Intro Guide to Fly Fishing in the Spring

Intro Guide to Fly Fishing in the Spring

Spring is one of the best times of the year to fly fish. In an effort to prepare you for the upcoming season, we’ve compiled some of the most important things to know from what flies to use and the key hatches to target.

Table of Contents

Other Helpful Links

What is hatching in the spring season?

Many of the biggest insect hatches occur in the spring season from early March to June. Please note that hatches will vary based on altitude, water temperatures, and water levels. Excluding craneflies, here are the major species of insects that hatch in the spring that fly anglers should focus on.


There are many species of mayflies that are active during the spring. To name a few, there are Blue-Winged Olives, Sulphurs, March Browns, and Hendricksons.

Most mayflies hatch later in the afternoon and into the evening. Freshly hatched mayflies, aka “duns”, commonly hatch earlier in the afternoon before the “spinner fall.” Duns look like little sailboats drifting across the surface allowing their wings to dry before taking flight. The more humid and wet the weather conditions are, the longer duns drift on the surface.

The mayfly “spinner fall” is when egg-laying females return to the water to deposit their eggs by dipping the egg sack on the underside of their tail into the water. Male and female mayflies gather in large swarms above the water flying back and forth in a figure-eight. Eventually, they tire and descend onto the water as what we call, “spinners.”

Read more about spinners and duns here.


black caddis fly, adult caddis fly, caddis on leaf, black spring caddis, fly fishing caddis flies

A moth-like insect with tent-shaped wings that comes in a variety of colors and sizes. It is very common to see speckled brown, light tan, and black caddis streamside. In its early life stages, it is called a caddis pupa, which almost resembles an inchworm.

Caddis flies hatch most densely in the late afternoon and evening. In this “caddis fly hatch”, the egg-laying females return to the water to deposit their eggs. In addition, younger caddis flies are swimming up to the surface to emerge. Thankfully, caddis flies do emerge sporadically throughout the day, which allows for some dry fly action.

Here is how to catch trout on caddis flies.


stonefly insect on arm fly fishing

Stoneflies are insects with long flat wings and large segmented bodies. They can come in a bright yellow color or a darker grey color.

Yellow Sallies are a smaller species of stoneflies that are a yellowish tint, typically, ranging in hook size from a size #12 to #16. Golden Stoneflies are much larger in size ranging from a size #6 to #12 hook size.

There are darker grey species of small stoneflies that hatch in the winter and early spring called Little Black Stoneflies. On the other hand, there are large species of grey-colored stoneflies referred to as the Salmonfly ranging from a size #6 to #10 hook size.

Here’s how to catch trout with stoneflies.


Midges are small flying insects that are non-mosquito. They are a primary food source for trout year-round and hatch abundantly in all bodies of water across the United States. Midge larva and adults commonly range from a size #12 to #24 hook size depending on your local conditions. Personally, we like to fish a #16 to #20 hook size.

Here are some tips for fly fishing midges.


hopper dropper rig, how to fish a grasshopper fly, grasshopper fly, the fly crate, nymphing with an indicator

Terrestrials are insects and prey that do not originate from the water such as ants, beetles, inchworms, bees, crickets, and grasshoppers. Terrestrials will consistently produce fish for those wanting to cast dry flies, especially on small streams and rivers with grassy meadows on the banks. Trout will feed on terrestrials opportunistically as it is entirely dependent on insects falling into the water from above, which happens sporadically without warning. They are also the perfect flies for using dry-dropper setups and really working a large area of water quickly. 

Here are some tips for using terrestrial flies to catch large trout.

What time of day do flies hatch?

Most insects hatch in the morning and from the afternoon into the evening. During the spring and summer, hatches tend to slow down at around noon, and then intensify in the late afternoon into the late evening.

During this time it’s a good opportunity to grab a snack or do some nymphing. Splitting the river into a grid system and prospecting the open water with dry-dropper rigs is a great way to find trout still feeding in the lull.

Looking for more information on hatches for the spring? Click here to read more about the top early spring hatches.

What flies should I use in March?

In March, temperatures are still climbing from the winter lows. Few hatches occur this early in Spring unless water temperatures increase dramatically to bring caddis and mayfly hatches early. You’re best chance to catch fish will come from nymphing and retrieving streamers. With that being said, you may run in to situations that warrant casting a dry fly so carry some basic dry fly patterns. Overall, here are the 6 different trout flies that we pack in our boxes for the month of March.

  1. Adams Parachute: Size #12 – #16
  2. Dirty Hipster: Size #14 – #18
  3. Beaded Scud: Size #14 – #16
  4. Bead Head Woolly Bugger: Size #8 – #12
  5. Rainbow Warrior Midge: Size #18 – #20
  6. Tag Jig: Size #14 – #18

What flies should I use in April?

In April mayflies, caddis, stoneflies, and midge activity picks up significantly. Dry fly action is much more likely as large mayfly species like the March Brown and smaller species like the Blue Winged Olives are prevalent. Towards the end of the month you will begin to see a heavy caddis hatch. In select streams, large stoneflies will provide sporadic dry fly action. You may even have the occasional winged ant hatch that may draw some attention. Flows can be quite high with rain and snowmelt, so using eggs and worms can be a great way to take advantage of these high-protein food sources being washes up from the bottom.

While you can fish with dry flies, nymphing will be the most productive means to catch trout. Overall, here are the 12 different trout flies that we pack in our boxes for the month of April.

  1. Adams Parachute: Size #12 – #16
  2. BWO Parachute: Size #18 – #20
  3. Bead Head Woolly Bugger: Size #8 – #12
  4. Rainbow Warrior Midge: Size #18 – #20
  5. Tag Jig: Size #14 – #18
  6. Neversink Caddis: Size #14 – #16
  7. Royal Wulff: Size #12 – #14
  8. Micro Chubby Chernobyl: Size #12 – #14
  9. Frenchie Jig Nymph: Size #14 – #16
  10. Tungsten Worm: Size #12
  11. Dirty Hipster: Size #14 – #18
  12. Beaded Egg: Size #10 – #12

What flies should I use in May?

May brings higher water temperatures and consistent hatches during the day; caddis, mayflies, midges, beetles, and ants are on the menu! Afternoons and evenings will be the best time of day to catch trout on dry flies while early in the day will offer great nymphing potential as insect larva and pupa are increasing more active. Most species of mayflies and caddis flies lay their eggs and emerge most densely in the late afternoon.

To mention a few, here are some of the biggest hatches to look out for:

  • Blue Winged Olives (BWOs – mayfly)
  • Grannom Caddis Fly
  • Sulphur (eastern mayfly)
  • Midge
  • Little Black Caddis
  • March Brown (mayfly)

Much hasn’t changed with our list. Overall, here are the 12 different trout flies that we pack in our boxes for the month of May.

  1. Eastern Sulphur Parachute: Size #14 – #16
  2. Soft Hackle Hare’s Ear: Size #14 – #16
  3. Adams Parachute: Size #12 – #16
  4. BWO Parachute: Size #18 – #20
  5. Bead Head Woolly Bugger: Size #8 – #12
  6. Rainbow Warrior Midge: Size #18 – #20
  7. Tag Jig: Size #14 – #18
  8. Neversink Caddis: Size #14 – #16
  9. Royal Wulff: Size #12 – #14
  10. Micro Chubby Chernobyl: Size #12 – #14
  11. Frenchie Jig Nymph: Size #14 – #16
  12. Tungsten Worm: Size #12
  13. Dirty Hipster: Size #14 – #18
  14. Bead Head Hare’s Ear: Size #14 – #16

Buy 40 of our favorite Trout Flies for the Spring!

Click the button below to shop 40 flies. We hand-selected our best performers from this article and assembled them into one assortment.

How do you fish in spring runoff?

Fish dislike high muddy water just as much as us. They, typically, stay close to the edges and down close to the bottom to avoid the powerful currents. Due to the friction of the water meeting the banks of the stream, water along the edges can be drastically slower than the rapid center. The combination of slower moving water along the bank and the bottom of the stream makes it safer for fish to swim. So, seams, eddies, and slow water along the banks are the ideal location for fish seeking refuge from the storm to rest.

Fish the Edges

The life of a trout is all about consuming vs. conserving calories.  High water also means swift currents and fighting against that torrent takes a lot of energy for a fish.  When the streams swell, trout will push to the edges of that current, sometimes right off the banks, to escape the rushing water.  It’s not terribly uncommon to not even have to wade during these high water events because the fish will be holding between the bank and the middle current in the softer areas that offer some sort of respite. 

Get Upstream of Tributaries 

Figuring out high water becomes a game in understanding entire watersheds.  A burst of rain upstream of one significant tributary can blow out the entire main stem downstream of the confluence.  A good rule-of-thumb is to keep working higher upstream into a drainage to get above as many tributaries as you can.  With each tributary avoided, that’s that much less water entering the stream you want to fish, and that can help lessen the blow after a snow melt or heavy rain. 

Find the Pools

Much like fishing the edges, finding a deep pool can really help anglers catch fish during high water.  Riffles and runs that fish well at normal flows will all of a sudden be raging rapids, but deeper pools can hold some semblance of normalcy in response to the increase in water flow.  Areas that might have once had little current will now have some, but it’s still a better bet than trying to navigate the heavy moving water that’s not only difficult on the trout, but potentially treacherous to wade in.  Fish will flock to these slow water refuges and it’s possible to have a banner day just by locating one of these places that will hold fish during high water. 

Find the Soft Water

The biggest key for fishing streams and rivers in runoff is finding the soft water.  Riffles and runs that are usually spots for trout can now be raging torrents that aren’t even wadable, much less fishable.

Finding the soft spots, usually near the banks, is the way to go during this time.  In trying to escape the heavy current in the middle of the river, trout will push to the edges trying to find the reprieve, and as such, fish can be absolutely stacked in those slower-moving areas.  In some ways, runoff can be easier to fish because it narrows down where the fish can be.  Eliminate the heaviest of current, then look for the soft water that also holds some depth and odds are pretty darn good there’s some trout present.

Head for the Lakes

Runoff can quickly make a favorite stream or river a messy or dangerous option to fish. 

Swift water is not to be trifled with, and a few people each year perish in the gushing currents.  High mountain lakes can offer a perfect respite for those looking to get an adventure and great fishing! 

While they are impacted by runoff in their own way (namely swift inlet/outlet streams and colder water temps), from ice-off until early fall the alpine lakes of the Rockies are terrific options.  They can hold a variety of fish, and it’s a stark contrast to the streams and rivers at lower elevations.  Targeting cruising cutthroats with dry flies while standing beneath towering snowy peaks is certainly a fine way to keep your mind off of the heavy runoff down below!

  • Long stretches of water followed by a deep pool
  • Deep water
  • Eddies behind obstructions like fallen trees, boulders, etc.

This is exactly where you want to place your flies.

What’s the difference between a dun and a spinner?

A dun and a spinner are mayflies but in two different stages of their adult lifecycle. Duns are mayflies that have just emerged, or molted, from their nymphal stage. These are the mayflies you commonly find drifting on the surface like little sailboats. An easy indicator are their cloudy and off-color wings. Trout will typically display faster more splashy takes to eat mayfly duns before their take flight. Dun mayflies wait until their wings are dry enough to fly away, which is why mayfly hatches can last longer on overcast and rainy days. 

Spinner flies are adult mayflies in the final stage of their life cycle. In the spinner stage, mayflies have just completed mating in a massive crisscrossing swarm above the water. The females usually develop a noticeable ball of eggs on the underside of their tails. Male and female wings transition from a cloudy, grey color to completely transparent during the final molt.

Now, this swarm of spinners will gradually descend closer and closer to the water in what is called a “spinner fall.” The females will dip their tails into the water to release the ball of eggs until they eventually tire and die, while the males will fly until they are spent. Thousands of mayflies will coat the surface within just a few minutes. Depending on the density of the hatch, spinner falls may only last a few minutes while others can last up to an hour or two. When you look closely at the behavior of trout rising to eat these dead mayfly spinners, you’ll notice that they lightly sip the spinners versus aggressive, splashy takes.

How do you fish a spinner fly?

Spinners are the dying or dead mayflies that drift flat on the surface. It’s important that when you fish spinner flies that your fly remains still on the surface in what’s called a dead-drift. Any movement might distinguish yours apart from the naturals. Using lighter tippet (5X, 6X, or 7X) and a nice long leader will allow you to make the delicate, gentle casts spinner flies require.

When you cast spinner flies you’ll want to aim 3-feet above the surface and let your line lower to the water. This will make a soft presentation without spooking any rising trout.

What does a rusty spinner imitate?

Rusty spinners simply describe the brown, rusty dubbing color fly tiers use to make certain spinner flies. These specific flies imitate fully molted mayflies that turn various shades of brown such as some Baetis species.

Fly Fishing Made Easy 👍

Our Quarterly Fly Club ships 1,000’s of flies to anglers all across the United States. Receive curated fly assortments selected for the season with in-depth articles on how to fish them. Great for beginners to learn and for intermediates to discover new flies.

Share this post

Join Waitlist We will inform you when the product arrives in stock. Please leave your valid email address below.