Identification
metamorphosis noun - transformation in form of an insect or other arthropod during successive stages of development. Sometimes refers in particular to the change from larva to adult of an insect with
complete metamorphosis. Metamorphosis can be classified as
I=simple,
II-complete, or
III-intermediate (2).
I-Insects undergoing simple metamorphosis typically have a three-stage life cycle:
2-
nymph (resemble small adults)
3-adult (sexually mature, wings typically functional)
Simple metamorphosis may be further divided into three types:
1-ametabolous development (no metamorphosis). The adults and nymphs are wingless, and there is no visible change in form between the stages, other than in size. Ametabolous development occurs in the
Apterogytes and in other groups that undergo simple metamorphosis where the adults are wingless.
2-hemimetabolous development (incomplete metamorphosis). Immature insects (
nymphs, often called
naiads) are aquatic and breathe via gills. This pattern of development occurs in:
Odonata (dragonflies and damselflies)
3-paurometabolous development (gradual metamorphosis).
Nymphs resemble small adults and typically have external wing buds. They live in the same habitat as adults, typically taking the same food. Characteristic of many orders, for example:
Hemiptera (true bugs and allies)
Orthoptera (grasshoppers and allies)
II-Insects undergoing complete metamorphosis have a four-stage life cycle:
2-
larva, typically worm-like with several stages (
instars)
3-
pupa (resting, transformative stage)
4-
imago (adult, sexual stage, typically winged)
An insect that undergoes complete metamorphosis is called
holometabolous. The following orders have this type of development:
Neuroptera - Antlions, Lacewings and Allies
Hymenoptera - Ants, Bees, Wasps and Sawflies
Trichoptera - Caddisflies
Lepidoptera - Butterflies and Moths
Mecoptera - Scorpionflies, Hangingflies and Allies
Strepsiptera - Twisted-winged Insects
IIA-certain insects undergo
hypermetamorphosis, with an active first-instar larva (
planidium). Examples occur among beetles:
Ripiphoridae - Wedge-shaped Beetles
Meloidae - Blister Beetles
III-Several intermediate types of metamorphosis are known, that do not fit neatly into the classification of simple/complete above. These include:
Order
Thysanoptera - Thrips
Family
Aleyrodidae - Whiteflies (Order Hemiptera)
Males of superfamily
Coccoidea - Scales (Order Hemiptera)
