English Dictionary

periodical cicada

noun

Any of certain species of cicadas, especially in genus Magicicada, which are known for their 17- and 13-year life-cycles, during most of which they develop underground, emerging in large numbers for a short time as large and audible adults, all those emerging in a year constituting a brood.

The periodical cicada emerges from the ground every 17 years.

意味（1）

Any of certain species of cicadas, especially in genus Magicicada, which are known for their 17- and 13-year life-cycles, during most of which they develop underground, emerging in large numbers for a short time as large and audible adults, all those emerging in a year constituting a brood.

An emergence is when a throng of periodical cicadas rises from the ground as soon as the soil reaches about 64 degrees Fahrenheit. The groups of magicicadas, known as broods, surface only once every 13 or 17 years depending on the species.