Like some other wasps, hornets build large nests by chewing wood to make a type of pulp. They will build their nests in a variety of places. Typically, they are in high places like attics, treetops, eaves, hollow tree trunks, sheds, garages, and other places that are raised off the ground. Hornets will also build nests underground, sometimes in abandoned rodent burrows. They will spend the winters in tree bark, rotten logs, or crevices in the siding on buildings.