Tricos Month to Month and Coast to Coast

What are the two most common hatches in the United States? One has got to be the Little Blue-Winged Olive Dun. You’ll find that hatch common in just about every state. For example, in the Southwest you can’t fish a river without seeing this important small mayfly. In Arizona and New Mexico the Little Blue-Winged Olive is the pattern of choice. Don’t go near the San Juan in New Mexico or Silver Creek in Arizona without plenty size 20 imitations, especially in the spring and fall. In Colorado’s North Fork of the Cache la Poudre outside of Fort Collins I fished for an entire afternoon when blue-wings appeared. And Oregon’s Metolius River holds a spectacular blue-winged hatch. The same goes for the Northeast. The heaviest hatch I ever encountered on Big Fishing Creek in Pennsylvania and on South Branch of the Raritan in the Ken Lockwood Gorge in New Jersey was the Little Blue-Winged Olive Dun.

What’s the second most common hatch in the United States? It has got to be the Trico. (To look at pictures of both hatches click on “Mayfly Identification.” The Little Blue-Winged Olive is top row, middle; and the Trico is bottom row, left.) All of us who fish the hatches look forward to the small, but important Trico hatch and spinner fall. This ubiquitous hatch is also found appearing just about every month of the year. Yes, I said every month of the year. Next to the Little Blue-Winged Olive the Trico is found on almost as many streams and on some it appears almost the entire year. You don’t believe me? Look at some of the rivers and the time of the year that I’ve met this hatch in the past two decades.

June through October
Late summer is when the Trico is at its peak. Up and down the East Coast at that time you’ll find plenty of Trico hatches to match. The limestone waters of Pennsylvania and Virginia especially boast good populations of this genus. Fish Virginia’s Mossy or Beaver Creeks in early morning and your in for a matching-the-hatch treat with the Trico spinner fall. Pennsylvania limestone waters like Monacacy, Little Lehigh and the Yellow Breeches Creeks host hatches every morning from June through October. Farther northern Pennsylvania limestone streams like Spring, Spruce and Bald Eagle Creeks, start their hatches in mid to late July.

But, the Trico also appears on many of our prominent eastern freestone streams. The Delaware River, the Beaverkill, and even the lower Lehigh River host the Trico for much of the late summer and fall. Even small freestone streams like Bowman Creek in northeast Pennsylvania holds some Tricos. As a side note: This is the first freestone stream on which Vince Marinaro fished a Trico spinner fall. Read more about this incident in Fishing Limestone Streams. (Order by clicking on “Books”)

But, Midwestern and Western waters also boast great summer Trico hatches. and spinner falls. The hatch on Montana’s Big Horn River often doesn’t first appear until August but it can be impressive. Most of the large rivers of the West have Trico hatches. The Missouri River in Montana has one of the heaviest hatches. If you fish Midwestern waters like the Au Sable in August or September you’ll see these spinners in the air mating.

September to November
And Trico spinner falls can be impressive and important in the fall. I was alone on the McKenzie River just outside of Eugene, Oregon more than 10 years ago one late October morning. I noticed a few rainbows rising and peered across the river to look for insects emerging or falling. Just before the McKenzie entered the Willamette River I saw thousands of these tiny Trico mayflies just 10 to 15 feet above the surface. It was a bonus hatch with thousands of Tricos appearing and trout rising on that late October morning.

November through January
Until a decade ago I had fished Trico spinner falls in more than 20 states and from June through October. That was before I began fishing some of the streams and rivers of the Southwest. Never in a million years did I expect to see or fish this summer hatch in the middle of the winter. But, I did. And, until a few years ago only a handful of fly fishers knew of the winter Trico hatches. I fished the Salt River just outside Phoenix, Arizona around midmorning in November. As I approached the river I saw thousands of tiny spinners mating in the air. But, I fished the Salt River again on New Year’s morning just a half mile above Granite Reef and I again found Trico spinner’s falling onto the surface. This wasn’t a very heavy spinner fall, but one nonetheless. So, November through January--and all year long--you can encounter Trico hatches on the Salt River.

February through May
What about February, March and April? Do Tricos appear anywhere in the United States that time of the year? One of the most spectacular and rewarding Trico falls as far as the number of trout caught occurred on the upper Verde River in Cottonwood, Arizona on February 15. That morning Craig Josephson and I caught more than 40 trout on a size 24 Trico Spinner imitation. Can you imagine doing that well in the middle of the winter, catching that many trout and on a size 24 spinner—and a Trico Spinner to boot? And I came back to the upper Verde that year in March, April and early May and I again hit hatches of this small but important mayfly.

Most areas of the United States hold two generations of Tricos each year. And each generation lasts about 48 days. So after the first generation of spinners lays their eggs it will be approximately 48 days until those eggs have hatched, the nymph has emerged as a dun, the spinners have laid their eggs and the life cycle is completed. In most areas the eggs from the second generation go into hibernation until the following May. Some very cold areas of Canada hold only one generation and areas of the Southwest have many generations. In the Phoenix area there are seven generations each year.

Have you ever seen a male Trico dun? If you have you probably haven’t seen many. Why? A few decades ago Robert Hall conducted a study of the Trico for his doctoral requirements. In that study he found that male duns often emerge from 10 P.M. until 2 A.M. So, don’t worry about matching the male dun. The olive-bodied female dun emerges from 5 A.M. to 11 A.M. depending on the weather conditions and the time of year. From October to April the female emerges late in the morning. During the summer female duns emerge just at dawn. Spinner falls begin as early as 7 A.M. in the heat of the summer. In November, December and January I’ve witnessed spinner falls as late as 2 P.M. Female spinners fall first then a few males.

Pattern construction is tremendously important. Make certain you carry some floating and weighted spinner patterns. If you fish a sinking spinner add a couple wraps of .005 lead to the body before you tie it. For both the wet and the floating female spinner patterns tie a dun tail; the back third of the body, pale cream; the front two thirds of the body, dark brown; and white for the wings, tied spent. For a sinking pattern I use opossum or angora fur for the body and Krystal Flash for the wings. For the floating version I use poly for the body and wings. Tie a body of very dark brown for the male spinner.

What type of river or stream do you like to fish? Do you like to wade, use a float tube, or a McKenzie-type boat? Where do you find the heaviest Trico hatches? Where are some really small mountain streams that hold the Trico spinner fall? Here are a few of the answers:

Heaviest Hatch: Missouri River, Craig, Montana

Midwinter Hatches: Salt River, Mesa, Arizona

Late Winter and Early Spring Hatches: Upper Verde River, Cottonwood, Arizona

Small Mountain Freestone Stream Hatches: Elk Creek and Hoagland Branch, upper Lycoming County, Pennsylvania

Big River Hatches (float trips): Delaware River, New York; Missouri River, Montana

Far Eastern Hatches: Delaware River, New York; Housatonic River, Connecticut.

Far Western Hatches: Willamette and McKenzie Rivers, Eugene, Oregon

Where and when will you fish the ever-present Trico spinner fall? Will you fish it when it normally appears in July, August and September? Or will you travel to the far West or Southwest and see this diminutive, but often-productive spinner in the fall or winter? Tricos— month-to-month and coast-to-coast—the choice is up to you.

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