Entomologists, if humans have “described and named” some one million different insect species, where do the huge estimates of the total number of insect species come from?

Question

I know they’re small creatures, harder to find than, for instance, all the different kinds of buffalo, but I’ve never seen any scientific reason for why we assume them to be so diverse (up to 5.5 million different species), or why we haven’t found more of them if that’s true. In addition, both the number of estimated species and the total insect biomass (half of all animal biomass on earth, ~1 gigaton) seems . . . I don’t know, difficult to contemplate, visualize? What am I missing here? Are there really that many insects in the world?

In: Biology

Answer 1

Find every insect in one place, check how many species you get.

Repeat that with many more places, while keeping track how much overlap there is (species found in multiple places).

Apply a lot of mathematics to estimate the number of species that can only be found in one place, the number of species that can be found in a few places, and species that can be found in tons of places.

Many of the known species only exist in very small regions. We are confident the regions that haven’t been searched yet will also have many similar species.