Metamorphosis
Insect development takes several different forms. These can be grouped into two broad categories - complete and incomplete metamorphosis.
This metamorphosis, or change in structure with age, is partly necessitated by the insect's external skeleton. Because the insect is covered in a hard cuticle it cannot grow without shedding its skin.
Insects are classified according to their metamorphosis. The simplest insects, the Apterygota have a very simple development. Each stage is merely a larger version of the one before.
All other insects are placed in the Pterygota. This group is subdivided into Exopterygota, which undergo incomplete metamorphosis, and the Endopterygota, which undergo complete metamorphosis.
Incomplete Metamorphosis
The egg hatches into a small insect known as a larva or nymph. This is very similar to the adult, but lacks wings, and the sexual organs are under-developed. With each moult, the insect not only gets bigger but is slightly more developed. Each stage after a moult is known as an instar.
Thus the larva that hatches from the egg is the first instar. After it has moulted, it becomes the second instar, etc.
The life cycle of the Emerald Damselfly, Lestes sponsa
This picture is taken from the forthcoming Peregrine Productions A5 identification plate DRG2 'Damselflies 1'
Complete Metamorphosis
The life cycle of the Green Hairstreak Butterfly, Callophrys rubi
This picture is taken from the Peregrine Productions A5 identification plate BTF2 'Hairstreaks'
For details of this and other plates, see our catalogue
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