THE ROBINSON LIBRARY
|The Robinson Library >> Insects >> Order Hemiptera|
Cicadas have a broad, flattened body and two pairs of large wings with characteristic pattern of veins. The longitudinal veins do not extend to the edge of the wing but stop short of it, leaving a narrow, uninterrupted margin along the outer border of each wing. The wings are usually transparent, but those of some species are colored and patterned, and when at rest they are folded over the body like a roof.
Some cicadas are among the biggest of all insects and most are quite large. Although the average body length is 1 to 2 inches, the Malaysian empress cicada (Pomponia imperatoria) has a wingspan of 8 inches.
More than 1,500 species of cicada are known throughout the world. They are mainly tropical, extending into the temperate regions in small numbers. A few species occur in southern Europe, and about 75 occur in North America.
Eggs are laid in slits in the twigs of trees. Nymphs fall to the ground after hatching several weeks later, and then dig down with their broad, powerful front legs and disappear underground. They will spend the majority of their lives in a burrows that may anywhere from several inches to a few feet underground, depending on the nymphal stage and nature of the soil.
The duration of the nymphal stage varies by species. Among the longest-living of all insects, many cicada nymphs take 2 to 5 years to develop into an adult, while still others spend 17 years in the nymphal stage. When ready to mature, the nymph digs its way up to the surface and climbs the nearest tree, where it rests before shedding its skin and emerging as an adult cicada. Despite their long lives as nymphs, however, adult cicadas only live 6 to 10 weeks, time they spend eating and mating.
Cicadas belong to an order of insects with piercing and sucking mouthparts. Adults feed on the sap of plant stems and succulent shoots, while nymphs extract sap from roots. The specific types of plants fed upon varies by species and location.
Habits and Behaviors
Adult cicadas spend most of their time sitting high up on the trunks of trees, or among the branches and foliage. When approached they will usually fly off quickly. Their flight is fast and powerful.
All species of cicada "sing," and every species has its own distinct song. Although singing is exclusive to males in most species, there are a few species in which the females also sing. Both sexes have hearing organs, and all cicadas can recognize the song of their species. Some cicadas sing during the day, others only at dusk or dawn; some sing intermittently, while others may sing for extended periods of time. The purpose of the cicada's song is probably to call the local population of a species together for mating purposes.
The singing apparatus consists of a pair of membranes at the base of the abdomen, each surrounded and held by a stiffly elastic ring. The membrane is convex when relaxed, but a muscle attached to it can pull it down and allow it to pop back. The membranes, known as tymbals, oscillate at a rate of 100 to 500 times per second. Other muscles attached to elastic ring distort the ring's shape, affecting the volume and quality of the sound produced. The whole apparatus is enclosed in a pair of resonating chambers which amplify the sound and vary it by opening and closing.
1) Cicade underside showing the
sound-boxes, which are covered by a protective plate (operculum).
2) The cicada's muscular attachment, showing the tymbal's
position in the air cavity which helps amplify the sound.
3) A cross-section through the thorax shows the powerful
muscles attached to the tymbal sound-boxes, which have
concave inner surfaces.
Adult cicada photographed from
below to show sound-box cover.
Library >> Insects >> Order Hemiptera
This page was last updated on June 19, 2018.