Have you been experiencing ringing in your ears? Don't worry - this time of year it's probably just the song of the Dog Day Cicada. We continue our Bugs of Summer Blog Series with a post featuring this summer time singer. What's all the noise about? Turns out that much like the rest of us, this ugly bug is just looking for love!
by W.S. Cranshaw and B. Kondratieff
Cicadas are probably best known for their buzzing and clicking noises, which can be amplified by multitudes of insects into an overpowering hum. Male cicadas "sing" to attract females. Many produce loud, shrill buzzing noises with vibrating membranes on their abdomens. The sounds vary widely and some species are more musical than others. Though cicada noises may sound alike to humans, the insects use different calls to express alarm or attract mates.
Cicadas are the large insects in the order Homoptera, which includes other sap-sucking groups such as leafhoppers, aphids and spittlebugs. Although abundant, cicadas are far more often heard than seen. Males make a variety of sounds to attract females. Most commonly heard are loud, often shrill, buzzing, sometimes with several individual insects synchronizing their songs. Other cicadas make clicking noises.
Despite their large size, cicadas cause little injury. The immature stages (nymphs) develop slowly underground. They feed on roots but cause no detectable harm to the plants. The greatest injury occurs when large numbers of certain cicadas insert eggs into stems of trees and shrubs. This egg laying injury can cause some twig dieback.
Cicadas are sometimes mistakenly called locusts, a term properly used to describe certain migratory grasshoppers. This error originated when early European settlers encountered large instances of periodical cicadas in the Northeast. As they had not previously seen cicada outbreaks, they likened them to the locusts described in the Bible.
Life History and Habits
Cicada nymphs develop underground, feeding on root sap of various trees and shrubs. The nymphs are generally pale brown, rather hunch-backed, and have stout forelegs they use to dig through soil. Development likely takes between two to five years to complete. Periodical cicadas, Magicicada species, such as the 17-year and 13-year "locusts," are the longest-lived cicadas. They emerge during synchronized periods, often in spectacular numbers, every 17th or 13th year, respectively.
When full-grown, nymphs emerge from the soil. They crawl up a nearby plant or wall, and the nymphal skin splits along the back. The adults pull themselves from the old skin and hang from the plant for several hours, pumping blood to extend the wings. The new exoskeleton hardens and darkens rapidly and the insects then fly away, leaving behind their cast nymphal skins.
Male cicadas attract females by their characteristic songs. Most cicadas have a pair of tymbals or domed, drum-like organs on the sides of the abdomen. They alternately contract and release muscles to make the tymbals resonate. A large air sac in the abdomen with a thin exterior eardrum acts as an echo chamber that greatly amplifies the sound.
The dog day cicada emerges each year in mid-summer. Adults are present for about four to six weeks following emergence. After mating, the adult females begin to lay eggs in slits in the twigs of various hosts. Upon hatching, nymphs drop to the ground, burrow beneath the soil surface, and spend the next two to five years feeding on plant roots. The insect's amazing lifestyle has been a source of fascination since ancient times. Several cultures, such as the ancient Chinese, regarded these insects as powerful symbols of rebirth.
Natural Enemies of Cicadas
Cicadas have several natural enemies, many with unusual habits. Perhaps most spectacular are the cicada killer wasps (Sphecious speciosus) that look like huge yellowjackets and attack the large dog-day cicadas. Other hunting wasps attack smaller cicadas, using paralyzed cicadas to provision nests dug in soil.(Information from the Colorado State University Cooperative Extension)
Stay tuned for Part 2 - The Cicada Killer.
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