Above: Bald-Faced Hornet Queen Dolichovespula maculata

Identification

The large, black and white bald-faced hornet, Dolichovespula maculata is not a true hornet; hornets belong to the genus Vespa. Bald-faced hornets are more closely related to wasps called yellowjackets in the genus Vespula. Bald-faced hornets build colonies inside large enclosed carton nests that hang from trees, bushes, low vegetation and occasionally from buildings. A single mated queen starts a new nest each spring by laying eggs inside a small carton nest. The eggs turn into larvae and the queen feeds these larvae until they become pupae and then workers. It is the workers that gradually expand the size of this nest until it is larger than a basketball by the end of the summer season.

Workers can be identified from the large patches of white on their face; this character gives them the name, bald-faced hornet. Their abdomen is mostly black with white markings at the posterior tip. This hornet is the largest endemic yellowjacket in North America and it can build nests containing hundreds of individuals. The single queen is deep inside the nest protected by a retinue of loyal workers.

Biology

Bald-faced hornets are common in both wooded and urban areas in New England. Queens start a new nest each spring after the weather warms up in late April or May. The queen finds loose bark, and other paper strips to start a small nest into which she places her eggs. She adds saliva to the paper bark and forms a smooth carton. When painted wood is used to make carton, you can see the color on the outside of the carton nest.

Inside the carton are horizontal layers of comb or hornet cells divided into circular platforms. The outer carton shell is very thin. This means that if this nest is accidentally damaged from the outside by an animal, the paper covering is easily stripped away and a large number of angry, aggressive wasps fly directly toward the intruder and begin to sting. Since the sting is not barbed, a single hornet can deliver a series of painful stings. It is the venom in the sting that is the cause of the pain. Once a victim is stung, the best response is to distance oneself from the hornet nest as quickly and as far apart as possible. Multiple stings often occur close to a nest.

Workers are beneficial in nature, bringing back many caterpillars and other insect prey to the nest. Its historical enemy is the bear and raccoon, and thus these wasps have a very strong sting and aggressive response to protect the nest.

Control

Since there is always a danger from anaphylactic shock from the venom of a hornet, it is good policy to leave pest control of colonies to a professional. Try to find hornet nests as soon as possible in the spring and summer because they only become larger and more aggressive with time. At the end of the season, the carton nest often remains hanging from a tree but the workers have all died out and the newly mated queens have left the nest to over-winter behind the bark of trees.