In Leviticus 11:20-23, it says that insects have four legs instead of the six that we have always learned in school. Does the Bible have a different way of counting the legs of insects?
"All flying insects that creep on all fours shall be an abomination to you. Yet these you may eat of every flying insect that creeps on all fours: those which have jointed legs above their feet with which to leap on the earth. These you may eat: the locust after its kind, the destroying locust after its kind, the cricket after its kind, and the grasshopper after its kind. But all other flying insects which have four feet shall be an abomination to you" (Leviticus 11:20-23).
Taking the class of all creatures which fly, but which walk on four legs -- we understand that God isn't talking about birds (they fly, but have two legs), so He is discussing what we call "insects" today. Yes, insects have six legs, but flying insects have four legs for walking and two other legs which are specialized. A fly, when it walks, uses its back four legs and the front legs are used to bring things up to its head. A grasshopper walks on its front four legs and the back legs are specialized for leaping -- they aren't generally used for walking. The Israelites were allowed to eat leaping, flying insects which were identified by their rear legs being much larger than the four walking legs.
We make no distinction as to what legs are used for. The passage in Leviticus does.