Insects are by any standard a successful group of organisms. Biologists estimate as many as thirty million (!!) species worldwide, of which only a million have been named. Some authors estimate that about 1018 individual insects are present on the earth. The diagram below is a crude visualization of the enormity of the Class Insecta compared with all of the other groups of organisms on the earth. Furthermore, consider that there are many species of insects that have yet to be described, or even discovered, so that any estimate of numbers of species must be regarded as conservative.