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Grasshopper Survey
The 2013 Oregon grasshopper survey season showed that the grasshopper population continues its decline from a high in 2011.  Surveying began on 13 May and ended on 22 August.  Approximately 0.87 million acres across 15 counties in eastern Oregon were estimated to be economically infested.  The 2013 report is now available for viewing and downloading.

 
Report Summary (pdf, 339 KB)
Full report (pdf, 960 KB)
Maps
 
Overall climatic conditions were again dry and warm this season.  APHIS/ODA undertook one cost share treatment program in 2013.  Dimilin, an insect growth regulator, was used to treat 312 acres of federal land in Klamath County.  A 50% skip swath IPM technology was used, resulting in 624 acres protected.  This treatment was done in conjunction with private treatments on adjacent private rangeland, ~1,600 acres.  In addition to this treatment ODA/APHIS provided grasshopper population information and treatment recommendations to interested landowners in areas experiencing high populations.

Last year (2012) it was not clear if grasshopper population densities that were slightly lower than 2011 signaled the start of an outbreak decline or were an artifact of having to scale back our survey effort.  While the survey resources are still down it does appear that the densities found this year indicate an end to the widespread outbreak.  When this year's areas of economic density are adjusted for sampling effort the population decline from 2012 to 2013 is much greater than that between 2011 and 2012.

This does not mean the pattern of decline is evident across all regions, nor that significant grasshopper densities are not a problem at the local level.  Land owners in southern Klamath and Lake Counties, and northern Harney County, where densities are still quite high and may even be on the increase, should pay close attention during the hatching period in spring of 2014.  Areas in central Baker and Union counties also experienced a slight of increase during 2013 and warrant close observation.


Site Specific Environmental Assessments for 2014 and the previous three years are available on ODA's website.
 
For further information or resources please contact Paul Blom at pblom@oda.state.or.us