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San Juan Worm Fly – One Of The Best Flies

The San Juan Worm is one of the best flies of all time. It works on just about any trout stream in the world. San Juan Worms are available in many colors, and they are one of the easiest flies to tie. It is one of the most famous flies, and for good reason.

Why do San Juan Worms work so well? What makes this fly one of the top producers of fish?

This article will cover the reasons we fish San Juan Worms, and why you should think about adding some to your fly box. There are times of the year when the fish are really keyed in on worms. It is good to have a nice assortment of San Juan Worms to be prepared for these situations.

Aquatic Worms Are Abundant In Rivers

All trout rivers have lots of aquatic worms. These worms vary in color and size, but they are a huge part of a trouts diet. They pack a lot of calories, and they’re an easy meal.

During rain storms and spring runoff, earth worms will make their way into the river as well. These worms are often larger than aquatic worms, and trout will eat them as well.

The San Juan Worm was developed on the San Juan River in New Mexico. Fly anglers quickly found out that a worm fly could easily fool trout. All they needed was some chenille on a hook, and they had one of the best flies ever. Although many flies are complicated with lots of materials, the San Juan Worm is just a single piece of chenille on a hook.

Word quickly spread and the San Juan Worm is now available everywhere. Original colors were red and brown, but anglers have started fishing many different San Juan Worm colors. Pink, wine, purple, etc – all of these colors work.

As fly anglers, we are always thinking about bug hatches and how to match them. However, often times a simple fly will get the job done. This is why the San Juan Worm has gotten so popular over the years.

The San Juan Worm assortment below is a great way to get multiple colors of worms in one package. I highly recommend it for beginners who are trying to fill up their fly boxes.

San Juan Worms Are Easy To Tie

I would argue that the San Juan Worm is the easiest fly to learn to tie. Beginners can learn how to tie them in a couple minutes. It is often the first fly that is taught in fly tying classes.

This also means that it is easy to produce lots of these flies at the vise. You can whip out a dozen of them pretty quickly, and it will save you some cash as opposed to buying them. I like to tie a bunch at the beginning of the season, which will last me throughout the warmer months. Filling up a worm box is easy, even for beginner tyers.

The short video below by InTheRiffle demonstrates how simple it is to tie a San Juan Worm.

This also makes the San Juan Worm a great guide fly. Fly fishing guides can fill their boxes with these for their upcoming guide trips. When their client loses one, it isn’t a big deal since they’re so easy to tie.

Countless Variations Of The San Juan Worm

As mentioned before, there are so many colors you can try with this fly. You can leave them unweighted, or you can add a tungsten bead to get them down.

You can even use two different colors of chenille – which will make a two tone worm. There really are endless variations of the San Juan Worm. You can play around with it and see what colors and combos work best. I find that on certain rivers, a particular worm does really well. Here in Colorado, brown is my favorite color and it produces lots of trout. Up in Wyoming, purple does really well and is preferred by many Wyoming anglers.

Squirmy worms have also become very popular. These are just San Juan Worms that are tied with a rubber material instead of chenille. They have a lot more movement in the water, which looks more realistic to the trout. Squirmy worms just flat out catch fish. They have quickly gained popularity, and many fly anglers now prefer them over a regular San Juan Worm.

I really like the jigged versions of squirmy worms. They sink fast with a tungsten bead and they snag the bottom less often. The pink jigged squirmy worms below have quickly become one of my go-to patterns. They work especially well in dirty water, but even picky tailwater trout will eat them. It is simply a fly that is hard for a trout to resist.


Although fly fishers like to make things complicated and fish technical flies, sometimes you just fish what works. The fact is, trout streams are loaded with worms and trout eat them on a daily basis. Having some San Juan Worms in your fly box is never a bad idea.

They work especially well when you show up to a new river and you’re not sure what to use. They make a great “searching” fly when you’re not sure what is hatching or what the trout are eating. Being such a universal fly, it is great for anglers traveling around to different rivers.

They make a great attractor fly and I will often use them as the first fly in my nymph rig. San Juan Worms really get trouts attention, and they will often move several feet just to eat the fly.

Whether you end up buying them or tying them, make sure to have some San Juan Worms for your upcoming fly fishing trips. They are often the hot fly that is the ticket to catching lots of trout. Your buddies may bum some off of you when they see how well they work.