Large, stocky insects,
cicadas are best known for the shrill calls of the males, audible for up to
a mile or more. Located on the sides of the first abdominal segment are membranous
areas of the cuticle, called tymbals, which are alternately buckled and restored
by the contraction and relaxation of a large muscle. Each movement of the
tymbals produce a click 
or
pulse, which in a long series constitute the cicada's call, which is a hallmark
of the warm dry days on the Green River of Utah. A complex series of resonating
air sacs present in the abdomen greatly amplifies the call.
Cicadas are dark and fairly large, 16-50mm in length, with prominently veined, membranous wings, the front pair of which are about twice as long as the hind pair. Females lay their eggs in slits made in twigs of trees and shrubs, the tips of which usually die as a result. Upon emerging, nymphs fall to the ground at the base to of the tree where they burrow under the soil with their well-developed fore legs and feed on the xylem sap of plant roots. Because of the low nutrient content of this food, development is slow, and the nymphs will spend the next 4 to 17 years underground, depending upon the species. Occasionally, enormous broods will emerge in the same year, leaving thousands of shed skins still clinging to the individual trees that they climbed for their final molt.
Cicada hunting: Excluding the years when large broods of periodic cicadas emerge simultaneously, these robust insects can be surprisingly hard to spot because of their preference for tall shade trees. Your best chance of finding them is to follow the male's raucous buzz, which swells magnitude and the tapers off toward the end. If you cannot spy the adults, then look for their shed nymphal skins, which are hollow replicas, down to the smallest detail. You will find these still clinging to the bark of the tree trunks where they were abandoned. If you find these, there are almost certain to be burrows at the base of the tree, from which the nymphs emerged. These burrows are roughly 15mm in diameter and show no signs of excavation for the surface, such as loose dirt from the perimeter.
Importance:
The trout on the Green River, rainbows, browns, cutthroats and cutt bows have this very endearing quality of eating big flies. A habit that starts in mid June and continues through September. The insect that is most responsible for getting the trout turned on to big targets is the annual cicada hatch. These are big tree hopper terrestrials that occasionally fall into the water as they mature and mate. It can account for some very exciting fishing on the Green River in late June and July with big dry flies.
Patterns:
Taupo Cicada, Chernobyl Ant, Turk's Tarantula, and Boomer's Cicada in black and tan colors in sizes 6-10.