Calculations of Temperature‐driven Development by Heliothis Spp. (Lepidoptera: Noctuidae) in the Namoi Valley, New South Wales

Previously published information on effects of constant temperatures on development by Heliothis spp. was used with long‐term temperature records for the Namoi Valley to calculate the durations of different developmental stages starting on each day of the year. Calculations of the number of generations per year and the period in which pupal diapause is necessary were consistent with light‐trap data and other observations published elsewhere. A figure showing times taken from oviposition to egg hatch and to one third‐grown larva in different months indicates numbers of days available after oviposition in which insecticides must be applied for maximum effect.