Leviticus 11:21-23—”Insects like locusts have six legs, not four.”
This is a simple misunderstanding related to translation. First, the locusts listed all have four normal legs plus two very different large hind legs used for jumping—in ancient times these must not have been counted among the walking legs, and thus they are described as “four-legged.” Furthermore, the term “walk on all fours” is an expression which includes any creature walking on four or more legs—insects, millipedes and centipedes.
It may be asked how any “insect” could be described as four-legged, since an insect is by definition six-footed (in English). The answer is simple—the Hebrew term translated ‘insect’ is שׁרץ (sherets) which means simply “tiny swarming creeping creature,” rather like our colloquial term ‘bug.’ Our modern classification of “insect” as six-legged relates to the modern technical English category, not the colloquial Hebrew term.