Wasps build their nests of mud in lofty places, and make wax: hornets, on the other hand, build in holes or in the hollows of trees. With these two kinds the cells are also hexagonal, but, in other respects, though made of the bark of trees, they strongly resemble the substance of a spider’s web. Their young are found at irregular intervals, and are of unshapely appearance; while one is able to fly, another is still a mere pupa, and a third only in the maggot state. The wasp which is kn............