The hypodermis is composed of parts of two different kinds, viz.
Exoskeleton The outer cellular layer (ectoderm or " hypodermis ") of insects as of other Arthropods, secretes a chitinous cuticle which has to be periodically shed and renewed during the growth of the animal.
This cellular layer is called the hypodermis; it is protected externally by a cuticle, a layer of matter it itself excretes, or in the excretion of which it plays, at any rate, an important part.
The cuticle contrasts strongly in its nature with the hypodermis it protects.
By histolysis certain parts of the hypodermis are destroyed, while other portions of it develop into the new structures.