What do Silverfish and Firebrats have in common regarding their developmental stages?

Silverfish and Firebrats are both considered primitive insects that belong to the order Thysanura. One key aspect they share in their developmental stages is that they do not undergo any metamorphosis, which includes both complete and incomplete metamorphosis. Instead, they develop through a simpler process known as ametabolism, where they hatch from eggs and gradually grow into adults, without distinct larval or pupal stages.

This means that unlike insects that undergo significant changes in body structure during their life cycle—such as butterflies that have larval (caterpillar) and pupal (chrysalis) stages—Silverfish and Firebrats maintain a more consistent form as they mature. They simply become larger versions of their nymphs. This lack of metamorphosis is a defining trait of these insects, emphasizing their primitive evolutionary adaptations.