Plant Phenology as a Guide in Timing Grasshopper Control Efforts on Montana Rangeland

Abstract

The flowering of 28 forb species at two locations was correlated with grasshopper development in 1977 and 1978. Indicator plants whose flowering phenology was associated with grasshopper hatching included: Zygadenus elegans, Allium textile, Delphinium bicolor, Oxytropis sericea, Erysimum asperum, Leucocrinum montanum, and Astragalus gilviflorus. The ideal time for controlling grasshoppers (when most of the population is in the 3rd instar) was associated with the flowering phenology of the following indicator plants: Yucca glauca, Helinathus petiolaris, Opuntia polyacantha, Sphaeralcea coccinea, Antennaria dimorpha, Tragopogon dubius, Cryptanthe celosioides, Allium textile, Delphinum bicolor, Zygadenus elegans, and Erysimum asperum.