Full Breakdown
Cicadas Navigate to Trees Using Darkness Cues
4/2/2026, 11:55:04 PM
Precision Movement of Cicadas
Recent research published in the American Naturalist reveals that periodical cicadas, specifically Brood XIII, exhibit a remarkable ability to navigate toward trees by utilizing darkness cues. After spending 17 years underground, these cicadas emerge simultaneously and demonstrate a precise movement toward tree trunks, guided by their ability to detect dark shapes against lighter backgrounds. Martha Weiss, an evolutionary ecologist at Georgetown University, noted that the cicadas' trajectories deviated only slightly from the most direct route to the trees.
Mechanism of Navigation
The study conducted by Weiss and her team involved temporarily obscuring the compound eyes and light-sensing organs of newly emerged cicada nymphs. The results showed that those without visual cues wandered aimlessly and failed to reach tree trunks, while control nymphs with unobstructed vision moved directly toward the trees. This behavior, known as skototaxis, was further confirmed through a visual-preference test where the majority of cicadas crawled toward darker surfaces, demonstrating their instinctual response to darkness.
Broader Implications of Skototaxis
The findings on cicadas contribute to a growing understanding of skototaxis, a behavior observed in various insects. Gene Kritsky, an entomologist at Mount St. Joseph University, acknowledged that while he had observed this instinct in cicadas, the formal investigation into it was previously overlooked. The concept of skototaxis is not limited to cicadas; it has been noted in other insects such as crickets, beetles, and ants.
Related Research on Skototaxis
In a related study earlier this year, entomologist Zach Huang from Michigan State University reported that honeybees and mason bees stranded on water also swim toward darker areas, indicating that skototaxis may be a widespread survival strategy among various species. Huang expressed surprise at the existence of the term "skototaxis" and suggested that this behavior might be more common in the animal kingdom than previously recognized.
Conclusion
The research on cicadas not only sheds light on their unique navigation methods but also opens up discussions about the broader implications of skototaxis in the animal kingdom. As various species demonstrate similar behaviors, it becomes evident that following shadows may be a critical survival strategy across different environments.
