over the standard Adams. The mixed brown and grizzly hackle suggests the mottled coloring of countless mayfly species, from tiny Baetis to larger Callibaetis. On Montana waters, the Parachute Adams is the quintessential searching pattern. When you arrive at the river and nothing is hatching, tie on a Parachute Adams in size #14 or #16 and start prospecting. During active hatches, sizing down to match the naturals makes this fly deadly. It works on every Montana river from the riffles of the Madison to the spring creek-like waters of the Missouri below Holter Dam.
Elk Hair Caddis
Al Troth's iconic caddis imitation is a must-have on every Montana river. The elk hair wing provides excellent flotation, and the pattern effectively matches adult caddisflies throughout the season. Dead-drift, skate, or twitch it; all methods produce fish. The Elk Hair Caddis is one of those rare patterns that works from the moment caddisflies start appearing in spring through the last hatches of fall. The tent-shaped elk hair wing perfectly mimics the profile of a resting adult caddis, while the palmered hackle gives the fly exceptional buoyancy and creates the impression of legs touching the surface. Its durability is legendary; a well-tied Elk Hair Caddis can take dozens of fish before needing replacement. In Montana, caddis hatches are prolific on every major river. Mother's Day caddis hatches on the Yellowstone in late April and May are among the most anticipated events of the season. The Elk Hair Caddis is equally effective on the rock gardens of the Gallatin, the braided channels of the upper Madison, and the tailwater sections of the Missouri. Vary the body color between tan, olive, and green to match local populations.
Stimulator
An outstanding attractor dry fly and stonefly imitation. The Stimulator excels as a top fly in a dry-dropper rig. Larger sizes (#6-8) match salmonflies and golden stones, while smaller sizes (#12-14) suggest various stoneflies and caddis. The Stimulator's genius lies in its buoyancy and suggestive profile. The combination of a heavily palmered hackle, elk hair wing, and robust body allows it to ride high on turbulent water where lesser flies would drown. The swept-back wing silhouette works as both a stonefly and large caddis imitation, making it effective even when no specific insect is hatching. Trout see the Stimulator and recognize it as a substantial, calorie-rich meal worth rising for. In Montana, the Stimulator truly shines during stonefly season on the Madison, Yellowstone, and Gallatin rivers. Tie on a size #6 orange Stimulator during the salmonfly hatch in late June and fish it tight to the banks. As summer progresses, switch to smaller sizes in yellow for golden stones. The Stimulator also serves as an excellent indicator fly for a heavy nymph dropper, especially when wading pocket water and riffles where it can be challenging to track a strike indicator.
Purple Haze
A Montana-born variation of the Parachute Adams with purple dubbing. Created in the Gallatin Valley, this pattern has become a regional favorite that outperforms the standard Adams on many days, particularly during BWO and PMD hatches. The Purple Haze takes the proven Parachute Adams template and adds a subtle twist: a body of purple dubbing that seems to trigger something in trout that the standard gray does not. While purists may argue the color is unnatural, the results speak for themselves. Montana anglers have reported for years that the Purple Haze consistently outfishes the standard Adams, particularly on rivers that receive heavy fishing pressure. Theories about why the purple works vary. Some believe that the color more accurately represents the UV spectrum reflected by natural mayflies. Others suggest that the slightly different hue simply stands out enough on pressured water to be noticed without being refused. Whatever the reason, the Purple Haze has earned its place in the top tier of Montana dry flies. It is especially effective on the Gallatin, Madison, and Yellowstone rivers from late spring through early fall.
X-Caddis
Craig Mathews' brilliant caddis emerger pattern sits in the surface film, imitating a caddis struggling to break through the meniscus. Deadly during caddis hatches when fish refuse higher-riding patterns. The trailing shuck is key to its effectiveness. The X-Caddis fills a critical gap in the caddis life cycle that most fly boxes lack. While traditional dry flies like the Elk Hair Caddis ride high on the surface, the X-Caddis sits flush in the film with its body partially submerged and a trailing Z-lon shuck extending behind. This precisely imitates the moment when a caddis pupa breaks through the surface and begins to shed its pupal shuck, the most vulnerable stage for the insect and the moment when trout feed with the least caution. On Montana's caddis-rich rivers, the X-Caddis can make the difference between a frustrating day of refusals and a banner day of steady action. When you see trout rising during a caddis hatch but refusing your Elk Hair Caddis, the X-Caddis is the answer. It is particularly effective on the Yellowstone during the Mother's Day caddis hatch, on the Madison during summer evening hatches, and anywhere trout have become educated to conventional caddis patterns.
PMD Comparadun
A flush-floating mayfly imitation that excels during Pale Morning Dun hatches. The deer hair wing creates a realistic silhouette, and the pattern sits low in the film like a natural dun. Essential during PMD hatches on the Missouri and Madison. The Comparadun design is one of the most elegant solutions in dry fly fishing. By using a fan-shaped deer hair wing instead of traditional hackle, the fly sits directly on the water surface with its body in the film. This creates a silhouette that is nearly indistinguishable from a natural mayfly dun when viewed from below, exactly the perspective that matters to a feeding trout. The PMD version, tied in pale yellow and olive, is one of the most important patterns for Montana's prolific Pale Morning Dun hatches. PMD hatches on Montana's premier rivers are events that every serious fly angler should experience. On the Missouri River below Holter Dam, PMD hatches from late June through August produce some of the best dry fly fishing in North America. The Madison River's upper sections also host excellent PMD activity. During these hatches, trout can become excruciatingly selective, and the low-riding Comparadun is often the pattern that cracks the code when parachute and traditional dun patterns fail.