Semiquantitative sweep surveys of aquatic habitats were made before treatment, 2 weeks after treatment, and 4 months after treatment (after leaf fall) at Grouse Creek. Pitfall traps at four treated and four untreated sites were used to collect ground-dwelling terrestrial arthropods. Geological Survey scientists sampled areas in Ibapah and Vernon that had been treated with diflubenzuron in 2004, along with adjacent untreated areas. Terrestrial and aquatic arthropod communities were sampled before and after application of diflubenzuron in the Grouse Creek area of northwestern Utah in May and June of 2005. Diflubenzuron was applied (aerial reduced agent-area treatment) in May 2005. High mortality of Mormon cricket eggs in the wet, cool spring of 2005 restricted the need to control Mormon crickets to Grouse Creek.

Three areas were sampled: Grouse Creek, Ibapah, and Vernon. This study was instigated in anticipation of the need for extensive control of Orthoptera outbreaks in Utah’s west desert during 2005, and it was designed to sample terrestrial and aquatic arthropod communities in both treated and untreated zones. Some research has been done in the Great Plains on the impact of diflubenzuron on nontarget arthropods in the context of grasshopper-control programs, but no work has been done in the Great Basin in Mormon cricket-control areas. Consequently, application of this pesticide has the potential to significantly reduce not only target populations but all terrestrial and aquatic arthropods within treatment zones. Diflubenzuron is not taxon specific-it affects all arthropods that ingest it, except adult insects, which do not molt. All arthropods, including insects, mites, and crustaceans, use chitin to build their exoskeletons and will die if they are unable to produce it during the next molt. A relatively new insecticide for control of Orthoptera is diflubenzuron, which acts to inhibit chitin production, ultimately causing death during the molt following ingestion of the insecticide. A variety of insecticides have been applied to control population outbreaks, with recent efforts directed at minimizing impacts to nontarget fauna in treated ecosystems. Grasshopper and Mormon cricket (Orthoptera) populations periodically build to extremely high numbers and can cause significant economic damage in rangelands and agricultural fields of the Great Plains and Intermountain West.