Adult hornets and their relatives feed themselves on nectar and sugar-rich plant foods and are thus often seen on the sap of oak trees, rotting sweet fruits, honey and any sugar-containing foodstuffs. Hornets tend to gnaw a hole into fruit to be totally immersed in its meat. The adults prey on various insects as well, which they kill with stings and jaws. Due to their size and the power of venom, hornets are able to kill large insects such as honeybees, grasshoppers, locusts, and mantises without difficulty or much effort. The victim is chewed and then fed to the larvae developing in the nest, rather than consumed by the adult hornets.

• Hornets are often confused with other wasps, specifically the yellow jackets, which are members of the same subfamily.
• Yellow jackets are generally smaller than hornets and are bright yellow and black, whereas hornets may often be black and white.
• Given that some of their prey are considered pests, hornets may be considered beneficial under some circumstances.