July Hatch Guide: Everything You Need to Know for Colorado’s Hatches in July
- brianchilbert
- 7 days ago
- 10 min read
July is one of the most exciting months of the year for Colorado fly fishing. Water levels are settling, trout are feeding aggressively, and nearly every major food source is available somewhere on the river. From technical morning trico spinner falls to violent caddis eats, big golden stoneflies, yellow sallies, PMDs, and wind-blown hoppers, July rewards anglers who understand what trout are seeing and when they are seeing it.
The best anglers in July do not simply tie on a favorite fly and hope for the best. They watch the water, look at the bugs, identify the stage of the insect trout are targeting, and adjust their approach throughout the day.
Here is everything you need to know about the most important Colorado hatches in July.
Midges: Still Important in July, Especially Early
Many anglers stop thinking about midges once summer arrives, but that is a mistake. Midges remain an important food source throughout July, especially during the early morning hours.
Midges are small, tube-like insects that range from size 18 to size 26, with size 20 through 22 being most common. Their bodies are generally black, olive, gray, or dark brown. Adult midges have narrow wings that lay straight back over their body when resting on the surface. They are often subtle and easy to overlook, but trout rarely overlook them.
Midge activity is usually strongest from first light through mid-morning. Before larger insects become active, trout may feed selectively on midge larvae, pupae, emergers, and adults. If you see small, steady rises with no obvious large insects on the water, midges are often the answer.
Best July Midge Flies
Day Saver Midge Cream, size 22
Day Saver Midge Black, size 22
RS2 Black, size 22
How to Fish Midges in July
Fish midge patterns under a small indicator or as the trailing fly beneath a larger attractor nymph. In slow pools, seams, and slicks, use light tippet and a delicate presentation. A size 22 midge can be difficult to see and fish, but it can be the difference between a slow morning and a great one.
CRO Guide Matt Fletcher Pro Tip: “When fish are sipping early and you cannot clearly identify what they are eating, do not be afraid to go small. A size 22 midge or RS2 behind a larger fly gives trout a familiar, easy meal without spooking them.”
Tricos: The July Morning Main Event
For many Colorado anglers, the trico hatch is the defining dry-fly event of July. Tricos dominate calm mornings and can create some of the most technical, rewarding fishing of the season.
Tricos are tiny mayflies with three tails. They typically range from size 20 through 26, with size 22 being the most common. Their appearance can vary slightly. Some are nearly all black with light gray wings that stand straight up like a sailboat. Others have a black thorax with a cream or light olive abdomen.
Tricos often begin appearing around 8:00 a.m. and can dominate the water until roughly 10:00 a.m., depending on weather, water temp, and river section. Adults gather in huge mating swarms over the river, often hovering above riffles and slick water. Trout may eat adults, but the best fishing often begins after mating, when the insects die and fall to the surface as spinners.
A trico spinner has wings spread flat to either side of its body. When trout are keyed in on spinners, they may feed with slow, deliberate sips in glassy water. These fish can be extremely selective.
Best July Trico Flies
Eric’s Trico Spinner, size 22–24
Angel Wing Trico, size 22–24
Juan’s 180 Trico, size 22–24
How To Fish The Trico Hatch
Trico fishing requires precision. Use long leaders, often 9 to 12 feet, and light tippet in 5X or 6X. The fly must drift naturally. Even slight drag can cause a selective trout to refuse.
Focus on foam lines, soft seams, tailouts, slicks, and slower edges where spent spinners collect. Watch individual fish and make intentional casts rather than repeatedly throwing at random rises. Position yourself downstream when possible, make a reach cast, and give the fly enough slack to drift naturally.
CRO Guide Brian Hilbert Pro Tip: “With tricos, the fly is only part of the equation. A perfect drag-free drift matters more than the exact pattern. If a trout refuses your fly, do not immediately change patterns. First, change your angle, lengthen your leader, lighten your tippet, and improve the drift.”
Yellow Sallies: A Small Stonefly With Big July Importance
Yellow sallies are one of the most overlooked but productive July hatches in Colorado. These small yellow stoneflies are generally active from approximately 10:00 a.m. through 3:00 p.m., though adults may remain present throughout the day.
Yellow sallies range from size 14 through 18. Adults are usually pale yellow with transparent brown or gray wings that lay straight back over the body. Unlike mayflies, yellow sallies do not emerge directly from the surface. They crawl from the water onto rocks, banks, bridge pilings, and shoreline vegetation before emerging into adults.
Once airborne, yellow sallies fly in a slow, hovering fashion that often resembles a tiny helicopter. Trout may feed on adults near banks, but the nymph stage is equally important. Their nymphs are active in faster water and are frequently dislodged into the drift.
Best July Yellow Sally Flies
Iron Sally, size 14–18
UV Sally, size 14–18
Galloup’s Butch Sally, size 14–18
How to Fish Yellow Sallies
Fish yellow sally nymphs through faster riffles, pocket water, current seams, and shallow runs. A light nymph rig with enough weight to reach the lower water column can be extremely effective. As adults become active, fish a yellow sally dry tight to the bank, alongside structure, and in softer water near riffles.
CRO Guide Matt Weldon Pro Tip: “Yellow sallies are often strongest in fast water. Do not overlook the skinny, choppy runs that anglers walk past. Fish a size 14 or 16 yellow sally nymph through those pockets, and be ready—trout often eat it hard.”
Caddis: The Most Consistent July Hatch
Caddis are one of the most important insects in Colorado during July. They can be present all day, but early morning and evening are often the best times to find concentrated adult activity.
Adult caddis look like small moths. They flutter, bounce, skate, and occasionally dive across the surface. Adults generally range from size 14 through 20, with size 16 being most common. Their colors include tan, black, olive, and brown.
Caddis larvae resemble miniature caterpillars or worms. They may be olive, cream, tan, or rusty brown. Many live in protective cases, while others are free-living. Caddis pupae are especially important because they ascend quickly through the water column before emerging. Their movement can trigger aggressive trout feeding, and many pupae show fluorescent green or light olive coloration in the abdomen.
Matching the stage of the caddis life cycle that trout are targeting is critical. Trout may be feeding on larvae near the bottom in the morning, pupae rising through the water column during emergence, or adults fluttering across the surface in the evening.
Best July Caddis Flies
Hilbert’s Sexi Caddis Pupa, size 14–16
Juan’s Kryptonite Caddis, size 16–18
X-Caddis, size 14–18
How to Fish Caddis in July
When trout are feeding subsurface, fish larvae patterns near the bottom through riffles and runs. If you see flashes, swirls, or violent takes just below the surface, trout may be chasing ascending pupae. Swing a caddis pupa through the current, allow it to rise at the end of the drift, and hold on.
During evening adult activity, fish an X-Caddis or similar adult pattern dead-drifted through seams and foam lines. If trout are aggressively chasing adults, add occasional subtle twitches or skates to imitate a struggling insect.
CRO Guide Chase Kelly Pro Tip: “When caddis are active, pay close attention to where trout are eating. If you see aggressive boils, swirls, or flashes just beneath the surface, they are often chasing ascending pupae—not adults. Fish a caddis pupa on a short dropper or swing it through the end of a drift, then let it rise toward the surface before picking up to cast again. That lift is often when the eat happens.”
Pale Morning Duns (PMD’s): The Classic Midday Mayfly Hatch
Pale Morning Duns, commonly called PMDs, are one of July’s most dependable midday mayfly hatches. They typically become active between 1:00 p.m. and 3:00 p.m., though weather and river conditions can shift the timing.
PMDs are small yellow to amber-colored mayflies that range from size 16 through 20. Earlier in the season, larger size 16 PMDs are common. As July progresses, many rivers see smaller size 18 and 20 insects.
Trout may key on PMDs in four distinct stages of the life cycle:
Nymph:
The immature insect lives below the surface, often near the river bottom. PMD nymphs are active before emergence and are an important subsurface food source.
Emerger:
The insect rises from the bottom toward the surface and begins transitioning into an adult. This is often the most vulnerable stage, and trout frequently target emergers just below the surface film.
Adult:
The dun has emerged and sits on the surface with upright wings. Trout may eat adults drifting naturally through feeding lanes.
Spinner:
After mating, the adult dies and falls to the surface with its wings flat. Spinner falls can create selective feeding in slick water, especially later in the afternoon or evening.
Best July PMD Flies
Day Saver May PMD, size 16–18
Sexi Top May PMD, size 18
Sparkle Dun PMD, size 18
Hi Viz PMD Spinner, size 18
How to Fish PMDs
Start with a PMD nymph or emerger when you see insects beginning to appear but few fish rising. As trout begin feeding on the surface, switch to a Sparkle Dun or Sexi Top May PMD. If fish are sipping spent adults in slower water, use a PMD spinner pattern.
CRO Guide Brian Hilbert Pro Tip: “When PMDs are hatching, watch how trout are feeding. A splashy rise may mean they are eating adults. A subtle nose or fin breaking the surface often means they are taking emergers just below the film. Match the feeding behavior before you change flies.”
Golden Stoneflies: Big Bugs, Big Meals
Golden stoneflies are one of the most exciting July food sources for Colorado trout. These large insects spend roughly three years as nymphs before crawling out of the water to emerge on rocks, bridge pilings, logs, and shoreline vegetation.
You may see golden stonefly shucks stuck to rocks or bridge supports throughout July. These empty shells are a clear sign that adults are present and trout are likely accustomed to seeing both nymphs and adults.
Golden stonefly nymphs range from size 14 through size 8, with size 10 being most common. Adults are typically size 8 through 10. Nymphs are large, dark, and heavily segmented with prominent legs. Adults are usually golden yellow to tan with darker markings and long wings folded flat over their bodies.
Best July Golden Stonefly Flies
Pat’s Rubber Legs, size 10
Twenty Incher, size 10
Royal Chubby, size 10
Hilbert’s “Sexi Golden Stone” is a very realistic and durable stonefly imitation. Check out our YouTube video to learn to tie it!
How to Fish Golden Stones
Fish Pat’s Rubber Legs or a Twenty Incher deep through fast runs, pocket water, and boulder gardens. Golden stonefly nymphs prefer heavily oxygenated water, but they are regularly knocked loose in heavy current. Trout know they are a substantial meal.
For dry-fly fishing, a Royal Chubby is an excellent imitation and a highly visible indicator fly. Fish it tight to banks, under overhanging vegetation, along boulder lines, and through broken water. Golden stonefly patterns also make excellent hopper-dropper flies.
Terrestrials: Hoppers and Ants Take Over on Windy Days
By July, terrestrial fishing becomes a major part of the Colorado fly fishing equation. Grasshoppers and flying ants are especially important on windy afternoons, when gusts blow insects from bankside grass, trees, and brush into the river.
Trout are opportunistic feeders. A hopper or ant falling into the water is a large, high-calorie meal that can bring fish out from under banks, logs, and deep structure. When nothing else seems to be working, a terrestrial pattern fished tight to the bank can often produce.
Grasshoppers come in a wide range of colors, with yellow and tan being most common in July. They range from size 14 through size 8, with size 10 and 12 being most common. Flying ants are generally cinnamon colored or black with dark translucent wings. They range from size 14 through size 22, with size 16 through 18 being most common.
Best July Terrestrial Flies
Yeti Hopper, size 10–12
Chubby Chernobyl, size 8–10
Ant Acid, size 16
How to Fish Terrestrials
Fish hoppers and ants tight to the bank, under willow cover, along grassy edges, and beside structure. Make accurate casts and allow the fly to land with a subtle plop. In windy conditions, a slightly more aggressive presentation can actually help imitate a natural insect being blown into the water.
A hopper-dropper rig is one of the most effective July setups in Colorado. Use a large Yeti Hopper or Chubby Chernobyl as your indicator fly, then trail a PMD nymph, caddis pupa, yellow sally nymph, or stonefly beneath it.
CRO Guide Tim McAdow Pro Tip: “On windy afternoons, fish the bank harder than you think you need to. Trout are waiting for hoppers to fall in. Make the first cast count, keep the fly close to cover, and do not pull it away too quickly.”
Take Your July Bug Game to the Next Level With CRO
July is full of opportunity, but it can also be overwhelming. A river may have midges in the morning, tricos by 8:00 a.m., yellow sallies and caddis by late morning, PMDs in the afternoon, and hoppers or ants blowing into the river by evening.
That is why booking a trip with Colorado River Outfitters is one of the best ways to improve your fishing. Our guides have the hatches dialed in, understand how trout respond to changing conditions, and know exactly where to fish each insect throughout the day. We are bug nerds, passionate anglers, and many of our guides tie their own flies to match the constantly changing conditions. We do not just tell you what fly to use, we explain why it works and how to fish it.
Whether you are looking for a guided wade trip on the Eagle River, a float trip in the Colorado River or Roaring Fork River, or a day of personalized instruction, CRO is ready to help you catch more fish and become a better angler.
Call or text Colorado River Outfitters at 970-236-1937 to book your July fly fishing trip.
Follow Colorado River Outfitters for daily fishing reports, hatch updates, fly tying videos, guide tips, and Colorado trout fishing content:
Thank you for reading our July Hatch Guide. Be sure to subscribe to the Colorado River Outfitters blog for the latest Colorado fishing reports, hatch updates, fly recommendations, and expert guide insight throughout the season.
Good luck out there!
-The CRO Team
Comments