Worms Wiggle

``Worms . . . wiggle. Bugs . . . jiggle. Frogs . . . leap. Caterpillars . . . creep.'' The simplicity of the imagery that introduces the first few pages of this book continues throughout the remaining text. ``Puppies . . . bounce. Kittens . . . pounce. Lions . . . stalk. But I . . . walk.'' With those few words, and with colorfully illustrated and skillfully executed pop-up paper engineering, Pelham ( The Human Body ) and Foreman have created an appealing pop-up book, though it's somewhat fragile for readers at the younger end of the age range. Ages 4-6. (Feb.)