Here is a question about nature, and specifically about insects, that I didn’t think to ask until I came on inaturalist and started posting so many pictures of insects!
There are two types of insects. Hemimetabolist, and holometabolist. The hemimetabolist insects hatch (or sometimes are born alive), in a form that pretty much resembles the adult, but smaller, and often without functional wings. A holometabolist animal is born as a larva, usually a worm-shaped one, and lives for a long time as a larva before they pupate and become an adult.
Common hemimetabolist insects are dragonflies, grasshoppers, bugs and aphids, cockroaches and preying mantises.
Common holometabolist animals include four big families: bees and ants, moths and butterflies, beetles and flies.
Hemimetabolist insects are certainly successful, I can walk through a field and see dozens of grasshoppers flying around. But in terms of biomass, species diversity, and shaping the ecosystem, the holometabolist insects are much more successful. (Although maybe that is a matter of judgement…)
So the thing is, holometabolism seems like a much more risky business. Holometabolist insects hatch in one form, live in that form, and then form a vulnerable pupa before becoming an adult. A hemimetabolist insect, on the other hand, hatches and is ready to go, with no intermediate steps. In the case of some aphids, they are born alive and ready to eat. It seems that from an evolutionary standpoint, holometabolism is more risky—there are so many more steps to take. And yet, holometabolist insects have outcompleted hemimetabolist ones. Is there a reason for that?