The main signs of a ground-based hornet's nest are tiny burrows in soil, which causes a horseshoe-shaped pile of dirt at the top. The burrows are usually an inch and a half in diameter, 10 inches deep and 18 inches long beneath the ground.
The most obvious way to determine if a hole is a hornet nest is a sighting of a hornet flying in and out of the hole. Ground hornets are very large with black bodies and yellow tail ends. They are the largest type of digging wasps in the United States. They do not form colonies in hives or nests like bees or other social varieties of stinging insects. Each female ground hornet digs its own burrow to use as a nest and then lays its eggs deep within. The male ground hornet defends the nest by buzzing loudly and attacking anyone that poses a threat to the nest. Although females have stingers, they only use them to kill cicadas.
Lawns can be destroyed when large numbers of ground hornets burrow into the soil. Although most burrows are positioned in sunny locations, you can find a ground hornet's nest anywhere, including borders of driveways, potted plants on patios, flower beds and golf courses. Most of the time, hornets dig their burrows in dry or sandy unfertilized soil.