by Steve Sywensky
Flyfisher's Paradise Online

One of the toughest questions we answer every year concerns the precise time when anglers can encounter specific hatches. Since Central PA is blessed with abundant streams with prolific hatches, the question is an understandable one, but nonetheless it is difficult to ascertain exact emergence dates for aquatic insects, especially far in advance.

A query from a gentleman in Virginia we got back in February prompted this article. Our customer had fished Penn's Creek several times, but he had not met and fished (to borrow Charles Meck's terminology) the Green Drakes, the most prestigious of the many hatches on this big limestoner. He wanted to know, over three months in advance, when to be in Centre County to encounter E. guttalata.

Short of consulting a crystal ball while waving a dead rabbit over one's head and chanting an entomological mantra in Latin, it is extremely tough to place exact dates on insect activity. First, let's take a look at the Green Drake as a case study to illustrate why its hard to come up with the right answer. In addition, we'll examine a few other factors which impact even the time of day when hatches occur.

The Green Drake
Its easy to understand why flyfishers get excited about the Green Drakes. The fly is light colored and huge and therefore easy to see. Visions of big flies conjure up images of outsized trout that surface feed at no time other than the E. guttulata hatch. Like any other bit of flyfishing folklore, there is just enough truth to this assertion to perpetuate it. While I no longer chase the Drakes with the enthusiasm of youth, I've caught enough good fish on "Shadflies" (Centre County for Green Drake) to remember them fondly. Large fish hooked but not landed and perhaps bigger trout heard rising after dusk but not hooked are part of my memories, too, and its easy to catch "Green Drake fever." Even on those evenings when the trout seem to ignore the Drakes and feed on smaller fare, the spectacle of the Shadflies themselves, emerging by the thousands, is awe-inspiring.

Conventional local wisdom suggests Memorial Day as the start of the Shadfly, but, since that day itself is variable, it has little predictive value. Because the start of the Green Drake hatch is such a vital part of our yearly routine at the store, I've kept a list of both the earliest and latest dates for the initial day of emergence over the last thirty years. The two early dates are 22 May and 25 May. The two latest dates are 9 June and 11 June. Even if we arbitrarily toss out the earliest of the two dates and the latest of that pair, we still are left with a span of 15 days. This exercise should graphically illustrate why it is so difficult to provide an accurate assessment of the starting times of hatches.

All is not doom and gloom in the business of trying to meet and fish the Green Drake hatch, however. The two early emergence dates were probably caused by abnormally warm, dry springs. The two late hatch starts were undoubtedly occasioned by high water and very cool weather. Most Drake starting dates cluster solidly around 1 June. An angler planning to spend a week on Penn's Creek from say 28 May through 5 June would stand a significant chance of encountering guttulata activity.

On an annual basis the impact of the weather on emergence dates can at least be speculated upon. Warm, dry springs (and it appears that we are headed in that direction in Y2K) tend to push up the hatch calendar. In such years the combination of much sunlight and clear water seems to accelerate the maturation of aquatic insects underwater. Conversely, during wet, cool springs, in which sunlight is less intense and water temperatures rise more slowly, hatches occur later in the year.

Other Hatches, Other Times
The Green Drake hatch is but one of the emergences that the weather can affect. My favorite hatch, or maybe more accurately spinner fall, is the Trico. I savor both the dependability of these little bugs and the prospect of taking large fish on tiny dries. Although the Tricos are far from a secret, many anglers despair of fishing tiny imitations, and the streams are less crowded. Then, too, the Tricos occur at a time of year when business pressures wane somewhat, and I can be on the water more.

I was a Trico nut at least several years before being in the flyfishing business came to dictate my flyfishing schedule. Therefore, my records on the Tricos are more extensive than my Green Drake notes. Long experience on this hatch indicates that I should be on Spring Creek searching for Trico pioneers about 10 July. Good spinner falls are likely to occur around 15 July and in a cool, wet year, near 20 July.

As most of you undoubtedly realize, 1999 was one of the driest years on record in the Northeast. Stream levels that were down in 1998 became lower last year. Bob Duffus, longtime friend and customer from State College, reported the first Trico spinners a day before Independence Day. Scott McKee and I spent most of the following week happily fishing the first Trico spinner falls of the season--almost ten days before my records indicated they should occur. So much for the hatch charts!

Time of Day
Just like the weather can impact the starting time of hatches on an annual basis, the weather over the course of the day can affect the time of day emergences take place. Every angler of more than a little experience has witnessed hatches that occurred at the "wrong" time of day, and my records indicate not only good fishing at improper times, but also days when the fishing was slow because hatches did not emerge as anticipated. Two particular days with unexpected bonuses of insect activity jump out at me as I ruminate.

Although it seems an age ago when we had a cool, wet spring, 1996 was such a year. Stream levels were uniformly high, and water temperatures were colder than normal. On 28 May I had still not caught a fish on a dry fly. I fished a stretch of water on upper Bald Eagle Creek near Unionville, and, even that late in the year, I dug into my vest for my raincoat to use as an emergency windbreaker. It was flat out cold, even near noon, and the first three trout I caught inhaled a Royal Coachman Marabou, one of my favorite stockie flies.

As I walked upstream to the next set of runs and pocket water to fish the streamer, I stopped to study a long, flat pool. A few Orange Sulphurs struggled to escape the surface of the cold, high water. One was not fortunate and disappeared in a splashy rise. Soon, Sulphurs, Cahills, Gray Foxes, and Tan Caddis, all normal dusk emergers on this stream, blanketed the pool, and trout rose eagerly. This unanticipated afternoon bonanza broke my dry fly drought, and, by the time I had had enough at 3:00, the emergence was over. Those flyfishers arriving in the evening were probably very disappointed.

A similar situation prevailed on Spring Creek many years ago. Late May is a time of extended hours at the tying vise to fill the holes in our fly display, but I had planned to take the evening off to meet and fish Spring Creek's prolific Sulphurs. Because the day was quite cool, I left home early and was fishing nymphs by 5 PM. A half hour later Sulphurs began to hatch, and there were no other anglers in sight. Seventeen trout, with half over 12," were brought to hand on dry flies before the emergence was over. By 7:15 things were done for the evening, and I warned a good friend on my way back to the car not to expect much.

Water Temperature
There is a relationship not only between water temperatures and emergence times, but also between the rate of change in water temperatures and hatch times. The technical aspects of these factors are best left to aquatic entomologists like Greg Hoover, but the practical, fishing side of the impact of water temperature is something I've seen first hand.

After the conclusion of the major mayfly hatches, there are still ephemopteran emergences that can be relied on to furnish good fishing. The June-July emergences of large (#14-16) Blue-winged Olives (Drunella sp.) are just one of the summer hatches that can produce excellent rises.

On upper Bald Eagle Creek, a marginal freestoner subject to great fluctuations in water level and temperature, the large Olives are an early morning hatch. From 7-9 AM in early-mid-June, I've had good fishing with a #16 BWO Comparadun. Rarely do I see a rise or fly after 9:30 AM, since the water temperature often rises beyond the comfort levels of the naturals and the trout.

Although I have not fished this hatch on Penn's Creek, my informants indicate that 9-11 AM is the usual time to see Drunella emerge there. On Fishing Creek, a much colder stream, I've most commonly seen the large Olives at midday, when the water warms enough to encourage the nymphs to become active.

Such information is won only through hours on the water, but, if you are aware of water temperatures and their rate of change on the waters you fish, you can be more accurate in predicting the time of day when emergences will take place. The data become especially important after May, when water temperature fluctuations become more pronounced.

The "Upstream Migration" of Hatches
Flyfishers are fond of saying hatches "move upstream." What they really mean is that emergences typically begin earlier downstream and start progressively later upstream. This behavior is not unexpected, since downstream areas warm more quickly than upstream areas which are nearer springs and cold water tributaries.

The impact this has for encountering hatches is easy to understand. The Green Drake on Penn's Creek, for example, begins near Gleniron, and it may be as long as 5-7 days before it appears at its uppermost extent near the town of Coburn. Anglers literally follow the hatch upstream to be at the leading edge of the dum emergence, where the flies will be the heaviest and the trout the most receptive.

On longer-lived hatches, like the Sulphurs, Tricos, and Olives, for example, good hatches will be seen on downstream waters as much as two weeks before they occur on upper waters. On Spring Creek, for instance, the Milesburg area saw good Baetis hatches ten days earlier than heavy emergences were noted in the Bellefonte-Paradise section this season. To encounter early hatches of a given fly, therefore, go to the stream's lower reaches. To see hatches after they have concluded on the downstream waters, visit the stream's uppermost areas.

Summary
A variety of causal factors--weather, water temperature, changes in water temperature and the admitted interrelationships between these factors as well as the location of the stretch of stream fished -- all have a significant impact on your ability to encounter fishable hatches. If your fishing lives or dies by hitting hatches, you will surely be disappointed often. That's why most consistently successful flyfishers have learned to fish nymphs.

One other factor needs to thrown into the hatch hopper. Even on our relatively unspoiled Central PA waters where hatches are still heavy, not every stretch of water will see equally good emergences on a given day, even on widespread hatches like the Sulphurs. If you want to see good hatches with rising fish, start walking!

About The Author
Steve Sywensky is the managing partner of Flyfisher's Paradise, a position he has filled since l976. In addition to his other duties, he has tied some 300,000 flies for FFP and is a fly tying materials specialist who does most of the dyeing for the store. He has flyfished for more than forty years. You can email Steve at : Steves@flyfishersparadise.com

We thank Steve Sywensky (Steves@flyfishersparadise.com) for permission to reproduce this article on TotalFlyFishing.com. This article cannot be reproduced anywhere else without his consent.

More Articles from the Author
You can read more of his highly informative articles at Flyfisher's Paradise.

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