The San Juan worm (why is it so controversial?)

Rarely has a fly fishing pattern sparked so much controversy as the San Juan worm. This unassuming little fly has caused many debates among fly fishers. In this post we share everything you need to know about the San Juan worm.
San Juan Worm

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Rarely has a fly fishing pattern sparked so much controversy as the San Juan worm. This unassuming little fly has caused many debates among fly fishers as to whether fishing with this worm pattern is true fly fishing or not. Almost as many problems as the great catch and release debates!

Taking a step away from the debate, the basic fact is that this San Juan worm fly will catch you fish – lots of them! It’s also one of the first patterns that beginners learn to tie by themselves.

So we here at Fly Fisher Pro couldn’t resist including it in our new series of detailed fly guides and reviews of the best dry fly, streamer, and nymphs.

Let’s dig deeper and explore more about the San Juan Worm! Our report covers everything you need to know about this fly, including its origins, how to tie this pattern, plus tips on how and where you should fish this pattern.

San Juan Worm

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About the San Juan Worm

The San Juan Worm is a small pattern which imitates aquatic worms, also known as annelids. With its simple construction and convincing presentation, many anglers love to fish this pattern during heavy spring rains.

The worms are at their most active from March to May. After torrential rain or runoff, they rise through the mud and silt and are often swept off into the current, where the trout just love to snack on them.

Worms are easy prey for trout and a big burst of protein and energy, too. As the worms tend to become waterlogged and sluggish in the water, the trout can easily catch them.

Lots of fly anglers use the San Juan worm to lure out big old brook trout from their hiding spots along riverbanks. But where did this fly first come from, and why was it created?

San Juan Worm Fly

History of the San Juan Worm

As the name suggests, the worm was first developed by a fly angler fishing the San Juan River in New Mexico. Little red bloodworms are prolific in the San Juan River, and this fisherman wanted to come up with a fly to imitate them effectively. Thus, the San Juan pattern was born.

The San Juan River is a tailwater fishery, and the water levels fluctuate wildly because water from the river is used further downstream for irrigation.

The high water levels of this fast-flowing river cause the worms to emerge from the silty riverbed and muddy riverbanks, and high numbers end up in the water. This makes them one of the major sources of forage for trout and other fish, particularly during the spring. It was just a matter of time before someone came up with a worm pattern on this river!

There are rumors as to who this fly fisherman was, but no clear evidence pointing to one individual. However, since its creation in the late 1960s or early 1970s, this little worm has earned its place in fly boxes all over the country. While it was first developed for the San Juan River, it has seen success much further afield, too.

Where To Fish Your Worm Fly

From the great western rivers to smaller trout streams, this pattern works exceptionally well for catching trout and bass. It’s particularly suited to silty rivers, streams, and lakes, but it’s not just limited to these locations.

Aquatic worms are found in waters all over the world. If you haven’t tried fishing the worm in your local river, we recommend that you give it a go and see if you get any bites!

Having said that, it’s well-known that the San Juan fly fares especially well in murky, dirty water conditions. You’ll be surprised how well this attractor pattern does, even in coffee-colored waters.

If the conditions are right, with high water levels, this worm pattern won’t disappoint.

San Juan Worm Fly

San Juan Worm Review: Materials

This is a very simple fly, and you can tie it in many different ways. The basic components are found in most fly tying kits, and you can get creative with colors and materials too, if you like.

  • Hook: Whichever hook you prefer to use
  • Thread: Uni Thread works well in 6/0 or 8/0. The best colors to use are red, tan, pink, and purple, but you could also try orange, brown, or hot pink.
  • Body: Chenille in a matching or similar color to your thread. Common color choices include red, brown, purple, pink, yellow, and even fluorescent orange!

How To Tie the San Juan Worm

The San Juan is one of the most straightforward fly fishing patterns to get your head around. If you’re a fly tying newbie, this is a great fly to get you started. Once you’ve mastered this fly, you’ll be excited to move onto more advanced patterns.

All you need is some chenille in purple, red, or pink, plus some matching thread. It takes less than 10 minutes of your time, and you’ll have this pattern tied and ready to go. Check out our recommendations on the best fly tying kit options here to get started.

You’ll find loads of fly tying videos online. Here’s a helpful video tutorial that will walk you through the steps of fly tying the San Juan Worm. These tips should help you get stuck in!

How To Fish the San Juan Worm Fly

There are lots of different ways to fly fish with the San Juan pattern, so here are a few tips. One simple but effective technique is to set up your fly rod, and dead drift it like a trailing nymph along the bottom of the water column. For smaller worms, you can also fish it with a greased leader.

Some fly anglers choose to fish this fly under an indicator or add split shot to help it get to the right depth quickly. It’s critical to get the weight of your split shot right, especially when fly fishing in fast-flowing water, so that you can get your flies down to the right level. If you get your split shot set up correctly, you’ll be sure to see a lot of success!

This pattern is also ideal for fly fishing in low light conditions. Here, everything will rely on the presentation of your fly, so you should aim to make it look as realistic and active as possible.

You can get your fly to wiggle just like a worm by twitching your fly rod or doing quick, short strips. Either way works and will catch the attention of any fish lurking nearby!

You can also use this fly for tenkara fishing or Czech nymphing with a lot of success. The versatility of this fly makes it a great addition to every angler’s fly box and fishing gear.

The Wrap Up

The San Juan Worm is a unique and immensely effective little fly if used in the right conditions. We think that it deserves a spot among your flies, fly fishing supplies, and accessories. Don’t let the purists get to you. Hook this beauty on and get back to catching more fish!

If you’ve enjoyed this guide/review of the San Juan worm, don’t miss our other fishing gear and accessories review and guides! Why not share this review online or drop us a comment or email with your thoughts? We love to hear from you guys.

San Juan Worm Fishing Flies | 36 Flies | Tri-Color...
San Juan Worm Fishing Flies | 36 Flies | Tri-Color…
Chemically Sharpened Hooks; Great All Around Fly; Use by Itself or Dual Dropper

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