Oregon Grasshopper and Mormon Cricket Survey
Summary for 2012
The 2012 Oregon grasshopper survey season, conducted by the Oregon Department of Agriculture (ODA) in cooperation with the Oregon United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) Plant Protection and Quarantine (PPQ) office, revealed that the grasshopper population is still a significant concern in many areas for the state, though perhaps declining from the infestation levels of 2011. Surveying began on 4 June and ended on 4 September. Nymphal survey takes place early in the season and is used to locate potential outbreak areas. Adult survey (10 July - 4 September) is used by APHIS to make predictions for 2013 and estimated economic levels of 8 or more grasshoppers per square yard.
In 2012, a total of 1,135 sites were visited. Though we heard report of some Mormon Cricket activity this year it was limited and none were found in our survey. Of the total stops 387 were during the period for nymphal grasshopper survey and 748 during the adult period. Approximately 1.18 million acres across 17 counties in eastern Oregon were estimated to be economically infested. Sixteen of these counties had greater than 10,000 economically infested acres.
Survey Statistics from 2005 through 2012. Economic infestation ³
8 grasshoppers / yd2.
Number Acres of Samples Mean Number
Counties Econ. w/Econ GH
Year Infested Infest. Total Nymph Adult Treatment Density yd2* Surveyors
2012 17 1,178,872 1,135 387 748 34 526 34 2.5
2011 18 2,888,455 3,139 1880 914 345 1093 20 6
2010 12 1,910,222 1,905 795 750 360 488 21 6
2009 11 151,974 998 491 507 108 18 4
2008 12 1,129,820 2,722 1116 1606 360 29 6
2007 13 798,358 1,585 706 870 298 18 6
2006 14 97,399 1,368 750 618 100 16 6
2005 9 64,751 859 306 423 115 15 5
*Mean of economically infested
Climatic conditions and range fires affected the survey this year. Unlike the previous two summers cool and wet weather did not persist well into June during 2012. In fact drought conditions developed over much of the southeastern OR grasshopper range. Ultimately these dry conditions coupled with fuel load from 2011 produced some major range fires locally impacting this year’s densities and likely those in the following years.
While it appears the economically infested acreage in OR is declining, it is dangerous to conclude the outbreak of the last few years is waning. Budget limitations forced us to reduce our sampling efforts by ~2/3 during 2012. To do that we had to reduce scouting personnel to ~2.5 / week and the total number of sites surveyed to ~1/3 of 2011. Thus we estimate survey for only ~3.5 million acres in 2012 compared with 7.4 million in 2011.
comparison of grasshopper (GH) infestation densities (/ yd2)
adjusted for effort.
Percent of Total Surveyed Acres Estimated
Year Economic non-Econ No
GH Total Economic non-Econ No
2012 33.7 46.8 19.6 3,503,235 1,178,872 1,639,468 684,895
2011 38.9 43.4 17.7 7,422,908 2,888,455 3,220,585 1,313,868
Map of the 2012 estimated areas of surveyed showing three levels of infestation.
We participated in one suppression program this season at the Klamath Marsh, Klamath County. June scouting on the Klamath Marsh National Wildlife Refuge (KMNWR) and surrounding private holdings indicated the marsh would again experience the high population densities it had in the previous two seasons. A collaborative effort was undertaken between the Fish and Wildlife Service (FWS), APHIS and the private landowners to attempt a suppression of the population. Due to logistics and various complications it took over three weeks to actually begin treatments. During this time the grasshopper populations increased in age, density and geographic spread. Landowners applied Dimilin, an insect growth regulator, too late in the grasshopper development and APHIS was only able to treat ~590 ac of KMNWR land using Carbaryl bait. In the end 7,497 acres were treated by private landowners on their lands and ~ 590 on the Refuge were treated by APHIS.
Though there may have been declines in some local grasshopper populations, economic densities were still found widely across eastern Oregon during 2012. Thus, we recommend landowners and managers be prepared for the outbreak in Oregon to continue in 2013. We cannot accurately predict where grasshopper outbreaks will occur because they depend greatly on many factors at the time of hatch and early development, variables that cannot be accurately forecast. However, we consider it likely that the patterns of economic densities will continue in 2013. If conditions cause the crash of this outbreak we can consider ourselves fortunate, however, planning for a continuation of the patterns of the past few years is the only prudent course of action.
We encourage landowners in areas with high or building populations in 2012 to be especially proactive in early 2013 if they are concerned about grasshopper impacts to crops and rangeland. Control is most effective on young grasshoppers. Contact us or your local Extension Office for advice, assistance, or to report grasshopper populations. Full Report
Paul Blom, Oregon Department of Agriculture, Salem, OR, 503-508-1253, firstname.lastname@example.org
Gary Brown, USDA-APHIS Portland, OR, 503-326-2814 (ext. 239), Gary.W.Brown@aphis.usda.gov