01.05 Metamorphosis, Dispersal, and Reproductive Capabilities

AMETABOLOUS / AMETABOLIC DEVELOPMENT

development without any changes in body form (no metamorphosis), in which the only difference between life stages is size and a lack of functional reproductive structures in immatures.

APTERYGOTES

insects that have never had wings throughout evolutionary history. notable examples include the silverfish and bristletails.

INCOMPLETE METAMORPHOSIS

a type of development found in some insects in which there are gradual changes in body form. immatures are similar to adults except for a lack of wings and functional reproductive organs.

HEMIMETABOLOUS / HEMIMETABOLIC DEVELOPMENT

development with gradual changes in body form, in which immatures, called nymphs, are morphologically and ecologically similar to adults but do not have fully developed wings. all these insects undergo incomplete metamorphosis.

Nymphs

an immature stage of an insect that undergoes incomplete metamorphosis.

Naiads

sometimes also called nymphs, an aquatic immature stage of an insect that undergoes incomplete metamorphosis.

EXOPTERYGOTES

insects with wings that develop as wing buds external to the body wall. all these insects undergo incomplete metamorphosis.

COMPLETE METAMORPHOSIS

a type of development found in derived insect taxa in which there are drastic changes in body form. immatures are very different from adults both morphologically and often ecologically is characterized by four distinct stages: 1) Egg, 2) Larva, 3) Pupa, and 4) Adult.

HOLOMETABOLOUS / HOLOMETABOLIC DEVELOPMENT

development with drastic changes in body form in which immatures, called larvae, are morphologically and ecologically distinct from adults and lack wings and functional reproductive structures.

PUPA

an immature life stage of holometabolous insects between the larva and the adult. this stage does not feed, and is typically immobile. in butterflies, this stage is often called a chrysalis, a few hemimetabolous insects also have this stage, such as thrips (Thysanoptera) and whiteflies (Aleyrodidae).

COCOON

a covering made of silk or other material that encases a developing pupa.

PUPARIUM

a protective covering around a pupa formed by the hardened cuticle of the final larval instar. occurs in the Strepsiptera, some Diptera, and whiteflies (Aleyrodidae).

ECLOSION

the emergence of an adult insect from its pupal case, or the emergence of a larval insect from its egg.

LARVA pl. LARVAE

an immature insect that has emerged from the egg stage. usually restricted to insects with complete metamorphosis, but sometimes used for any immature insect (as well as immature stages of other animals).

IMAGINAL DISCS

a group of undifferentiated cells in larval insect destined to become external structures of the adult stage. wings in endopterygote insects are formed from these.

ENDOPTERYGOTES

insects with wings that develop as imaginal discs within the body wall. all these insects undergo complete metamorphosis.

HOLOMETABOLA

insect group that undergoes holometabolous development. synonymous with Endopterygota.

Hormone

a chemical substance that travels through an organism's fluids to regulate activities of target cells or tissues.

JUVENILE HORMONE (JH)

a hormone found in insects that regulates multiple aspegts of their physiology, such as development, metamorphosis, and reproduction, and is secreted by the corpora allata into the hemolymph.

DIAPAUSE

an arrest in activity and development during unfavorable environmental conditions. unlike hibernation, diapause can occur in any season.

Corpora Allata into the hemolymph

Where is JH secreted from, and where is it secreted into?