The western yellow jacket, or wasp, is the species of yellow jacket that occurs in California and most states west of the Great Plains. Western yellow jackets, unlike other yellow jackets, feed on dead insects. They also feed on carrion and other garbage, and can become a nuisance at outdoor picnics.
Western yellow jackets build their nests in the ground or under structures, such as porches. Their nests are made of paper or cellulose that has been chewed by the wasps to form cells for the larvae. If the nest is disturbed, western yellow jackets can deliver a painful sting. And unlike bees, they can sting multiple times.
A professional pest control expert should remove a western yellow jacket nest. To help control western yellow jackets, make sure all garbage can lids are tight and any outdoor pet food is covered. If you have fruit trees, be sure to remove all rotting fruit from the ground.