Word Finder - instar

definition

Any one of the several stages of postembryonic development which an arthropod undergoes, between molts, before it reaches sexual maturity.

definition

An arthropod at a specified one of these stages of development.

definition

(by extension) A stage in development.

Young resembling parents, but penultimate instar passive and enclosed in a filmy pellicle.

The new instar - or temporary form - is often very different from the old one, and this is the essential fact of metamorphosis.

But examples are not wanting of a more or less complete resting habit during the latest nymphal instar.

Young animals always unlike parents, the wing-rudiments developing beneath the larval cuticle and only appearing in a penultimate pupal instar, which takes no food and is usually passive.

Pupa incompletely obtect or free, and enclosed in the hardened cuticle of the last larval instar (puparium).

The change from an exopterygote to an endopterygote development could, therefore, be brought about by the gradual postponement to a later and later instar of the appearance of the wing-rudiments outside the body, and their correlated growth inwards as imaginal disks.

As the life-conditions and feedinghabits of the larva and imago become constantly more divergent, the appearance of the wing-rudiments would be postponed to the pre-imaginal instar, and that instar would become predominantly passive.

In at least one genus the unjointed pincers of the forceps are preceded, in the youngest instar by jointed cerci.

There is an easy exit for the tiny first instar caterpillar to escape from the confines of its egg.

Once in the final instar, I was able to use the caterpillars guide by Jim Porter to identify them.

When they hatch the first instar of the larval stage is very small and makes tiny holes in the leaf.

The upper image is of an early instar - probably stage 2. The search for food causes the family group to disperse.

The 5th larval instar, is followed by the winged imago stage which are 3mm long and brown-black in color.

The five young animals molted to second instar within a few weeks.

Its condition thus recalls the pupal instar of the higher (Endopterygote) Hexapoda; and the Thysanoptera, though few in number, are seen to be of great interest to the student, exhibiting at once a transition between the biting and the suctorial mouth, and the passage from " incomplete " to " complete " metamorphosis.

Some pupae are thus more active than some nymphs; the essential character of a pupa is not therefore its passivity, but that it is the instar in which the wings first become evident externally.

Further, although the wing-rudiments appear externally in an early instar of an exopterygotous insect, the earliest instars are wingless and wing-rudiments have been previously developing beneath the cuticle, growing however outwards, not inwards as in the larva of an endopterygote.

The final instar is normally collected (slide 14) before the caterpillars fall to the ground and pupate just below the soil surface.

Among a few of the beetles or Coleoptera, and also in the neuropterous genus Mantispa, are found life-histories in which the earliest instar is campodeiform and the succeeding larval stages eruciform.

In the metabolic Hexapoda the resting pupal instar shows externally the wings and other characteristic imaginal organs which have been gradually elaborated beneath the larval cuticle.

Penultimate instar a flying sub-imago.