The ninth 節気 “sekki” division of the traditional Japanese calendar is:
‘grain beards and seeds’ // ‘grain in ear’ (solar term)
The second “kō” microseason within this division is:
(くされたる くさ ほたる と なる)
“kusaretaru kusa hotaru to naru”
Rotten grass becomes fireflies
That makes 腐草為螢 the twenty-sixth microseason of the year!
It typically lasts 11~15 June.
Image credit: 5 by Mike Lewinski.