Yellow jackets become more aggressive this time of the year. The population of nests is highest during the fall, increasing demand for food. Because colony members protect the food source in the nest, anything intruding into the nest area will be stung.
Yellow jackets often are mistaken for bees, but they are actually wasps with distinct yellow and black markings. Like other wasps, they make a paper nest, usually underground in stump holes, stumps or under shrubs. Occasionally yellow jackets will nest in attics, old cars or in walls of buildings.