The statistical analysis of insect phenology.

We introduce two simple methods for the statistical comparison of the temporal pattern of life-cycle events between two populations. The methods are based on a translation of stage-frequency data into individual 'times in stage'. For example, if the stage-k individuals in a set of samples consist of three individuals counted at time t(1) and two counted at time t(2), the observed times in stage k would be (t(1), t(1), t(1), t(2), t(2)). Times in stage then can be compared between two populations by performing stage-specific t-tests or by testing for equality of regression lines of time versus stage between the two populations. Simulations show that our methods perform at close to the nominal level, have good power against a range of alternatives, and have much better operating characteristics than a widely-used phenology model from the literature.