Terry L. Erwin

Curator, Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, D.C.

Life on Earth takes many forms and comes in all sizes, from microscopic one-celled plants to blue whales and human beings. Together these organisms and their interactions constitute our planet's biodiversity. Among this profusion of life are the beetles and their insect and arachnomorph relatives, which, taken together, constitute most of Earth's biodiversity (Erwin, 1982; Hammond, 1992; Robinson, 1986; Wilson, 1992). There are 1.4 million species of insects described in the scientific literature (Hammond, 1992), which is about 80% of all life currently recorded on Earth. Taxonomists, those who name and classify species, have been describing species of insects at about 4,400 per year for more than 235 years, and in the last 25 years, have described about 8,680 per year (±363). This written record is at best perhaps only 3.4% of the species actually living on the planet (Erwin, 1983a). Recent estimates of insect species, mostly in tropical forests, indicate that the descriptive process is woefully behind. These estimates indicate there may be as many as 30-50 million species of insects (Erwin, 1982, 1983b), making this pervasive terrestrial arthropod group 97% of global biodiversity. The familiar ants and grasshoppers, bees and beetles, houseflies and cockroaches, and spiders are but the tip of the iceberg of arthropod diversity; most species are small to very small tropical forest-dwelling forms that no one has seen or described on any adequate scale.

Insects and their relatives (spiders, ticks, centipedes, etc.) are the most dominant and important group of terrestrial organisms, besides humans, that affect life on Earth, often with an impact on human life. They affect human life in a multitude of ways—both for good and bad. Profound ignorance about insect life permeates most of human society, even among the highly educated. Insects