The appearance of pests and a pest across the sea strait: The world of the maize weevil

① Ever-increasing maize weevil impressions

In 2005, a maize weevil, known today to be a pest that feeds on cereal grains, was discovered in a Jomon pottery piece. Investigations of Jomon pottery since then have revealed many impressions of maize weevils. Currently, even if we restrict the count to the Jomon period, 800 impressions of maize weevils have been found at approximately 60 archaeological sites, from Tokunoshima in the south to the Oshima Peninsula in Hokkaido in the north. These insects account for over 90% of all insects found in impressions, which is a highly unusual finding.

② Jomon maize weevils did not eat rice

These maize weevils apparently did not eat rice. We believe this is to be the case because they are approximately 1.2 times the size of the maize weevils that did eat rice. These maize weevils, whose size is determined by the size of the seeds they feed on, are thought to have fed on the acorns and chestnuts stored by the Jomon people.

③ The spread of pest insects was caused by the Jomon people (maize weevils that crossed ocean straits)

Impressions of maize weevils have even been discovered at the Tatesaki Archaeological Site at the tip of the Oshima Peninsula of Hokkaido. The size of the maize weevils found on Hokkaido is approximately 20% bigger than that of the maize weevils found in western Japan, indicating that these maize weevils fed on chestnuts. Chestnuts were not originally native to Hokkaido. It is thought that they were brought to Hokkaido by people who dealt with Ento-doki Culture in the Tohoku region of Japan, the location of the famous Sannai-Maruyama Archaeological Site. The impressions found at the Tatesaki site are of maize weevils that crossed the Tsugaru Strait hidden in chestnuts that were transported from the Tohoku region.