This species is a yellow jacket wasp, not a true hornet. Colonies contain 400 to 700 workers. It builds a characteristic large hanging paper nest up to (23 in) in length. Workers aggressively defend their nest by repeatedly stinging invaders. Nests are layered hexagonal combs covered by a mottled gray paper envelope. Bald-Faced Hornets create this paper envelope by collecting and chewing naturally occurring fibers. The wood fiber mixes with their saliva to become a pulpy substance that they can then form into place. Bald-faced hornets are omnivorous, and are considered to be beneficial due to their predation of flies, caterpillars, and spiders. However, their aggressively defensive nature makes them a threat to humans who wander too close to a nest or when a nest is constructed too close to human habitation. They vigorously defend the nest, with workers stinging repeatedly, as is common among social bees and wasps. However, the baldfaced hornet has a unique defense in that it can squirt venom from the stinger into the eyes of nest intruders. The venom causes immediate watering of the eyes and temporary blindness.
Service area's in Illinois includes: Orland Park, Orland Hills, Tinley Park, Oak Forest, Palos Heights, Palos Hills, Palos Park, Matteson, Flossmoor, Olyimpia fields, Country Club Hills, Harvey, Markham, Midlothian, Crestwood, Hazel Crest, Alsip, South Holland, Homewood, Lansing, Forest Park, Richton Park, Crete, Glenwood, Saulk Village, Chicago Heights, Posen, Blue Island, Beverly Chicago. Will counties Joliet and suburbs and in Shorewood, Lockport IL., New Lenox, Mokena, Frankfort IL., Frankfort Square, Homer Glen, Manteno, Peotone, Green Garden, University Park, Indiana's Lake County, Dyer, Schererville, St. John, Lowell, Cedar Lake, Munster, Crown Point, Griffith, Merrillville, IN., Valparaiso, and Winfield IN. Area in Cook county Illinois, Will County Illinois , and Lake County Indiana. .