How do cicadas know what season it is?

Crowdscience listener Ryosuke grew up in Japan, and spent his childhood summers catching cicadas in the park. For people in Japan, the sound of their chirping signals the first true summer day. But until they emerge, these enigmatic insects live underground - often for many years. Ryosuke wants to know how they know the time is right, and CrowdScience is on the case. Presenter Anand Jagatia pieces together the story of the species, and meets the small but dedicated group of academics worldwide who’ve been able to study them. In a field near Girona, Spain, he meets a scientist who’s spent the last twenty years counting them. How will a temperature probe help us work out when they might emerge, and what are they doing underground for so many years anyway? In nearby Barcelona, another scientist cuts open the stem of a tomato plant and Anand watches as the sap flows out. Could this be a clue to how cicadas sense what’s going on above ground? And he meets a cicada breeder in the US who has discovered a link between the life cycle of cicadas and the fruiting of a peach tree. Armed with that knowledge, can you really make time move faster for tree and insect alike? Presenter: Anand Jagatia Producer: Robbie Wojciechowski Editor: Ben Motley (Photo:Cicada on Hosta Leaf - stock photo Credit: KenWiedemann via Getty Images)

You can listen to How do cicadas know what season it is? online on Radio and Podcast. Open the player on this page to stream the available audio.

How do cicadas know what season it is? is an episode from CrowdScience by BBC.

This episode is 26:29 long.

This episode was published on Jan 9, 2026.

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