Photo: Diane Edwardson, April 5, 2012. California Harvester Ants are NOT Red Imported Fire Ants. (Click on photo to enlarge.)
April seems to bring the California Harvester Ants out from under the Red Car Property near Adelbert. California Harvester Ants are a native species and should not be confused with aggressive Red Imported Fire Ants. Harvester Ants are NOT aggressive.
I've read Environmental Impact Reports citing the presence of Harvester Ants as an "indicator species." In other words, their presence is a sign of good biodiversity of the land.