Cicadas are part of the Order Hemiptera (formally classified under Order Homoptera) that represents 82,000 categorized species around the globe to which some 12,000 are found in North America alone. Cicadas belong to the same order as "True Bugs" but are differentiated by their rigid mouthparts that attach to the back of the head instead of the front (as in True Bugs). Cicadas emerge in large numbers which in itself can be considered a defense mechanism against predators - if your enemy's stomach is full of your friends, he will not feel the need to try and eat you!
There are a total of 4 Cicada (and Similar) insects in the Insect Identification database. Entries are listed below in alphabetical order.