European Grapevine Moth Mapping (EGVM) Application
The Napa County GIS Department has created a mapping application to show the locations of European Grapevine Moth (Lobesia botrana) finds within Napa County. This information is not parcel or field specific to maintain the privacy of landowners and farmers. If you need detailed information, please contact the Napa County Agricultural Commissioner's Office at (707) 253-4357.
Visit the mapping application: http://gis.napa.ca.gov/gcmaps/?Viewer=EGVM
Instructions:
This mapping application functions best when viewed using Internet Explorer.
NEW information now available. We have added a layer that displays a 500-meter buffer around all 2010 EGVM finds. To view this layer simply zoom-in to your desired area until you're able to select the "EGVM 500m Buffer" in the legend. You must zoom-in considerably close for this option to be available. This information will be helpful in determining treatment areas in Napa County. As moths are found in 2011, this map will be updated to reflect positive 1/25 square mile subgrids.
To use this mapping application: Click anywhere on the map to zoom-in to desired area. As you zoom in the colored dots will change to highlighted squares. Each colored square represents at least one European Grapevine Moth find within that 1/25th of a square mile. The colored square will be labeled with a five or six-digit number in the following format: 0000-0 or 0000-00. The square mile grid will also be visible and labeled with a four-digit number.
Click on the "Show Legend" button on the bottom left of the screen to see which flight generation the EGVM find occured in (based on the color of the square). Moths found during ther first flight is displayed in red. Use the tools on the toolbar above the map to zoom in, zoom out, pan, etc.
To see the actual date the EGVM was discovered within that 1/25th of a square mile, select the "identify" tool on the toolbar then click on a colored square; a new window will open. Select the second tab called "Trap Cells" and double-click on the trap number listed under the third column, "SubGrid ID." The date is listed in the "SampleDate" row.
The purpose of this mapping application is not to count specific EGVM finds, but to determine the extent of the spread. If you need to know specific population numbers, see the newsletters on the UC Cooperative Extension EGM Monitoring and Management Page. The EGVM traps are serviced on a biweekly schedule so the data captured in this application is on a two-week delay.