Leeches Don’t Fall From Trees: Children’s Discovery of Western Japan Becomes a Praised Book

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Children investigate whether leeches fall from trees in June 2017. (Photo courtesy of Dairyo Higuchi)

INABE, Mie – A book debunking the myth that leeches fall from trees through research and experiments by elementary and middle school students has been enthusiastically received since its publication in September 2021.

Positive reviews for “Hiru wa Ki kara Ochite Konai” (Leeches Don’t Fall From Trees), published by Yama-Kei Publishers Co. Ltd., include, “I was amazed at the curious minds of the children.”

The Kodomo Yamabiru Kenkyu-kai (Children’s Land Leech Study Group) in Inabe City, Mie Prefecture studies the enigmatic ecology of land leeches. It was created about 10 years ago after the experience of a former elementary school teacher, Dairyo Higuchi, 75, when he was a temporary nature study instructor.

It was how children overcame their initial distaste for land leeches to the point that their eyes twinkled as they learned to catch them. This made him think he could use the leeches as teaching aids, an idea that led him to become the group’s coordinator.






Children’s ground leech study group coordinator Dairyo Higuchi holds the book “Hiru wa Ki kara Ochite Konai” (Leeches don’t fall from trees), Dec. 12, 2021. (Mainichi/Noriyoshi Matsumoto)

They started in 2015 with research to find out if leeches really fall from trees. This is based on a common belief that leeches sense the presence of people and fall from above, as many people walking in the mountains end up with the creatures sucking blood from their necks and backs. But no one had ever seen leeches fall from trees.

In an experiment designed to test popular belief, researchers laid a blue tarp on the ground in an area with trees above and waited patiently for a grave. But regardless of the sun or the rain and even the location, none fell. The researchers even tried to see if the leeches climbed trees, but found no evidence. Finally, they were convinced when a researcher sacrificed their bodies to capture video of leeches jumping from their feet to their necks in as little as a few minutes.

Among those waiting for one was Yuta Usui, a second-year high school student and member of the group for five years. He had never even touched a leech before joining the group and said he was drawn to the group because “it’s fun to find questions and answers on my own”.






Yuta Usui, left, and Riku Shimizu observe leeches in a container in Inabe City, Mie Prefecture on Dec. 12, 2021. (Mainichi/Noriyoshi Matsumoto)

Several years ago, Higuchi published the results of the group’s research online. This led to the publication of the book about their activities. The group deals with various themes, including whether deer really scatter leeches, and the children’s struggles to solve these mysteries through trial and error are vividly portrayed.

Higuchi recalls, “At first I thought we would run out of research topics in about three years, but the more we did, the more questions kept coming up.”

In Amazon’s reviews section of the book, readers left comments including: “Climbers are convinced they (leeches) fall from trees, but this was an eye opener”, “It’s amazing what that study subjects can excite children so much!” and “Can’t we have that kind of experience in school?” Some also emailed their praise.






A member of the study group dissects a leech in August 2018. (Photo courtesy of Dairyo Higuchi)

The group’s current research focus is leech spawning, as mentioned in the last chapter of the book. Riku Shimizu, a two-year-old member in their second year of middle school, is among those interested in the subject.

“I saw photos of the group’s (leech) eggs and thought they were beautiful, so I wanted to study them. My ultimate goal is to photograph the moment they lay their eggs,” Shimizu said.

The group continues to collect leachate for research purposes by traveling to the foot of Mount Suzuka for two-day, one-night weekend camps. “I hope this book will help people feel the excitement of real research, which is different from school classes where conclusions come first,” Higuchi said.

(Japanese original by Noriyoshi Matsumoto, Yokkaichi Office)

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