Questions such as when to plant, whether the crop is developing on time, and when to initiate pest control actions are particularly difficult to answer, because the timing is not always the same each year. Growth and development of insects and plants can vary as much as two to three weeks from the “normal” time, depending on whether temperatures are above or below the average. In this article we compare different techniques for predicting temperature-related insect population and crop development.

The authors thank Andrew P. Gutierrez, Robert M. Nowierski, Richard E. Rice, and Charles G. Summers for providing development threshold and rate estimates and for helpful suggestions, and Peggy Kaplan for her typing and editorial assistance.