The population growth of Elasmopalpus lignosellus (Zeller), the lesser cornstalk borer (Insecta: Lepidoptera: Pyralidae), was determined in conventionally tilled Florunner peanut fields in endemic (1983–1985) and outbreak (1986) population configurations. The density of E. lignosellus eggs, larvae, and pupae was estimated by weekly soil flotation and by soil sieving. Adult density and abundance was estimated with pheromone traps, emergence cages, and flush samples.

In the endemic years, low levels of eggs, larvae, pupae, and adults occurred throughout the growing season. Adult populations exhibited 1–2 weak peaks per growing season. The outbreak year was characterized by an exponential increase in E. lignosellus eggs, larvae, pupae, and adults.

A regression relationship was developed from the 1983–1986 data that relates the weekly mean number of E. lignosellus larvae per meter determined by soil sieving to the total rainfall (cm) and the number of hot (≥35 C daily maximum temperature) days in the previous 30 days. This is a predictive tool that can be used to time sampling to predict possible larval population increases before extensive damage occurs.