The word translated insects here is the same as “swarming creatures” in verse 10 and “swarming things” in verse 29. But with the word winged or “flying” added, it is clear that the reference is to insects with wings.

That go upon all fours: this expression is surprising, since the ancient Jews almost certainly knew that winged insects had six legs. The expression was probably used in a nonliteral sense, meaning “to crawl,” and was used of any flying creature with more than two legs, to distinguish the insects from other flying creatures such as the birds just mentioned in the previous verses. Good News Translation has avoided the problem altogether, and other modern versions have omitted the number “four.” Bible en français courant, for example, has “insects which have wings and legs.” In other languages the idea may possibly be rendered “with more than two legs.”

Abomination: see verses 10 and 11.

Quoted with permission from Péter-Contesse, René and Ellington, John. A Handbook on Leviticus. (UBS Helps for Translators). New York: UBS, 1990. For this and other handbooks for translators see here .