The Duration and Number of the Immature Stages of Codling Moth Cydia Pomonella (L.) (Tortricidae: Lepidoptera)

The developmental rates of the immature stages of Cydia pomonella were determined at 20, 25, 30 and 35 °C, and the various instars were distinguished using head capsule measurements. There were 5 distinct instars at 20, 25 and 30 °C and possibly more at 35 °C. Rate of development increased with temperature up to 30 ° but declined at 35 °C. There was considerable variation in the developmental period due to the effects of temperature, apple variety and intrinsic differences.