Mary Ann Juranitch, age 11, of Milwaukee, Wisc., for her question:

Is it true that a spider is not an insect?

Chances are, your Board of health classifies the spider along with assorted insects and other small creatures that should not make their homes in the human household But a biologist is quite firm in his opinion that the spider is not an insect.

It is true that the spider and the insects are all classified in the phylum Arthropoda, a word meaning the jointed footed animals. But crabs and lobsters also are arthropods. None of these creatures are closely related to Each other. A true insect has six legs, a spider has Eight. Most insects have four wings, no spider has wings. The body of an insect has three distinct sections, the body of a spider has only two.