Zikaden nutzen Dunkelheitssignale aus den Schatten, um sich auf Bäume zu bewegen | Die als Skototaxis bekannte Fähigkeit, Schatten wahrzunehmen, hilft Zikaden dabei, Bäume zu finden, auf denen sie sich häuten können

When periodical cicadas surface after years underground, they don’t grope blindly for trees. [They head for the shadows](https://www.journals.uchicago.edu/doi/10.1086/741447), researchers report March 20 in the *American Naturalist*.

A detailed analysis of [Brood XIII](https://www.sciencenews.org/article/periodical-cicadas-big-brood-year) cicadas — which spend 17 years developing in [subterranean tunnels](https://www.sciencenews.org/article/mystery-synchrony) before emerging all at once — found that newly arrived, wingless nymphs use darkness cues to move with striking precision toward tree trunks.

Across dozens of recorded trajectories, the insects deviated only slightly from the most direct route. “They just zoomed in, marching toward the trees,” says Martha Weiss, an evolutionary ecologist at Georgetown University in Washington, D.C.

This near-direct movement, Weiss and her colleagues found, hinges on the cicadas’ ability to detect dark shapes against paler backgrounds in the dim evening light. That cue guides the nymphs to the vertical surfaces they must climb to become winged adults.

[**Read more here**](https://www.sciencenews.org/article/cicadas-climb-trees-shadows?utm_source=Reddit&utm_medium=social&utm_campaign=rmh) **and the** [**research article here**](https://www.journals.uchicago.edu/doi/10.1086/741447)**.**