Ametabola

Ametabola is a term used in entomology to describe insects that undergo incomplete metamorphosis, meaning they hatch from the egg in a form that is almost identical to the adult, only smaller and sexually immature. This type of development is characterized by the absence of distinct nymphal or larval stages that look significantly different from the adult. Instead, ametabolous insects grow through a series of molts, with each successive molt resulting in a larger version of the insect, gradually approaching adult size and reproductive capability.

The young of ametabolous insects are often referred to as "young adults" or simply juveniles, as they possess the same basic body plan and mouthparts as the mature forms. The only significant differences are size and the presence or absence of reproductive organs. This contrasts with hemimetabolous insects, which have nymphs that resemble the adult but have undeveloped wings and reproductive organs, and holometabolous insects, which undergo a complete metamorphosis with drastically different larval, pupal, and adult stages.

Ametabola represents the most primitive form of insect development. Insects exhibiting this type of metamorphosis are typically found in the most ancient insect orders, such as the Zygentoma (silverfish and bristletails) and the Archaeognatha (jumping bristletails). These insects are often found in moist, dark environments, such as under rocks, leaf litter, or in soil. Their simple life cycle reflects their evolutionary lineage, having retained a developmental pattern that has changed little over millions of years.