The eighth 節気 “sekki” division of the traditional Japanese calendar is:
‘lesser ripening’ // ‘grain full’ (solar term)
The first “kō” microseason within this division is:
(かいこ おきて くわ を はむ)
“kaiko okite kuwa o hamu”
Silkworms start feasting on mulberry leaves
That makes 蚕起食桑 the twenty-second microseason of the year!
It typically lasts 21~25 May.
Image credit: Educational Science.