We are determined to see moral qualities in nature. We might describe a hero as lionhearted, but a villain as a snake or a rat. Or an insect. Insects are generally regarded as bad creatures. They sting, bite, spread disease, and eat our homes and food. Of course, they are no more bad than lambs are bad. They are simply doing what evolution has equipped them to do. It can be argued that they are not good, too, but in _What Good Are Bugs? Insects in the Web of Life_ (Harvard), entomologist Gilbert Waldbauer makes the case that as far as making the natural world go around, insects are very good indeed. In fact, he calculates that only about 1.5% of the known insects do us any harm, and a very much smaller percent of the total insects do so, since we have only identified about a tenth of them all, and are better at identifying the pests. Waldbauer, who is professor emeritus of entomology and in this book reflects on decades of loving interest in his subject, says that without insects "...virtually all the terrestrial ecosystems on earth... would unravel." His book, usefully organized with each chapter about a particular activity that insects perform, makes an entertaining and convincing case. We could not have evolved ourselves without insects, and could not keep living if they were to disappear.
It is not surprising that Waldbauer's first chapter is about pollination. Most people know that insects are the pollinators of many flowers and other plants, but people didn't always know this. Pretty flowers were said to be merely a manifestation of God's eagerness to give us pleasure. It was only in 1793 that an observer wrote about flowers, scent, and nectar as a lures for insects, and the discovery that the plants could not be fertilized without them. Most of the plants we eat are fertilized by insects. Insects also help plants by spreading their seeds, thus keeping sibling plants from breeding with each other and spreading the range of the plants. Dung beetles roll the seeds away, locusts carry undigested seeds in their guts, and ants and termites bring seeds into their nests. Ants also protect plants; a species of ant lives on the acacia tree and when these ants smell a mammal, they go on alert ready to sting anything that would take a nibble of a leaf. They also clear out the plants that live nearby which would compete for the acacia's nutrients. Insects directly help animals, besides being food for them. Many birds bathe in ants ("anting") to get their mites and lice eaten away. Ants protect birds in particular trees, and other birds deliberately make their homes near wasp nests. Insects do harm plants and animals, but in Waldbauer's larger evolutionary view, this is merely a limitation of population growth, a prevention of a species burning out in uncontrolled profusion. Harvester ants, for instance, compete with rodents for seeds, and thus keep the rodent population down. Insects are vital in the role of cleaning up. They clean up dead flesh, manure, and dead plants. Bacteria are the ultimate decomposers, but they cannot work on rough plant litter. Once the litter has passed through the guts of maggots, springtails, termites, and others, bacteria and fungi can go to work on it, turning it back into soil.
The action of termites simply shows why we think them bad. Termites do nothing except make a living off dead wood, as they have always done. We are the ones that have turned things topsy-turvy by valuing dead wood in our buildings. Waldbauer's book is hugely valuable in taking this larger view of fascinating fellow creatures. It gives many instances of clever experiments that entomologists have done, bothering the bugs until they give up their secrets. It provides countless examples of evolutionary design that is intricate, even witty. For instance, the botfly has to get its eggs deposited onto a mammal for them to develop, but the female never has to worry about getting swatted; she catches a fly or mosquito, glues her eggs to it, and releases it. The botfly larvae know to pop out when they are delivered to a warm-blooded animal. The book's many examples of this kind can only increase one's admiration for the clever humans who have figured out such things, and for the intricate ways insects have adapted themselves to become a cornerstone of all our planet's life.