The Largest Family

INSECTS by Ross E. Hutchins, 324 pages, Prentice-Hall. $6.95.

Bugs are little, and easy to look down on. Ever since Charles Darwin decided that man and his almighty brain were winning the amoral marathon of evolution, it has been fashionable to pity the poor insects for entering a blind alley of biology that mammalry was smart enough to miss. To promote a larger sense of reality, Entomologist Ross E. Hutchins in this unusually competent volume of popular science invites the reader to climb modestly down the Tree of Life and to shinny out on a branch of evolution unimaginably larger and in many respects more fruitful than his own.

The insect family, says Dr. Hutchins, is the largest of the animal kingdom. It includes nearly a million species that range in habitat from Antarctic snows to petroleum pools, and vary in size from a fairy fly, which measures about one-hundredth of an inch, to an African goliath beetle, which weighs up to 3.4 oz. and walks around eating bananas, which it peels with its snout.

In strength, insects are incommensurable with mammals; their muscle strands are relatively shorter and more numerous. A highly trained human athlete can expend energy at 20 times his basic metabolic rate, but only for a brief period; any old insect can raise the rate to 50, and keep it up for hours. It is no trick at all for a large African grasshopper to catch and kill a mouse, and giant water bugs commonly capture and devour small snakes. Almost any beetle can lift 850 times its own weight; to do as much, a man would have to lift 62 tons. And the common flea, which measures one-tenth of an inch, can jump twelve inches, or 120 times its own length; to do as much, a man would have to jump 720 feet.

Insects surpass mammals, as a matter of fact, in general biological efficiency.

Their breathing apparatus--a system of tracheae that wander through the body like arteries of air--feeds oxygen to the organs up to 431 times as fast as lungs do. Their circulatory system frequently includes a mechanism that reverses blood flow when a clot obstructs the heart. A male moth's numerous "noses" are so keen that he can smell a female more than a mile away. And as for sex, insects hold the patents on mass reproduction. The East African queen termite lays 43,000 eggs a day, and in a single summer two common houseflies can multiply into 190,000,000,000,000,000,000 irritating insects.

Dr. Hutchins further demonstrates that insect instinct is a form of intelligence that often rivals human reason. Prompted by instinct, insects perfected flight 100 million years before the pterodactyl; wasps manufacture paper for their nests and fireflies produce cold light; ants in their wanderings use celestial navigation, and the dragonfly nymph is jet-propelled: when pursued by a predator, it draws water into its rectum and forcibly expels it to make a jetaway. Some insect predators are cunning devils. There is an East Indian bug that captures ants by pretending to be a plant. Attracted by a honeyed tuft of bright red hair on the predator's abdomen, the victim takes a lick, falls down drugged and is promptly punctured and sucked dry. In other matters, however, ants are far from stupid. They practice husbandry and agriculture--some species keep herds of aphids and others grow subterraneous gardens of fungi. And there is one species of wasp that has even learned how to use a tool: it trowels the sides of its earthen house with a pebble.

On page 268, however, Dr. Hutchins is forced to admit, reluctantly, that insects are sometimes terribly silly about sex. The bloom of the Ophrys orchid, for example, so closely resembles the female wasp of the Scolia genus that the male wasp cannot tell the difference and spends most of the day mating merrily with one blossom after another. In the process, pollen is transferred and the orchids multiply, Dr. Hutchins reports; but the neglected female remains waspish.

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