Insect Metamorphosis

Life Cycles / Rearing

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Baby Insects


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In 1984, the Hasbro Company took the toy world by storm when it introduced the TRANSFORMERS, a group of mechanical toys designed to change from vehicles to robots and back again. These robots represented imaginary alien life forms that invaded earth and remained undetected by imitating cars and trucks. The idea of transforming from one life form to another sounds like wild science fiction to most people -- they have no idea that it happens every day right here on planet Earth. The real transformers are insects. These amazing creatures begin their lives in bodies (called larvae) that are specially designed for feeding and growing. The silkworm, for example, spends about 23 hours a day eating and increases its birth weight 86,000 times during the first 21 days of its life. When the feeding machine finishes growing, it becomes a pupa. All of the old body tissues are disassembled and rebuilt into a new life form, the adult. When the adult emerges from its pupal case, it is completely different from the larva in appearance and function. The adult is a reproductive machine, specially designed to attract a mate, produce eggs, and pass its timeless genetic heritage to the next generation of transformers.

The transformation process, known as metamorphosis, gives insects a unique survival advantage over most other living organisms. Adults may occupy a completely different habitat from the larvae; they may use a different food resource, or none at all. Metamorphosis allows them to escape from temporary habitats, like vernal ponds or deciduous leaves, before conditions become unfavorable for survival. Most insects have wings in their adult stage, and this gives them mobility to invade new habitats.

It's easy for teachers to demonstrate different types of development by rearing insects in a classroom.

Developmental Types:

Ametabolous development -- no metamorphosis
  • Development proceeds from egg to young to adult
  • Young are physically similar to adults in every way except size and sexual maturity
  • Illustrated Life Cycle
  • Classroom Examples:  silverfish, collembola
  • Hemimetabolous development -- incomplete (gradual) metamorphosis
  • Development proceeds from egg to nymph to adult
  • Nymphs show a gradual development of adult structures as they grow and mature
  • Illustrated Life Cycle
  • Classroom Examples:  crickets, grasshoppers, cockroaches, true bugs
  • Holometabolous development -- complete metamorphosis
  • Development proceeds from egg to larva to pupa to adult
  • Larvae are totally different from adults.  Larval tissues are completely
    digested and replaced by adult tissues during the pupal stage
  • Illustrated Life Cycle
  • Classroom Examples:  flies, beetles, wasps, moths, butterflies

  • Return to ENT 525 HomePage John R. Meyer
    Last Updated:   30 December 2013 Department of Entomology
    NC State University