Butterflies of the World by Valerio Sbordoni and Saverio Forestiero (Times Books: $39.95; 312 pp.)

One of the sad side-effects of this increasingly paved and polluted planet has been the decline of butterflies. Collectors, who could once swing their nets with great success in suburban gardens, now must content themselves with meager assemblages or mount expeditions to less sprayed and settled country.

On the other hand, the hobby of lepidoptery and the modern synthesis of biological sciences have rediscovered one another. There is still much to be learned of the physiology, ecology, even the distribution of these best beloved of insects. In turn, because they are numerous and visible, butterflies have provided tests for many of the key theories of modern biology while serendipitously inspiring new avenues of investigation. They even serve as excellent monitors of environmental health.

“Butterflies of the World” is handsome evidence that both hobby and science have been enriched by the interchange. It is a remarkable book, quite off the beaten literary path in a number of successful ways. It was written, illustrated and printed by Italians. The book is solidly bound, oversized, on heavy, coated stock. The illustrations are mostly watercolor paintings, comprising fully half the volume. And the authors, both theoretical zoologists, have been translated gracefully from the Italian.

“Butterflies of the World” was designed to seduce the layman: The dazzling array of illustrations invites browsing, provokes curiosity, and leads inexorably to a read of what turns out to be clear and energetic prose. But then . . . what appears superficially to be a lovely book about butterflies reveals its true colors: Sbordoni and Forestiero have produced a comprehensive biology of Lepidoptera certainly the equal of a good college course on the subject.

For example, the authors explore the fascinating business of aposematic--or warning--patterns and coloration, and of mimicry in the butterfly world, in which several unrelated species closely resemble one another. Sometimes this is Batesian mimicry, when an edible species resembles one that is inedible, and so derives protection therefrom. More exciting is Muellerian mimicry, which usually occurs in tropical forests that contain many uncommon species. There, several different inedible butterfly species mimic one another, presumably to reinforce the ‘Don’t eat me!’ signal to potential predators. The signals themselves are the bright colors and striking patterns we find so attractive. Sometimes bright eyespots and wing displays are kept hidden until a predator is about to strike; the sudden flash often startles or disorients, and its owner is able to make his escape.

Of course, many butterflies and moths use their markings as disguise or concealment, resembling--at rest--leaves, twigs, even bird droppings! All of these strategems are, of course, beautifully illustrated with examples from all over the world, and clever black-and-white keys with detailed annotations for each color plate. Better yet, the mechanisms behind these tricks of the trade are explained.

True to the title, this book contains a systematic survey of the moth and butterfly families of the world. Typical examples of each family are illustrated along with diagnoses of families and orders. The pictures are nice, but such a taxonomy is of interest primarily to lepidopterists, amateur or otherwise. Another chapter offers an “ecological distribution,” which explains why the numbers of species and the size of individuals in tropical forests is so much greater than for temperate or arctic biomes, and why butterflies in one habitat feed exclusively on one species of plant, while those in another are more catholic in their tastes. Yet a third section looks at the geographical distribution of Lepidoptera, demonstrating clearly and cleverly how physical barriers such as mountains and oceans regulate dispersal and colonization; why butterflies in one place are sedentary and those in another migrate great distances.

Of greatest delight to this biologist, though, are the frequent excursions into odd corners of ecology, behavior, evolution, and the linkages among those three that illustrate so well how nature repeats the same lessons again and again, for butterflies, for beasts, for humankind. Did you know there is a vampire moth and several troglodytic species, while some butterflies feed on dung? That species are gregarious, living in great colonies, while others are solitary and ornery to their own kind? Whether it is in courtship, defense of territory, or adaptations to local environmental conditions, you can see bits of ourselves in these fragile and short-lived sprites.