John Sliwko, age 10, of Albany, N.Y., for his question:

HOW MANY EYES HAS THE NORMAL HOUSEFLY?

The normal housefly is such an expert dodger that she seems to have eyes in the back of her head. Actually she has five eyes, cunningly placed to show glimpses from all directions. She has two big, bun shaped eyes, one on each side of her head. These are compound eyes, and each one is crowded with about 4,000 six sided lenses. The other three are tiny, simplified eyes, arranged in a triangle on the top of her head. Her five eyes work together to glimpse what goes on in front and behind, above and on both sides.