There are some insects which have two wings, flies, for instance; others, again, have four, like the bee. The wings of the grasshopper are membranous. Those insects which are armed with a sting in the abdomen, have four wings. None of those which have a sting in the mouth, have more than two wings. The former have received the sting for the purpose of defending themselves, the latter for the supplying of their wants. If pulled from off the body, the wings of an insect will not grow again; no insect which has a sting inserted in its body, has two wings only.