Yellow jackets are fierce and the insect most likely to sting. Yellow jackets are sleek, yellow and black insects that fly extremely well. Most nest in the ground, but a wall-void nesting yellow jacket species, Vespula germanica, which was introduced from Europe, has increased in numbers in recent years and is now a serious problem at parks and backyards where it scavenges for food. Yellow jacket workers present a major stinging pest problem because their stings cause pain, swelling and discomfort, and they tend to nest around humans. These scavengers are attracted to trash areas, garbage cans, and areas where sugary fluids are.
Hornets are aerial nesters and, like their relative the yellow jacket, make nests of paper.
They are longer than yellow jackets and either yellow and black. In Delaware, the most common hornet is white and black in color. The nests, which can reach basketball size by summer's end, are located in trees, shrubs, and sometimes on buildings. Since the nests grow in size with the season, they often are not discovered until the foliage thins in the fall, well after the hornets are dead. The European hornet, Vespa, the largest of the hornets, usually nests inside tree hollows.