2021 may be the year of the cicadas. A huge population of cicadas have been living underground since 2004 and are scheduled to emerge within the next few weeks! Cicadas 2021!
What are cicadas?
Cicadas are a group of 3000 different known insect species around the world. The oldest cicada fossils are nearly 300 million years old.
Cicadas have prominent eyes and short antennae. Their front wings are transparent and membranous. Most cicada species are active during the daytime, especially at dawn and dusk.
The largest species is the Malaysian emperor cicada with an 8 inch wingspan but most species are between 1 and 2 inches long. Most cicadas live in tropical regions and nearly all cicada species spend their whole lives in one geographic area. They do not sting, bite, or carry disease.
Cicadas are commonly eaten by birds and sometimes by squirrels, bats, wasps, and other animals which often feast at the time of emergence. Nymphs living underground may be eaten by burrowing mammals such as moles.
Cicadas are among the loudest of all insects
Cicadas are known for their loud song which they produce by vibrating drum-like structures called timbals which resemble corrugated cardboard on the abdomen of male cicadas. The vibrations of the timbals resonate within the hollow abdomen of the male cicada and amplifies the sound. A male cicada can modulate the sound by positioning their abdomen. The sound that a cicada makes can be very loud, possibly even as loud as a lawn mower or motorcycle, and can be heard up to ½ mile away. Male cicadas can temporarily disable their hearing to prevent damage when they are calling. Most cicada species call from trees. Different species may occupy the same tree and call from different heights.
Cicada life cycles
A cicada has three stages in its life cycle – eggs, nymphs, and adults.
The egg part of a cicada’s life cycle lasts 6-10 weeks. After mating, female cicadas cut slits in the bark of twigs and deposit hundreds of eggs into the twig. The adult cicadas die soon after mating. When the eggs hatch, the newly hatched nymphs drop to the ground and burrow into the ground immediately.
Nymph cicadas can not jump but have forelimbs adapted to live underground. They have strong front legs to help with digging. They excavate chambers near roots which provide sap for the nymphs to eat. They can live underground for a long period of time which varies from species to species.
When it is time to emerge, the nymphs dig an exit tunnel to the surface and climb out. Then, they molt into adults, leaving their abandoned exoskeletons on the bark of the trees they were living under. After molting, the adults rest for a day or two then spend the next 3-4 weeks mating. In some species of cicada, the males stay in one place and call to attract females, often in chorus with other males. In other cicada species, the males move from place to place, usually with quieter calls while searching for females.
Different species of cicadas spend different amounts of time underground as nymphs. A brood is a population of cicadas that emerges in a geographical area at the same time and can be predicted based upon their species.
Annual cicadas spend 1-9 years underground as a nymph. A portion of the population emerges each year.
Periodical cicadas are the best known North American species of cicada. It has a 13 or 17 year life cycle. Their emergence is normally very well predicted and quite dramatic. Scientists believe that the long period in which cicadas remain underground helps the species avoid loss to predation since predators will not be able to depend upon them for food. Because so many periodical cicadas emerge at once, predators become sated quickly and later emerging cicadas are safe from predation. 2021 is the year for a cicada population called Brood X to emerge in 15 states of the eastern United States. The cicadas that will be emerging this year were born in 2004. Emergence is normally early to mid-May. An app called Cicada Safari allows observers to record when cicadas are spotted throughout the Country.
Emergence is triggered when the soil temperatures 8 inches underground reaches 64 degrees Fahrenheit. Patterns of emergence dates vary with climate and are considered a marker of climate change since records of cicada emergence date back hundreds of years.
Previous Amazing Animals of the Week: