There are more than 200 million insects for every human being living on the planet today. As you sit reading this sentence, between 1 quadrillion and 10 quadrillion insects are shuffling and crawling and flapping around on the planet, outnumbering the grains of sand on all the world's beaches. Like it or not, they have you surrounded, because Earth is the planet of the insects.
There are so many of them that it's difficult to take it in, and they are everywhere: in forests and lakes, meadows and rivers, tundra and mountains. Stone flies live in the chilly heights of the Himalayas at altitudes of 20,000 feet, while brine flies live in the piping hot springs of Yellowstone National Park, where temperatures exceed 120 degrees Fahrenheit. In the eternal darkness of the world's deepest caverns live blind cave midges. Insects can live in baptismal fonts, computers, oil puddles, and the acid and bile of a horse's stomach. They live in deserts, beneath the ice on frozen seas, in the snow, and in the nostrils of walruses.
Insects live on all continents—although they are admittedly represented by only a single species on Antarctica: a flightless midge that can't survive if the temperature happens to creep up to 50 degrees for any length of time. There are even insects in the sea. Seals and penguins have in their hides various kinds of lice, which remain in place when their hosts dive beneath the surface. And we mustn't forget the lice that live in a pelican's pouch or the water striders who spend their lives scudding six-legged across the open sea.
Insects may be tiny, but their achievements are far from trifling. Long before human beings set foot on this planet, insects had already taken up agriculture and animal husbandry: termites grow fungus for food, while ants keep aphids as dairy cattle. Wasps were the first creatures to make paper from cellulose, and caddis fly larvae were catching other creatures in netlike webs millions of years before we humans managed to weave our first fishing nets. Insects solved complicated problems of aerodynamics and navigation several million years ago and learned if not how to tame fire, at least how to tame light—even within their own bodies.
Whether we opt to count them by individual or species, there are good grounds for claiming that insects are the most successful class of animal on the planet. Not only are there incredible numbers of individual insects, they also account for well over 'half' of all known multicellular species. They come in around a million different variants. This means that you could have an "insect of the month" calendar that featured a new species every single month for more than 80,000 years!
From A to Z, insects impress with their species' richness: ants, bumblebees, cicadas, dragonflies, earwigs, fireflies, grasshoppers, honeybees, inchworms, jewel beetles, katydids, lacewings, mayflies, nits, owl moths, praying mantises, queen butterflies, rice weevils, stink bugs, termites, urania moths, velvet ants, wasps, xylophagous beetles, yellow mealworms, and zebra butterflies.
Let's do a quick thought experiment: to get an impression of how species diversity is distributed among different groups of species, imagine if all the world's known species—big and small alike—were given UN membership. It would be an awfully tight squeeze in the assembly chambers, because even if there were only a single representative for every species, that would still add up to well over 1.5 million representatives.
Let's say we distributed power and voting rights in this "United Nations of biodiversity" according to the number of species in the different species groups. That would create new and unusual patterns, predominantly because insects would dominate, comprising more than half of all votes. And that's before we consider all the other small species, such as spiders, snails, roundworms, and the like, which alone would account for a fifth of the votes. Next up, plant species of all kinds would total roughly 16 percent, broadly speaking, while known species of fungus and lichen would command around 5 percent of votes.
Where do we fit into this picture? When we look at species diversity like this, humanity doesn't amount to much. Even if we were counted along with all the rest of the world's vertebrates—with animals such as elk and mice, fish, birds, snakes, and frogs—we would still end up with a minuscule share of power, constituting a mere 3 percent of known species diversity. In other words, we humans are totally dependent on a host of tiny species, a significant proportion of which are insects.