#21: Metamorphosis, Part 3 - Complete vs. Incomplete Metamorphosis

Litinsects #21: Complete vs. Incomplete Metamorphosis

Welcome to METAMORPHOSIS PART 3:

Let’s start with a recap of my last two posts... Within winged insects (or PTERYGOTES), there are two different developmental strategies:

HOLOMETABOLOUS insects undergo complete metamorphosis with 4 stages: egg, larva, pupa, and adult. All stages look completely different from one another

HEMIMETABOLOUS insects undergo incomplete metamorphosis with 3 stages: eggs, nymph, and adult. The nymphal stages physically resemble the adults

Nymphs of hemimetabolous insects typically share the same food and habitat as adults and exhibit similar behaviors whereas holometabolous insects usually look different, display different behaviors, and occupy different habitats in each life stage. The takeaway here is that holometabolous insects are very good at compartmentalizing certain tasks into different life stages, in order to reduce or eliminate competition among life stages!

Think about it, a caterpillar looks differently, behaves differently, and eats different foods from a grown butterfly... the benefit of this is that parents don’t need to compete with their own offspring for food. In general terms, a larva’s job is basically to eat and grow, an adult’s job is basically to reproduce, and each life phase comes equipped with different structures or behaviors to best complete its respective tasks.

Immature insects don’t have to worry about mating because they have no reproductive organs, but eat a lot to gain the energy needed for metamorphosis so they are usually equipped with mouthparts that are practical for their food source. Conversely, reproduction is the most important job an adult individual has; breeding is SO important that some adult insects rarely feed or don’t even have mouthparts as an adult and some literally die right after mating!

I am not saying that hemi- or ametabolous insects are less equipped or worse off than holometabolous ones. But there is no denying the advantages to the holometabolous life style and it is no surprise, when you look at the number of species that undergo complete metamorphosis, that this strategy is just SO successful!

This picture is of a tiny fly and its pupal casing.

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