#20: Metamorphosis, Part 2

#20: Metamorphosis, Part 2 - Hemimetabola

Litinsects #20: Hemimetabola

Welcome to METAMORPHOSIS PART 2:

Yesterday I discussed complete metamorphosis, where an individual’s appearance changes pretty drastically through its life stages. But some insects undergo a different kind of transformation: INCOMPLETE METAMORPHOSIS. These insects are HEMIMETABOLOUS (hemi = half/part, metabola = change) because they go through gradual changes to their body layout. This includes 3 life stages: egg, nymph, and adult.

1) As usual it starts with an EGG

2) A NYMPH emerges, which generally resembles the adult form of the insect but WITHOUT WINGS. Nymphs molt several times, growing in the process, but never enter a pupal stage. These nymphal stages are called INSTARS

3) The ADULT insect emerges after the final molt, with WINGS and REPRODUCTIVE ORGANS.
Nymphs may differ from adults in coloration or body proportions but hemimetabolous insects usually have similar diets in all life stages.

This type of metamorphosis is found in true bugs, grasshoppers, dragonflies, termites, mantises, cockroaches, cicadas, and more...

These photos are of a wheel bug adult and nymph. Notice how they look physically very similar other than that the nymph has no wings and a different coloration.

The most simple (and probably least well known) type of metamorphosis is AMETABOLISM (a = without, metabola = change). Ametabolous insects hatch as tiny versions of the adult and simply increase in size with each molt until sexual maturity is reached. This transformation occurs only in the most primitive WINGLESS groups, silverfish and bristletails.

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