The San Juan Worm is one of the most basic flies in existence. Yet it is also one of the most effective. While some people refer to the San Juan Worm as a junk fly or even refuse to use it all together, the reality is that this simply fly consistently catches fish all over the world. The San Juan is easy to tie and easy to fish. If you’re interested in catching fish you should seriously consider carrying the San Juan Worm. There are many in my fly box.
The San Juan Worm originated on the San Juan River in the Southwestern United States sometime around 1970. You could probably figure that out from just looking at the name. It doesn’t take a genius to figure out what the San Juan Worm is supposed to be either. It is obviously meant to be a worm and it does look a lot like one. Blood worms are common in the San Juan River and fish like to eat them. That’s why this fly was originally created. There are some versions in colors like purple that might not look exactly like anything a fish would encounter in the wild. Those versions catch fish too.
The original San Juan Worm was red like a blood worm. The red San Juan Worm is still one of the most popular varieties. The pink San Juan Worm is probably just as popular these days. For whatever reason it is also the most effective of the colors in a general sense. I’ve caught a variety of species on pink San Juan Worms in locations as varied as Carolina lakes to glacial rivers on the Canadian border.
How to fish the San Juan Worm
Before I tell you about fishing with this fly, I want to let you know that I may earn commission when you make purchases through links on this page. This commission helps support my website, but it does not influence what I write. I only recommend products that I have found to be effective.
A San Juan Worm is constructed of a single piece of chenille affixed to a hook with thread. That’s it. There are variations that even simpler than that. An easy worm is made by simply tying a piece of chenille directly to the hook with an overhand not. More complicated versions involved things like sparkle and yarn. San Juan Worms can also be tied with a bead either at the head or somewhere along the hook shank. They work well when you want to get your fly deep.
This cutthroat took a San Juan Worm
Everyone knows that fish like worms. This is basic stuff. That’s why the San Juan Worm works so well in so many different situations. It’s also why some who view fly fishing as a higher pursuit than bait fishing or “worm dunking” look down on the lowly San Juan Worm. The fish themselves have no such standards. So the San Juan Worm is a good choice when you’re fishing for anything from trout to bass. It’s a great searching pattern that is especially useful for trout when there are no visible hatches.
The San Juan Worm is obviously a fly but you can fish it with spinning gear or a tenkara rod too. If you’re using a tenkara rod just tie it right to the end of your tippet and drift it through all the likely fish holding spots you can get to. If you’re spin fishing just attach a few split shot or a small float on the line to give you the weight to cast.
The EZ Float is a good choice for fishing a San Juan Worm on a spinning rod. It also helps indicate when a fish takes the fly. When it comes to fly gear you can match a San Juan Worm with pretty much any gear from a tiny 1 weight rod up to a big 8 weight for steelhead. Just match the fly size to your target, all the while remembering that big fish do eat small flies.
San Juan Worm tactics and applications
When fishing moving waters you fish a San Juan Worm like any other nymph. Basically you want to drift it along naturally with the speed of the current. You can fish it straight from the end of your line or fix it below a small float. Then you cast it out ahead of likely spots and allow it to “dead drift” with the current. The goal is to let the worm move at the same speed as the current. If it drags slower than the current or rockets down through a run you are very unlikely to catch a fish. If you get the worm to drift perfectly you are very likely to catch fish.
The San Juan Worm is especially effective in spring when rains and high flows wash worms into the water. But it works at other times too. I’ve caught enough trout out of extremely cold streams to know that. Fish seem to hit the fly almost by reflex. The fly works very well when drifted close to the bottom. When the water is very cold I drift it right against the bottom and in the slower flows and pockets. The bead head version comes in handy in that situation. Smaller San Juan Worms can also be fished as a dropped fly under either a floating dry fly or another sinking nymph.
This wild rainbow hit a San Juan Worm
If you’re fishing still water you basically have two choices. The first is to just cast the worm out and let it sink naturally. Then look for a bite as it falls. Once it is on the bottom the San Juan Worm is unlikely to catch fish with the possible exception of cruising carp or suckers that pass over the fly. Another method to fish the San Juan Worm in still water is to cast it out then work the fly to give it action. You can jig the fly by lifting and dropping the rod tip. You can crawl it along the bottom with a slow retrieve. Or you can twitch it slightly with your rod. All of these approaches can bring in fish.
I have used the San Juan Worm all over and it nearly always works. I’ve caught everything from arctic grayling in Colorado’s Joe Wright Reservoir to brown trout in Tennessee’s Little River and steelhead in Pennsylvania’s Elk Creek. I’ve also caught more panfish on the thing than I can count. I’ve caught cutthroats, rainbows, brook trout and even rock bass on this fly. I always make sure to have the San Juan Worm with me. Especially in pink and red.
Where to buy San Juan Worms
Like the green weenie, the San Juan Worm is often derided as a junk fly. Perhaps that is because it is so easy to tie, lacking the delicate wings seen on some dry fly patterns. I use this fly all the time. I am glad that the San Juan Worm is easy to tie because I go through a lot of them. Since they are so easy to tie, you might wonder why someone would purchase San Juan Worms at all. The truth is not everyone wants to tie flies. Some people prefer to use their free time fishing. There are also times where you find yourself near the water and in need of some flies. Whatever the case, it is now quite easy to find San Juan Worms all over the United States.
I would expect to see at least some variety of the San Juan Worm in nearly every fly shop in the country. Places like Little River Outfitters in Tennessee and Angler’s Emporium in Pennsylvania always carry the fly in a variety of sizes and colors. The same can be said of a lot of fly shops. Even the big chain stores will usually have at least one type of San Juan Worm in stock if they carry flies at all.
Of course flies can sell out of any given location so it can pay to be prepared. These days you can order San Juan Worms from a wide variety of online retailers. They even sell San Juan Worms at Amazon. So you can find any size or color you want and have it delivered right up to your door in no time.
So you can tie your San Juan Worms, pick them up in a store, or order them online. In any case you will be glad that you did. Carrying a variety of sizes and colors can help you fish a lot of different situations. Or you can narrow down your choices if you’re only fishing a particular water. Pink and purple San Juan Worms in sizes as large as 6 or even 4 can be very effective for steelhead. On the other, you can catch them on size 16 flies too. Just make sure the hooks are strong and your drag is set correctly. I typically carry San Juan Worms in red and pink in sizes ranging from 12 down to 16. I normally have some with bead heads and some without. This covers almost every situation I run into.