Moulting and reproduction in the adult firebrat, Thermobia domestica (Packard) (Thysanura, Lepismatidae)—I. The moulting cycle and its control

Under optimal conditions, adult firebrats moult about every 9 days (English strain) or 13 days (American strain), irrespective of age, sex, or reproductive activity. The epidermis is activated on the 4th or 5th day of the 9-day stadium and the deposition of the cuticle follows 2 days later. There is a critical period for the secretion of a brain hormone on the 5th or 6th day of a 13-day stadium, equivalent to the 3rd or 4th day of the 9-day stadium; maximal activity in the ventral gland coincides with or follows shortly after this, also coinciding with the activation of the epidermis. Thus the control of moulting in Thermobia closely resembles that in the pterygotes.