Ten-Year-Old Jo Nagai Shows Butterfly Memories Survive Metamorphosis and Pass to Descendants

Elementary-school student Jo Nagai designed an experiment in which swallowtail caterpillars were conditioned to associate a mild electronic pulse from a muscle-therapy device with the scent of lavender oil. After pupation, the resulting butterflies were tested in a Y-shaped maze; the trained group overwhelmingly avoided the lavender arm, while an untrained control group split evenly. When the trained butterflies reproduced, their offspring—and the subsequent generation—also avoided lavender despite never receiving the original vibration training. The results provide direct evidence that sense-based memories can persist through the radical reorganization of the body and brain during metamorphosis and be inherited by later generations.

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Seeking scientific guidance, Jo contacted Dr. Martha Weiss, a Georgetown University entomologist who had previously explored memory retention in moths. Dr. Weiss responded enthusiastically, establishing a cross-continental mentorship that enabled Jo to adapt laboratory protocols into a child-friendly, home-based setup. Using simple household items—lavender oil, a muscle-therapy device, and a Y-tube maze—Jo created both a trained cohort and a control cohort of caterpillars, ensuring the experiment met basic scientific standards.

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In 2024 Jo presented the findings at the International Congress of Entomology in Kobe, Japan. Dr. Weiss traveled to the conference to meet Jo and brief global experts, including the Crown Prince of Japan. The collaboration was later discussed on the Signal Hill podcast, where Dr. Weiss highlighted Jo’s future aspirations.

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Dr. Weiss noted Jo’s personal goals, stating, “He told me he doesn’t actually want to be an entomologist when he grows up. He wants to be a veterinarian.” The article’s conclusion added that Jo’s “desire to learn more about animals has only made Jo care even more about them. No doubt he will make a wonderful vet someday.”

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“He told me he doesn’t actually want to be an entomologist when he grows up. He wants to be a veterinarian.” — Dr. Martha Weiss, entomologist, Georgetown University

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