I honestly can't remember the last time I headed to a big freestone river without a handful of the pat's rubber leg fly tucked away in my box. It's one of those patterns that doesn't look like much when it's sitting in a fly bin—certainly not as flashy as some of the modern perdigons or those intricate realistic nymphs—but once it hits the water, everything changes. It's essentially the blue-collar worker of the fly fishing world. It isn't pretty, it isn't fancy, but it gets the job done when other flies are just taking up space.
If you've spent any time around fly shops, you might have heard people call it a "Girdle Bug." That's because the Pat's is basically a modernized, souped-up version of that classic pattern. It's designed to imitate a stonefly nymph, which is a staple food source for trout in almost any river with a decent current and some rocks. The thing about stoneflies is that they're big, they're meaty, and they take a couple of years to mature, meaning they're available to fish year-round. That makes the Pat's a high-confidence fly regardless of the season.
What Makes This Fly So Effective?
The real magic of the pat's rubber leg fly lies in its movement. Those wiggly rubber legs are the star of the show. In a fast-moving current, they vibrate, kick, and twitch in a way that just screams "life" to a hungry trout. Even when the fly is dead-drifting, the slight turbulence in the water keeps those legs moving. Most nymphs are static, relying on their silhouette to fool a fish, but the Pat's adds that extra layer of sensory input.
Another reason it works so well is its profile. Stoneflies are chunky. When a trout sees a big Pat's tumbling along the bottom, it sees a high-calorie meal that's worth the effort of moving out of its holding lie. It's like offering a steak to someone who's been snacking on saltines all day. In off-color water or during the high flows of spring runoff, that large profile and the vibration from the legs make it much easier for fish to track down.
Tying the Pat's Rubber Leg Fly
One of the best things about this fly is how easy it is to tie. If you're just getting into fly tying, this is a great pattern to start with because it's almost impossible to mess up. You don't need expensive jungle cock feathers or perfectly tapered CDC.
All you really need is some variegated chenille (often called "coffee" or "turd" colored), some rubber legs (Spanflex is a popular choice because it's durable), and a whole lot of lead wire. You want this fly to be heavy. Stoneflies live on the bottom, under rocks, and in the "boundary layer" of the river where the water moves a bit slower. To get the fly down to where the fish are, you need weight.
I usually wrap a thick layer of lead or lead-free wire around the hook shank before I even think about the chenille. Then, it's just a matter of tying in the legs—usually two at the back, two in the middle, and two at the front—and wrapping the chenille forward. It's a five-minute fly, which is great because you're going to lose a few. Since you're fishing them deep and near the rocks, snags are just part of the game.
Choosing the Right Colors
While you can get creative, most anglers stick to a few tried-and-true colors for the pat's rubber leg fly.
- Black and Tan: This is the classic "coffee" look. It's a killer imitation for a Golden Stonefly or a larger Skwala.
- Solid Black: Great for those big Salmonfly nymphs. If you're fishing a river where Salmonflies are a big deal, you need these in sizes 4 through 8.
- Olive: Works wonders in rivers with a lot of vegetation or where the stoneflies have a greener tint.
- Brown/Orange: A sleeper choice for late summer and fall.
The beauty is that you don't have to be exact. The fly is more of a "general impression" of a bug rather than a scientific replica. As long as the size is roughly right and it's bouncing along the bottom, the fish usually don't mind if the shade of brown is a little off.
How to Fish It Effectively
Most people fish the pat's rubber leg fly as part of a nymph rig. It's a fantastic "lead fly." Because it's heavy and bulky, it acts as an anchor for your entire rig, helping smaller, unweighted nymphs get down into the strike zone quickly.
I'll often run a Pat's as my top fly and then tie a smaller dropper—like a Pheasant Tail or a Zebra Midge—about 18 inches below it. It's a classic "steak and eggs" combo. The big fly grabs their attention, and the small fly offers a delicate snack. You'd be surprised, though, how often the trout skip the appetizer and go straight for the big Pat's.
Another fun way to fish it is on a "hopper-dropper" rig in the summer. If you use a big enough foam grasshopper on top, you can hang a Pat's underneath it. This is lethal near undercut banks. Just be careful with your casting; a heavy rubber-legged fly can create a bit of a "bola" effect if your loop gets too tight, leading to some impressive tangles.
When to Reach for the Pat's
Is there ever a bad time to fish a pat's rubber leg fly? Honestly, not really. But there are definitely times when it shines. High water is the obvious one. When the river is "big" and pushed up into the willows, the fish move toward the edges to find relief from the current. A big, heavy nymph dropped right into those soft pockets along the bank is a recipe for success.
It's also my go-to when nothing else is happening. If there isn't a visible hatch and the usual suspects aren't producing, I'll put on a Pat's and just cover water. It's a "searching" pattern. It triggers an aggressive response. Sometimes a trout isn't even hungry, but seeing those legs twitching past its face is enough to make it strike out of sheer instinct.
A Note on Tackle
Because this fly is heavy and usually fished in fast water, don't be afraid to beef up your tippet. I rarely fish a pat's rubber leg fly on anything lighter than 4X. If I'm in a river known for big fish or very rocky terrain, I'll jump straight to 3X or even 2X. The fly has enough mass that the fish aren't going to be "leader shy" about the thickness of the line. Plus, you want that extra strength when you inevitably have to pull the fly off a submerged log or a stubborn rock.
A 5-weight or 6-weight rod is usually the best tool for the job. Casting a weighted Pat's on a 3-weight is a good way to give yourself a headache (literally, if the fly hits you in the back of the head). You need a rod with a bit of backbone to turnover that weight and to handle the fish that are brave enough to eat such a substantial meal.
Final Thoughts on the Pat's
At the end of the day, fly fishing is often about confidence. If you believe a fly is going to catch fish, you'll fish it better. You'll be more focused on your drift, you'll react faster to the indicator, and you'll stay on the water longer. The pat's rubber leg fly is one of those patterns that earned its spot in my box by proving itself over and over again on different rivers across the country.
It's not a "match the hatch" fly in the traditional sense, and it's certainly not going to win any beauty contests. But if you want a fly that sinks fast, moves naturally, and looks like a protein-packed meal to a big trout, you can't do much better than this. Next time you're at the vise or at the shop, make sure you grab a few. Your fly box—and the fish—will thank you for it. Just be prepared to lose a few to the river gods, because if you aren't bouncing them off the bottom, you aren't fishing them right.