What is "instar"

Instar \In"star`\, n. a postembryonic stage of life of an arthropod, especially an insect, between two successive molts; also, the arthropod when in that stage of life.

Instar \In*star"\, v. t. To stud as with stars. [R.] ``A golden throne instarred with gems.''
--J. Barlow.

Etymology 1 n. 1 Any one of the several stages of postembryonic development which an arthropod undergoes, between molts, before it reaches sexual maturity. 2 An arthropod at a specified one of these stages of development. 3 (context by extension English) A stage in development. Etymology 2

vb. (context archaic English) To stud with stars.

n. an insect or other arthropod between molts

An instar (, from the Latin "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (ecdysis), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or changes in the number of body segments. After moulting, i.e. shedding their exoskeleton, the juvenile arthropods continue in their life cycle until they either pupate or moult again. This period of growth, instar, is fixed. Some arthropods can continue to moult after sexual maturity, but the stages between these subsequent moults are generally not called instars.

For most insect species, the term instar is used to 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 moult in insects). The number of instars an insect undergoes depends on the species and the environmental conditions. Lower temperatures and humidity often slow the rate of development.