I received the following e-mail that, I think, describes the European hornet very nicely.  This is the only true hornet found in the United States. It bears black on yellowish-orange markings on its abdomen, very similar to the yellowjackets that we are all familiar with. Sometimes it is called a 'giant hornet' because it is so much larger than our typical yellow jackets (up to 1.5 inches in length).  It was introduced into New York in about 1840 and now has spread throughout most of the Eastern states. It rarely builds nests that are free hanging but usually covers the entrance to a cavity or hole with its nest made of coarse, tan colored, paper-like material. Like yellowjackets, only the queen passes the winter and nests are NOT reused in a subsequent year.   Mature colonies contain from 300 – 500 workers (occasionally more) and prey mostly on large insects (grasshoppers, flies, bees and yellowjackets).  E. hornets are very beneficial and seldom really require controls.  Only if their nest is directly in the way of people should they ever be destroyed.  As the e-mail suggests, E. hornets also are active at night - unlike other stinging wasps.  This complicates treatment timing for these wasps slightly, otherwise, they may be treated for in the same manner as yellowjackets.