From Mar 15, 2026 to Mar 19, 2026, the corresponding solar term in the Nijūshi Sekki (24 solar terms) is 啓蟄(Keichitsu), and the corresponding microseason in the Shichijūni Kō (72 microseasons) is 菜虫化蝶(Namushi cho to naru).

What Is “Namushi cho to naru” (菜虫化蝶)?

"Namushi Chō to Naru" (菜虫化蝶) is one of the Shichijūni Kō (72 microseasons), Japan's traditional system for marking the passage of time, and falls each year around March 15–19. The Shichijūni Kō divides the year into 72 finely observed segments, each capturing a subtle shift in the natural world. "Namushi" (菜虫) refers to the green caterpillar — the larva of the cabbage white butterfly, which feeds on the leaves of brassica plants such as cabbage and daikon radish. "Kachō" (化蝶) means "to transform into a butterfly": having spent the winter as a chrysalis, the caterpillar emerges with the warmth of spring, reborn as a delicate butterfly taking its first flight. This is the threshold of true spring — the plum blossoms have fallen, and the cherry blossom season waits just ahead. Across fields and gardens, cabbage white butterflies begin to drift on the breeze, their pale wings catching the light, and we feel spring's arrival not just in the air, but in our bones. The butterfly — breaking free from its shell after enduring the cold of winter, utterly transformed — has long been cherished as a symbol of renewal and change. The Japanese have always found the turning of seasons in even the smallest of creatures, taking care to name and record each fleeting moment. Embedded in the phrase "Namushi Chō to Naru" is a deep reverence for the workings of nature, and a quiet joy in the life force that stirs each spring. When we attune ourselves to the Shichijūni Kō, we begin to discover the richness of the seasons hidden in the ordinary scenes of daily life. This spring, why not watch a butterfly drift past — and feel the same wonder that people felt, in this same season, long ago?

List of Japan’s 72 Microseasons