Molting and metamorphosis

To date, interest in the ecdysteroids has focused primarily on their role in insect molting and metamorphosis and it is perhaps somewhat unfortunate that bioassays for ecdysteroid activity have been restricted almost exclusively to evaluating their effect on the molting process. It now appears probable that molting is just one of several important regulatory functions (e.g., embryogenesis, reproduction) performed by the ecdysteroids and that we are only just beginning to scratch the surface of an insect steroid system that is equally as complex as that in vertebrate species. 

The molting and other hormonal activities of the ecdysteroids are, of course, modulated by the titer of the insect juvenile hormone and the two materials typically function in close concert with one another in dictating insect molting and metamorphosis as well as in reproductive maturation (21). 

Eedysone was the first insect hormone to be obtained in pure crystalline form. It has the action of the molting and metamorphosis hormone and has also been called, by Scharrer, the growth and differentiation hormone . 

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