The Green River below Flaming Gorge Reservoir has become famous over the last several years. Good regulations combined with a healthy ecosystem have made the fish population as high as in any stream in the nation despite heavy fishing pressure. The trout feed on the abundant food in the river such as scuds, mayflies, leeches, caddie, midges and terrestrial insects like the ant, beetle or grasshopper. However, even with all these food types there is one food that drives the normally cautious trout out of their minds. This food is, of course, the cicada. Not even the famoussalmonfly or drake hatches of Idaho and Montana can compare to the way trout respond to cicadas.
Lots of people have been fishing cicadas for years and the fish have become suspicious of imitations but they love the big bugs so much that they still cannot resist a well presented fly. Trout seem to prefer cicadas to all other foods, when they are available.
When trout feed on a particular insect, each fish has that insect on a list of preferred foods. One trout might prefer ants to mayflies and another might prefer aquatic redworms to scuds but most fish seem to put cicadas on the top of their lists.
I've been told that trout like the tangy taste of ants above most aquatic insects but I believe that they like the taste of cicadas just as much and cicadas are 100 times bigger. A trout's life hangs on the balance between how much calorie intake he can have over energy output. In other words, a trout can not grow unless he eats more than he needs just to survive. Ants and many small insects have a small number of calories and consequently, lots of them must be eaten for the trout to remain healthy. A single cicada, on the other hand, provides enough calories to last quite a while. Not only are cicadas good for growth but they taste good too, at least that's the way it seems. Either way, trout go buggy over the sight of cicadas.
Cicadas are misunderstood as a rule, not because they are complicated creatures but because their life cycle differs from the regular aquatic insects we normally imitate. First of all, cicadas are not really aquatic insects at all. The adult females bore holes in twigs of trees and lay their eggs. When the eggs hatch, the larvae drop to the ground where they bore into the moist roots of the trees and other plants where they live on plant juices until they are ready to hatch into adults.
There are at least 3 types of cicadas that hatch on the Green River and there are many other types that exist around the world. The most plentiful cicada on the Green has a 3 year life cycle. It is black with yellowish markings and has clear, veined, tent shaped wings with darker edges. Their bodies are shorter and thicker than the typical large grasshopper and they have pointed abdomens. Even though they have a 3 year cycle, the emergences are staggered so generally there are hatches every year. Large black stoneflyes have a similar life cycle, emerging in 3-5 years.
A very fat, yellow cicada hatches on occasion but is not nearly as plentiful and seems to hatch below Little Hole more than from there to the dam. Its body is thicker than the other cicada but not much longer. It has a 7 year life cycle and does not hatch every year. Because the yellow cicada doesn't hatch in large numbers, it is not important in most fishing situations.
The largest of the Green River cicadas has a body that is black with some orange trim on the wings and head. Its body is at least 3 times as big as the other black cicada, almost as big as your thumb. This variety takes 17 years to mature but has many broods, allowing them to hatch almost every year. It is a big bug and takes a good sized trout to even eat it. They are often called Periodical Locusts in many areas.
For sake of clarity, and because I don't know the proper names of each cicada, I'll refer to the first one as the little cicada, the second as the medium (or yellow) cicada and the last as the big cicada. They are of the Order Hemiptera—Suborder 1 lomoptera—Family Cicadidae but I haven't identified individual species. For me "big cicada" and 'little cicada" is close enough and the fish don't seem to be put off by my ignorance anyway.
The adults generally emerge at night then remain in vegetation until their wings dry in the daytime heat. The males are the only ones that make the shrill sound that you hear in the trees during warm summer days. Their abdomen is used as a drum and the noise (music) is designed to attract a female.
Cicadas are poor fliers and are often likened to out-of-control B-52s. Their flights often take them over the river where they land with an unceremoniously loud plop. Fish have very good hearing and even better feel. Once they recognize the "plop," they home right in on that sound every time.
Cicada emergences generally occur from the end of May until mid-July. On warm breezy days, many cicadas end up on the water where trout gobble them up eagerly. This is where you come in. Most traditional trout flies don't have the bulk needed to imitate cicadas so there have been a number of goshawful patterns invented. The first to gain popularity on the Green was the Rio Grande Trude, which lots of people fished without knowing why it worked so well. Next was the Tar Baby, brainchild of Alan Wooly, a guide on the Green River. This used black macrame cord for the body. It worked well but tended to sink after a few fish. Many people now fish with a foam-bodied cicada pattern such as Edge Waters Rubbug. Closed cell foam will float all day and is easy to shape into the cicada form. With a calf tail or elk hair wing and rubber legs, it will work in many streams as an attractor fly.
Big cicadas are not as abundant as the little cicadas but they have the bulk to bring up a really big trout. The bigger brown trout especially like the big cicadas. For general fishing, use the small cicada in about a size 10. The larger fly is often tied on a size 4 hook.
Even though trout often throw themselves at cicada patterns like they are trying to commit suicide, after being caught and released a few times they become much more cautious and will actually test the fly to see if it's real. Some trout will rise to a fly and stop just under it, where their vision is best. Many anglers cannot stand it and set the hook. Other fish will look at the fly and then turn away. Most fishermen take that as a rejection and recast the fly. The fish just got his answer. If the angler had left the fly on the water, the trout would have probably returned to take the fly. This testing of flies may seem like very smart actions but are actually just survival mechanisms acquired through conditioned response.
The trout see flies every day and they come to know that certain actions are either rewarded or punished. The survival instinct tells them to seek only the rewards and avoid mistakes.
Other wary fish will take a fly all the way under, with their mouth open. If the angler sets the hook too fast, the fly seldom finds it's target. Many trout try to sink the fly with the side of their head, then turn and take the fly underwater. All these actions suggest that anglers should wait longer than their reactions want them to so the fish has time to turn completely under and close its mouth on the fly.
Waiting too long means a rejection, because the bug doesn't taste right. It takes practice to know the ideal time to strike but if you tell yourself to wait until the count of three to strike, you'll hook many more fish Think: Slurp, one, two, strike!
Presentation is also very important. Trout in waters as heavily fished as the Green River have come to know that a dragging fly is dangerous and is to be avoided. Keep several "S" curves of line on the water to allow a natural drift. Because trout will often watch a fly for 10 to 30 feet before taking it, long drag-free drifts are best. Naturally there are the fish that streak and hit the fly as soon as it lands but that happens lessoften as the season progresses.
One type of trout is what I call a nibbler. He rises and just kind of nibbles the legs or tail to see if it tastes real. Most anglers set the hook on these fish, usually missing the fish completely. It takes steady nerves but you must wait until you're sure the fish has taken the fly completely under. If your line starts to drag while you're waiting for that kind of trout to take, he'll usually reject it completely. If this happens, change patterns and cast to that fish again. He'll usually come up for another look.
An interesting phenomon that happens after the cicadas are actually gone is called the artificial hatch. Anglers keep fishing cicadas and the fish keep reacting to them as something natural. They "remember" the hatch and the fly triggers a response. Exact patterns become less effective but attractor patterns get good responses. The fish become more and more selective but when they're in an opportunistic mood they will still grab a cicada or an attractor like a big Royal Wulff.
Other fish are triggered by the cicada but reject it at close inspection. When this happens a lot, try dropping a small nymph below the cicada on a 2-4 foot tippet. Trout often reject the cicada and as they turn, see the nymph and take it. The cicada becomes an excellent strike indicator and you should set the hook quickly if the cicada twitches.
As you can see, there is more to cicada fishing than just throwing it on the water (although many fish are caught that way). Most of all, however, cicada fishing is just plain fun. Cicadas are generally easy to see and the sight of a big trout attacking a cicada is really exciting. When conditions are right, the hits come readily and consistently. If you want to brave the crowds in June through the summer, cicadas should be in your fly box.