Imagine being so teeny tiny that you are an endoparasite on *leafhoppers* Leafhoppers are already in the "so small they go unnoticed" category, and you're just a little pest on a minuscule thing.
Of course the group that's most likely to choose this life? The wasps Wasps are some of the smallest insects. There are "fairy flies" that are parasites of the eggs of certain insects.
They are so small that air is "thick" to them and their wings have feathered edges are are oar shaped.
Some fairly flies are so tiny that their neurons are cells without nuclei. They got rid of them to save space. They can still think though... presumably the tiniest little thoughts.
Photo by Alexey Polilov, 2012
They lay their eggs inside of the eggs of 1-2mm long crop pests.
And... read the article to see what the males are like... they are even smaller somehow, but it's ... disturbing.