SULPHURS!

(Ephemerella Dorothea, invaria)

  by Joseph Tutino "JOE.T."

Sulphurs (AKA pale evening Dunn, Little Maryatt) start appearing at the time of year when I first start to enjoy the full bloom of spring. I savor the longer days and at last, the first of the evening hatches!

Sulphurs are one of the most prolific hatches of the year as well as one of the most complex. The Dorotheas are usually much more important and prevalent to the fly fisherman than the Invaria species. Under normal conditions the Dorotheas start hatching up in the valley streams of PA about the first week of May (in NJ about the 3rd week) and they get going around the 4th week of May, in the Catskills. The Invaria species usually start appearing a week earlier than the Dorotheas. Emergence times can vary depending on water levels and temperatures. The hatches typically last about a month and in some cases, especially on rich tailwaters like the branches of the Delaware, it can last up to three months.  The following is a description of the species, it's forms, and how to fish imitations to catch trout.

First, let's talk about nymphs. Most ephemerella nymphs are very stocky with feeble legs and tails. The Invaria nymphs are 7 ½ to 9 ½ mm long (size 12/14 hook) with three tails and the body being yellowish brown in color with a dark "V" on the thorax. The Dorothea nymphs are 6 to 7 ½ mm long (size 16-20) with three tails and the body being yellowish brown to med olive brown in color with a light "V" on thorax. 

The Dorothea nymphs are found in various habitats but are primarily quiet water wellers whereas the Invaria species are found in faster water. Prior to their emergence, the nymphs become very active. Like most ephemerella nymphs they wiggle when swimming to the surface which usually triggers the fish into feeding.

A great technique to use at this point of the emergence is to put a little weight (about 8-10 inches) above the nymph and cast the fly directly across from you and mend the line once upstream, allowing the nymph to reach the bottom. Then let the fly start its swing below you. Once the swing is complete don't bring it in just yet, let it sit out there for a few moments than strip it at about 3 inches at a time with a pause in between and be sure to hold onto your rod!   Another great method is to cast the nymph pattern with weight 8-10 inches above the fly up and across stream and "high stick" the nymph along the bottom. As it starts to get below you, let it swing to the surface; as it swings wiggle the tip of your rod up and down to mimic the action of the natural.

When nymphing at this time of the emergence, I like to position myself right in the seam of slower and faster water at the lower end of the riffles where the riffs just start to flatten out while working my way slowly downstream from there. When the nymphs are escaping their shucks in or just under the film (surface tension) they drift for some time before they actually break through the surface; as a dun this is another trigger point for the trout. This is a time to be very observant of "bulging" under the surface and looking for backs and dorsal fins of trout breaking the surface. My favorite technique to use at this point of the emergence is to cast a floating nymph (sits in the film) down and across to the fish, just as one would with an emerger or an adult pattern. Now, try twitching the pattern ever so slightly as it drifts towards the fish. If this method fails to produce it may be that the Dorotheas are transforming into duns a few inches under the surface. In this instance, tie on a weighted soft hackle pattern about 8-12 inches behind a floating emerger pattern and use the same technique as with the floating nymph. When using any tandem setup I really like the flourocarbon tippet by Rio to connect the two flies.

With Subimago (adults), the Invaria species are 8-10 mm long (size 12/14) with olive yellow body color and light gray wings. The Dorothea species are 6-7 1/2 mm long (size16-20) with pale yellow body color and light gray to creamy wings. Invaria species usually hatch in faster water earlier in the day between 12:00-5.00p.m. especially with cloudy conditions. When there's a heat wave look for them to hatch in the later a.m. hours or in the evening. Optimum water temps for the Invaria to hatch is between 50-60 deg. The Dorothea earlier in the season start to emerge around 6.30 p.m. and as the season progresses and the weather really starts to warm up they hatch towards dusk and even after dark . Typically the optimum water temps for the Dorotheas to hatch are between 55-65 degrees. On cooler days especially cloudy the Dorotheas can start their emergence in the late afternoon. Telling the two apart is very easy just due to the size difference but be alert to both because they can hatch simultaneously and the trout can become very selective to one.

There are many factors that make Dorotheas a complex hatch including but not limited to the weather, water temps, duration of hatch on a particular river, and fish being ultra selective to different stages of emergence. Size, silhouette, and color of the natural are very important factors; especially when you have prolific hatches that last for long periods on a certain river. The trout see these bugs day in and day out and get real keyed on certain stages of the emergence. The most important thing is to be very observant of the types of rises being seen.

RISE FORMS:

The technique I always use for dry fly fishing especially for large wild selective trout on rich tailwaters or spring creeks is the down and across reach cast. The first thing you want the fish to see is your fly not your leader or line and get the best possible drag-free drift. For those of you that do cast across stream or up and across stream try the reach cast, or the down and across technique. You might find it works better for you in certain situations.

While casting to the sippers or faint rises during the Dorothea hatch I start with a cripple pattern or spent spinner pattern.  I also like to use a comparadun or parachute pattern with a cripple or spinner pattern tandem tied 12-18 inches behind the lead fly. Keep in mind that the tandem setup doesn't always work as well with lower water or with "mini-currents" (it's hard enough to get a drag free drift with one fly, let alone two.) At that point I work each pattern alone until success.

If I'm casting to the splashy rise, I go right to the comparadun. If that's not working for me I go with a down winged emerger pattern. The body sits right in the film with the wings on the surface. The key with this pattern is the silhouette as it gives the appearance of a nymph with a shuck just coming off and the wings down before they go upright. This is a very vulnerable stage for the insect! When fish are rising everywhere and the water is covered with duns and I still see backs and fins breaking the surface, I go right to a CDC emerger tied on a scud hook with a weighted nymph tied about 8-10 inches off the back. Most often than not those are the very large and wise Trout that "know" that they don't have to waste energy on the duns when they could gorge themselves on the more vulnerable nymphs trying to emerge in the film or under the surface! Remember to be very observant to the specific fish you're going to cast to. One may be sipping, the other splashing and yet another bulging right under the surface.

When fishing Sulphurs, keep in the back of your mind the possibility of the "masking hatch" when you have tried everything and you still come up short. This is normally because of another mayfly that you have not noticed due to its size, the Pseudocloen, also known as the tiny Blue Winged Olive, size 20-26. This has happened to me on a number of occasions. Keep a sharp eye out, especially on cloudy evenings.

Still fresh in my mind from last season I remember when my brother and I were fishing the Missouri River in Montana during a great PMD hatch. The two of us were skunked for two hours and totally frustrated because Trout were rising everywhere and the PMD'S were blanketing the water but no trout were being caught. At the time I thought the masking hatch were Caddis flies, but it was not! Later that winter as I was booking my trip for this coming season, I mentioned to the owner of the Missouri River Trout Shop what had happened to us last season. He said, "They were probably taking pseudos." I just laughed to myself because I thought the psuedos were done hatching at that time of the year. Instead of thinking I should have looked closer!

Finally, the Imago-spinners. The Dorothea spinners are the same size as the adults size 16-20 with yellow brown body color and clear wings. The Invaria spinners are size 12/14 with the same body and wing coloration of the Dorothea. Both species like most will lay their eggs at the most comfortable part of the day, look for them in highly concentrated swarms over the riffles. Earlier in the season you may see them between 6:00 - 7:00 p.m. As the season progresses and it gets warmer, look for them right at dusk or after dark. I personally have seen them after midnight with a real heatwave upon us. Be very observant to the rise forms and try to determine if the fish are eating the spinners or are they still feeding on the duns. An invaluable tool for this and many other situations, day or night, while trying to determine what insects are on the water is a seine net and/or a butterfly net. At dusk and after dark, a mini mag light can save the day when trying to look at what insects are in your net. Before dark I cast the spinners the same way I do the adults, down and across. Spent spinners after mating and egg laying, fall onto the streams surface with their wings spread out on the water sit motionless while waiting to die. Most times you will have sipping type rises associated with this activity.

While casting to the sippers or faint rises during the Dorothea hatch, I start with a cripple pattern or spent spinner pattern.  I also like to use a comparadun or parachute pattern with a cripple or spinner pattern tied in tandem 12-18 inches behind the lead fly. Keep in mind that the tandem setup doesn't always work as well with lower water or with "mini-currents". It's hard enough to get a drag free drift with one fly, let alone two. At that point I work each pattern alone until success.

A little about 'semi spent spinners'. When the Imagos are laying their eggs over the stream, they sometimes land on the surface because of wind, or because they have finished their "business" and fall to the surface to die. They sometimes get a last bit of life into their wings which causes a real commotion on the surface. With this activity on the surface, you will typically see splashy or smashing rises.

Once darkness settles in, I shorten my leader to about 6-7 feet long. I make short casts up, down, and across stream. This type of fishing after dark is a "feel 'em" take the fly technique. It can be difficult at first, but with some practice and patience it can be extremely rewarding!! Most of the time when it's dark, I fish the spinner about 8 inches behind a very large 4 (4xlong) stonefly or a size 6-10 white wulf pattern. Be careful after dark, know the area you're fishing and never go in over the knees! Good luck and tight lines.

-JOE.T.

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