"Thrips are tiny insects, typically just a millimetre in length. Some are barely half that size. If that’s how big the adults are, imagine how small a thrips’ egg must be. Now, consider that there are insects that lay their eggs inside the egg of a thrips."
How tiny wasps cope with being smaller than amoebas
Includes mention of the lengths other tiny insects go to. Such as doing away with unnecessary organs like hearts.