Hormones such as Ecdysone and bursicon play an important role during the events in moulting.
Apolysis
· Epidermal cells divide and change their shape.
· These cells separate from the inner surface of the old endocuticle and leave out the sub-cuticular space.
· This space is consisting of moulting fluid, proteinase and chitinase.
· These enzymes are inactive in this stage.
Formation of the epicuticle
· Cuticulin is deposited below the moulting fluid and above the epidermis.
· This forms the new Cuticulin layer.
· Inner protein epicuticle is deposited under the Cuticulin layer.
Deposition of new procuticle
· Deposition of procuticle occurs beneath the Cuticulin layer.
· After the deposition enzymes in the moulting fluid activate and digest the old endocuticle.
· Only a thin layer of the old endocuticle is left out.
· This layer is called as Ecdysial membrane. These lines are located in the median lines of head and thorax.
· Weak lines appear along this Ecdysial layer.
· Wax secretion occurs on to the surface of the new cuticle.
Ecdysis
· Moulting fluid and digested old endocuticle are absorbed.
· Intake of the air and muscular contractions cause the insect’s body to swell.
· This leads the old exoskeleton to split open along the weak lines.
· Insect draws itself out.
· All parts of the old cuticle are shed.
· This old cuticle is called as cast skin.
Expansion of the new procuticle
· New cuticle is soft and pale.
· At this moment new procuticle expands before it hardens.
Hardening and darkening of cuticle
· Hardening of the cuticle is known as sclerotization.
· This forms sclerites which are rigid plates of exoskeleton.
· It also darkens the cuticle. This is known as tanning.
Deposition of the new endocuticle
· New endocuticle deposits after the moulting and tanning.
