Instar

Epiphyas postvittana 5^th instar larva

An instar is a developmental stage of arthropods, such as insects, between each molt, up 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 or changes in the number of body segments. Some arthropods can continue to molt after sexual maturity, but these subsequent molts are generally not referred to as instars.

For most insect species the term "instar" is used to denote the developmental stage of the larval or nymphal forms of holometabolous or hemimetabolous insects, however the term can be used to describe any developmental stage including pupa or imago (the adult, which does not molt in insects). The number of instars an insect completes depends on the species and the environmental conditions with cooler temperatures and lower humidity often slowing developmental rates. Nonetheless, there seem to be some limits, and it is rare for an insect to pass through any fewer than 4 total larval instars before reaching maturity ^{[[Citing sources citation needed]]}.

From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.