Probability of Outbreak for Rangeland Grasshoppers (Orthoptera: Acrididae) in Montana: Application of Markovian Principles

A two-state Markov chain was used to describe the probability of rangeland grasshopper outbreaks in 56 counties in Montana. Mathematical properties of the Markov chain are discussed as they pertain to grasshopper outbreaks over a 32-yr period of historical surveys. A great deal of variation was found in grasshopper outbreak probabilities between counties. This variation will no doubt influence results of economic models that compute losses based largely upon expectations of future pest populations. The model provides information about the probability of grasshopper outbreaks that can be incorporated into economic models to improve management decisions about control strategies.