Insect Stages, Growth
Arenda, Clarise D.
Valdecantos, Anjeline R.
DEFINITION OF TERMS:
• Metamorphosis - the transformation of a larva,
nymph, or naiad into an adult insect.
• Hemimetabolous Metamorphosis – incomplete
• Holometabolous Metamorposis - complete
• Ametabolous Metamorposis- no change in the
body form of insect.
• Eclosion- is used to denote the process of
hatching or exciting from the egg.
• Instar - a developmental stage of arthropods,
such as insects, between each molt (ecdysis),
until sexual maturity is reached.
• The vast majority of insects lay eggs, and the
development of the embryo progresses
outside the mother’s body.
• Most species undergo metamorphosis. Nearly
all insects display either hemimetabolous
metamorposis or holometabolous
• Few change so little, except in size, that they
said to have ametabolous metamorposis.
HEMIMETABOLOUS insects are usually
distinguished by immature stages, called nymph,
that resemble adults, the main changes being an
increase in size and the development of sexual
organs and wings.
Examples: Dragonflies, damselflies, mayflies and
HOLOMETABOLOUS insects consists of four distinct stages:
1. From the egg hatches a larva.
2. Larvae molt several times to accommodate growth.
3. At the end of the larval stage, a final molt may occur with
the pupa emerging.
• A great transformation is occurring. The developing wings
can often be seen, as can the compound eyes, antennae,
mouthparts and legs.
4. At the eclosion, the adult emerges, within hours the wings
unfurl, becoming stronger as the veins dry and stiffen, and the
exoskeleton dries, hardens and gains pigments.
• It denote the developmental stage of
the larval or nymphal forms
of holometabolous (complete metamorphism)
or hemimetabolous (incomplete
metamorphism) insects, but the term can be
used to describe any developmental stage
including pupa or imago (the adult, which
does not molt in insects).
AMETABOLOUS insects emerge from eggs into
immatures of virtually the same shape as the
adults. They're considered ametabolous because
the insects simply get bigger and do not undergo
any distinct rearrangements of body structures
between the immature and adult stages.
• Eggs are laid on plants by the adult female
butterfly. These plants will then become the
food for the hatching caterpillars.
• Eggs can be laid from spring, summer or fall.
This depends on the species of butterfly.
Females lay a lot of eggs at once so that at
least some of them survive.
LARVAL STAGE OF INSECTS
• Primary functions are to eat and grow.
• Wormlike in appearance
• Posses a series of simple eyes, chewing-
sucking mouthparts, a pair of very short
antennae, and sometimes three pairs of true
• Developing wings are hidden in the cuticle.
• When the caterpillar is full grown and stops
eating, it becomes a pupa. The pupa of
butterflies is also called a chrysalis.
• Depending on the species, the pupa may
suspended under a branch, hidden in leaves or
buried underground. The pupa of many moths
is protected inside a cocoon of silk.
• This stage can last from a few weeks, a month
or even longer. Some species have a pupal
stage that lasts for two years.
• Special cells that were present in the larva are
now growing rapidly. They will become the
legs, wings, eyes and other parts of the adult
butterfly. Many of the original larva cells will
provide energy for these growing adult cells.
ADULT STAGE OF INSECTS
• The adult stage - also called the imago - is
often capable of moving quite long distances
in order to colonize new areas, and insects
may perform special routines in order to find
or attract a mate.
• After mating and (internal) fertilization, eggs
are laid, usually near to a potential source of