Paul Mulcahy, age 10, of Cape Elizabeth, Maine, for his question:

Whv are insects so small?

The most important working parts of a human or an animal body are the insides. The blood stream and the various necessary organs must be shielded by a skin or some other protective jacket. This outer covering also holds the body in shape and helps to keep the internal organs in their proper places. The human body, however, needs more than its pliable skin to hold all of its parts in human shape. It needs a bony skeleton to hold itself up straight and to support the moveable muscles of its arms and legs. Its heart and other central organs are so heavy that they need the support of a bony cage of ribs.

All the sizeable animals need internal skeletons of this sort. But the insects have no bones inside their bodies. They depend on coats of crisp shell or leathery skin to hold themselves in shape. These outer skeletons are tough, but not tough enough to hold a lot of large, soft organs in their proper places. This is why the insects must always remain small, light weight animals. So don't let anyone scare you with the notion of monstrous bugs taking over the world. With no internal skeletons to support their bodies, bugs must stay small. And if bugs ever invent internal skeletons for themselves, they will no longer be bugs.