Here's why:

* Number of species: Insects make up the vast majority of arthropod species, with an estimated 90% or more of all known arthropod species being insects.

* Population size: The sheer number of individual insects on Earth is mind-bogglingly large, far exceeding any other arthropod group.

While other groups like crustaceans, arachnids, and myriapods are also diverse and important, insects dominate the arthropod world in terms of both species diversity and sheer population size.