Category: FLY FISHING

By Son Tao

It’s Hopper Season—the time of year when grasshoppers, crickets, katydids, and beetles seem to be everywhere, especially near the water’s edge. If you’re a fly angler, you know this is prime time. Terrestrials start showing up in trout diets, and the explosive surface takes are unforgettable. But have you ever noticed some insects seem to jump or fall into the water for no obvious reason?

Turns out, not all of them are careless. Some are being controlled.

Meet Spinochordodes tellinii, a parasitic hairworm that turns ordinary grasshoppers into unwitting swimmers. Its goal? To manipulate its host’s brain and send it straight into the drink.

The Underwater Beginning

The life cycle of this hairworm begins in water, where its microscopic larvae float, waiting to be consumed by an unsuspecting terrestrial insect. This can happen when a grasshopper drinks contaminated water or eats another small organism that’s carrying the parasite.

Inside the insect, the hairworm grows silently and stealthily. Coiled tightly within the host’s body cavity, it can stretch to several times the host’s length, yet remain unnoticed. To the fly fisher’s eye, that hopper on the bank still looks like a juicy, twitchy meal.

When the Water Beckons

But at some point, the worm matures, and its mission changes. It can’t reproduce inside the host. It needs water.

That’s when it starts to manipulate its host’s behavior. Using chemical signals, the hairworm interferes with the insect’s central nervous system, altering its natural aversion to water. What was once a cautious grasshopper now starts wandering toward streams and ponds. Eventually, it jumps in—or falls in—almost like it was drawn by some unseen force.

As anglers, we see this behavior on the water and chalk it up to clumsiness or wind. But some of those land-based insects are the victims of parasitic mind control.

The Worm Emerges

Once the host hits the water, the hairworm makes its dramatic exit. Long, thread-like, and often startling to witness, it wriggles out of the insect’s body, killing it in the process. Free at last, it swims off to find a mate and continue the cycle.

Insect down. Parasite succeeds. Trout feast.

Why This Matters to Fly Fishing

For the fly fisher, understanding these natural rhythms and hidden ecological dramas can provide a serious edge. During late summer and early fall, terrestrials are an important part of a trout’s diet. Knowing that some of these bugs enter the water not by accident but by design helps explain the heightened feeding behavior seen on rivers and creeks during hopper season.

This also highlights why hopper patterns that land with a splash or flutter erratically can be so effective—they mimic not just the appearance of a land bug, but the unnatural, confused behavior of an insect under parasitic influence.

So the next time you’re tying on a foam hopper or watching trout rise to a beetle pattern, remember: some of those insects weren’t blown in. They were pushed by something inside.

How to Fish the Hopper Bite: Matching the Mind-Controlled Meal

Fly fishing during hopper season is all about imitating chaos. These insects don’t land softly and drift peacefully like mayflies. They’re twitchy, panicked, and often erratic—especially when they’re under the influence of something like Spinochordodes tellinii.

1. Choose the Right Fly

• Foam Hoppers: Patterns like the Chubby Chernobyl, Amy’s Ant, and Dave’s Hopper, create disturbance, and resemble a bug that’s out of place in the water.
• Leggy Bugs: Flies with rubber legs and gangly profiles like Whitlock’s Bright Spot Beetle imitate the flailing limbs of a struggling terrestrial.
• Beetles and Crickets: Don’t overlook patterns like the Monster Beetle, Hegan’s Ant, Dave Whitlock’s Bright Spot Cricket patterns—especially around shaded banks.

2. Consider Fishing a Dropper

Hairworms aren’t just fantasy—they exist. Trout sometimes key in on worms after seeing them emerge from a dying insect. You can simulate this by tying a red or pink San Juan Worm or Squirmy Wormy as a dropper beneath your hopper. It’s not always “pure dry fly,” but it’s deadly effective.

3. Presentation Tips

• Plop It Loud: These insects don’t land like ballerinas. Let your fly hit the water with a little drama—it signals a vulnerable meal.
• Twitch It: Every few seconds, give the fly a slight twitch. Mimic an insect in distress or trying to self-rescue.
• Target Edges and Undercuts: Terrestrials usually fall in from bankside vegetation, so focus casts near grassy edges, overhanging limbs, and riffle-to-pool transitions.
• Midday Magic: Unlike traditional hatches, hopper fishing is best from late morning through the heat of the afternoon when insects are active and wind may knock them down.

Choosing the Right Rod for Hopper Season

Casting large, wind-resistant hopper patterns—or hopper-dropper rigs—requires more than just finesse. You need a rod that can turn over bulky flies, punch through wind, and still deliver with precision near tight banks. This is where the 6 weight is king.

Here are a few top-tier choices that excel during terrestrial season:

Orvis Helios 6wt
A powerhouse with laser accuracy. The Helios 3D is ideal for punching foam hoppers into headwinds and laying them down gently. Its backbone handles hopper-dropper rigs with ease, and the tip action still protects tippet.

Scott Centric 6wt
Fast, responsive, and extremely intuitive. The Centric gives you power when you need it but has a buttery flex that keeps casts smooth and roll casts easy. A perfect balance for hoppers in driftless creeks or big Western rivers.

Winston Pure 2 6wt
For anglers who prefer finesse and dry-fly feel, the Pure delivers a soft touch. Ideal for those fishing single hoppers in calmer conditions. The slower action allows for delicate presentations in tight quarters.

Scott Session 6wt
Session rods are high-performance hand-crafted fly rods that blend some of Scott’s most acclaimed design approaches with their latest materials and technologies. This combination creates rods that bring together high line speed, exceptional loop control and accuracy with a light and lively feel in the hand.

Don’t Forget the Floatants

For effective dry fly fishing, quality floatants like High N Dry, Loon, and Frog’s Fanny Double Duty are top choices. These products help keep your flies riding high and dry on the water. High N Dry offers both gel and liquid floatants with great all-around performance. Loon has a range including Aquel (gel), Fly Dip, and Dust (Shake n Bake powder). Frog’s Fanny Double Duty combines a desiccant and floatant in one, perfect for reviving soaked flies, especially CDC patterns.

Nature’s Darker Currents

Spinochordodes tellinii is just one example of parasites that alter host behavior to complete its life cycle. Others include Toxoplasma gondii, which makes rodents unafraid of cats, and Ophiocordyceps fungi, which turn ants into zombie spore spreaders.

These interactions remind us how complex, interwoven, and sometimes unsettling the natural world can be. As anglers, we’re not just participating in a sport—we’re stepping into a web of ecological relationships older than we can imagine.

So enjoy Hopper Season. But know that beneath the splashy takes and twitchy strikes lies a story even more fascinating than the fish that eat the fly.

Fly fishing in the summer can be incredibly rewarding, but it also demands a strong sense of responsibility—especially when targeting trout. Warmer temperatures, lower water levels, and increased angling pressure can stress trout populations. Understanding trout behavior in the heat, practicing ethical fishing, and following conservation-minded techniques are key for sustainable fishing. This guide outlines the essentials of summer fly fishing and offers practical steps for ethical and enjoyable outings.

Understanding Trout Behavior in Summer

Trout thrive in cold water. As temperatures exceed 65–68°F (18–20°C), trout experience increasing stress. Above 68°F (20°C), fishing can become harmful or fatal due to low oxygen levels and buildup of lactic acid during a prolonged fight. Even if they swim away quickly, it does not necessarily mean they will survive. During summer, trout seek out:

• Cooler, oxygen-rich waters
• Deep pools and shaded areas
• Spring-fed creeks and tailwaters

Feeding patterns also shift. Early mornings and late evenings are prime feeding times, especially during peak insect activity from mayflies, caddisflies, and terrestrials like ants and grasshoppers.

Plan your trips to coincide with cooler parts of the day:

• Best times: Early morning and late evening
• Avoid: Noon to 4 p.m., when water is warmest

Fish where it stays cool:

• High-elevation streams
• Spring-fed creeks
• Tailwaters below dams

• Summer Fly Fishing Tactics

  Trout are more cautious in clear, low summer water. Adapt your strategy:

  • Use longer leaders for natural fly presentation
  • Dry fly fishing is ideal with terrestrial insects
  • Stay stealthy: Move slowly, wear neutral colors, and keep a low profile

  Pack a variety of beetles, ants, and grasshopper patterns. Match your presentation to how these insects behave naturally.

  Catch and Release Ethics

  Practicing responsible catch and release is essential in summer:

  • Use heavier tippet to “rope them in” quickly: Reduces fight time and stress
  • Use barbless hooks to minimize injury and ease release
  • Wet your hands before touching fish
  • Limit air exposure to under 10 seconds
  • Use rubber or soft mesh nets like the Fishpond Nomads
  • Revive fish gently by holding them upright in the current

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  Monitor Water Temperature

  Carry a stream thermometer like the Fishpond Riverkeeper. Follow this simple guide:

  • Below 65°F (18°C): Safe to fish
  • 65–68°F (18–20°C): Fish cautiously and release carefully
  • Above 68°F (20°C): Avoid fishing

  Many ethical anglers stop fishing for trout entirely when temperatures hit 68°F.

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  Minimize Environmental Impact

  Ethical anglers go beyond the catch:

  • Avoid trampling vegetation to protect stream banks and habitats
  • Pack out all trash, including fishing line and tippet scraps
  • Lead by example: Promote responsible fishing among peers

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  Support Conservation

  Get involved with conservation efforts:

  • Join organizations like Trout Unlimited
  • Volunteer for river cleanups or habitat restoration
  • Participate in citizen science projects monitoring trout populations

  Advocate for water management policies that maintain healthy stream flows—especially in drought-prone regions.

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  Make Thoughtful Choices

  If trout waters are too warm, consider targeting warmwater species like bass or carp. These fish are more tolerant of higher temperatures and can offer an exciting challenge on a fly rod. Shifting focus helps protect stressed trout populations while still enjoying time on the water.

  Ethical fishing means knowing when to step back:

  • Avoid overfished streams, even if temperatures are safe
  • Explore less-pressured waters to give trout a break

  Consider avoiding certain techniques like nymph rigs or indicators if they increase fight time or risk deeper hooking. Always prioritize fish welfare.

  Teach the Next Generation

  Pass on good habits:

  • Teach kids and newcomers how to fish respectfully
  • Explain proper handling and temperature awareness
  • Encourage care for both the fish and the environment

  Instilling conservation values early helps ensure the sport’s future.

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  Conclusion: Responsible Summer Fly Fishing

  Summer fly fishing is more than catching fish—it’s about stewardship. With increased stress on trout, our role as anglers is to:

  • Fish during cooler times
  • Handle trout with care
  • Monitor water temps
  • Support habitat conservation

  Ethical fly fishing is a mindset of respect and sustainability. Each thoughtful decision—whether releasing a fish quickly or educating a fellow angler—contributes to healthier trout populations and a stronger angling community.

  In the end, ethical summer fishing benefits everyone—especially the trout.

  Photos and article by Son Tao. son@feather-craft.com