John Gill Commentary Leviticus 11:43

"Ye shall not make yourselves abominable with any creeping thing that creepeth, neither shall ye make yourselves unclean with them, that ye should be defiled thereby." — Leviticus 11:43 (ASV)

You shall not make yourselves abominable with any creeping
thing that creeps
With any creeping thing that flies in the air, excepting the four sorts of locusts, (Leviticus 11:22) and with any creeping thing in the waters, (Leviticus 11:10) or with anything that creeps on the land, by eating any of them; which being abominable for food, would make the eater of them so to God, he thereby breaking a command of his:

neither shall you make yourselves unclean with them ;
by touching and bearing them, as with dead beasts, so with dead flies and the like:

that you should be defiled thereby ;
in a ceremonial sense.