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 الولايات المتحدة تشهد انتشار مزدوج لحشرات السيكادا infographic
Graphic shows areas where the cicadas are expected to emerge and their life cycle.
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الولايات المتحدة تشهد انتشار مزدوج لحشرات السيكادا

By Jordi Bou

February 21, 2024 - من المقرر أن تخرج المليارات من حشرات السيكادا من مستعمرتي تفقيس (برود) مختلفتين تحت الأرض في حدث متزامن نادر للغاية لم يشاهد منذ 221 عاما.

Brood XIII emerges every 17 years, and Brood XIX has a 13-year cycle.

Both boods last aligned in 1803, when Thomas Jefferson was the U.S. president. The next time is set for 2245.

It’s uncommon but not unheard of for two broods to appear at the same time, but these two are so geographically close that they may overlap and interbreed in some of the woods and fields in Illinois –a potentially exciting rarity for entomologists.

Cicadas do not bite but emit sounds between 80 and 100 decibels, the equivalent to a low flying airplane or a lawn mower.

Scientists believe that huge and synchronised arrival provides protection against predators.

There are more than 3,000 species of cicadas worldwide, but only nine are periodical, and seven of those are found in North America. In India, a periodical species of the genus Chremistica emerges every four years, while in Fiji, a periodical species of the genus Raiataena emerges every eight years.

Sources
PUBLISHED: 21/02/2024; STORY: Graphic News; PICTURES: Newscom, White House Historical Association
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