TEMPERATURE AND CIRCADIAN CONTROL OF CUTICLE GROWTH IN BUG ONCOPELTUS FASCIATUS

The endocuticle of adult Oncopeltus fasciatus grows by daily increments until it reaches maximum thickness when growth ceases. Each day a nocturnal lamellate and a diurnal non-lamellate layer are deposited. These are under the control of a circadian rhythm initiated by a light-dark cycle impinging upon the pharate adult. Cuticular growth rate is a direct linear function of temperature, and there is therefore an inverse relationship between temperature and number of paired rings in fully mature adults. At 19°C the mean number of paired rings is 10·4 whereas at 31°C it is 5·3. Thus in order to age insects by counting paired rings, the temperature at which growth took place must be known. © 1969.