Can you tell me which Sefarim mention the Agadah on 16a seven lines from the bottom, about "Bardelos"?
zol zayin gebentched and a giten erev shabbos
C. Fried, Manheim PA
Rabeinu Chananel quotes a Yerushalmi that states "Hash-m transmutes [many of] the beings of His world every seven years..." - I suppose that is a Shemitah-like phenomenon, to show Who is the Boss.
Ben Yehoyada explains that any living being that dies decays and turns into (or attracts) maggots. The Gemara means that the maggots that prey on the remains of a Bardelos look like bats, and those that prey on the carcass of an Arpad look like a Kimosh etc.
Hagahos Ya'avetz, on the other hand, likens the transformations of the Gemara to the metamorphosis of live insects during larval stages or of caterpillars when turning into butterflies.
Best wishes,
Mordecai Kornfeld