Bioluminescence.

Yosa Buson: An idle student by the window.
[>> all he can do is glitter in the night.]

He's a firefly:
all he learns escapes
out of his ass !!

All he learns
escapes out of his ass
a firefly, isn't he ?!

Al wat ie leert,
ontsnapt uit zijn reet:
een ware vuurvlieg !!


Translation: 白狐

[YB360]
gakumon wa
shiri kara nukeru
hotaru ka na.

"education (learning) -- [nominative particle] /
ass (buttocks) -- from -- escapes /
firefly -- isn't-he-??"

Source: "Collected Haiku of Yosa Buson",
translated by W.S. Merwin & Takako Lento,

. . . but in my opinion it leaves a lot to be desired !!
Japanese only in Romaji, so no kanji to make sure.