Bald-faced Hornet

hornet

The large, black and white bald-faced hornet (sometimes referred to as the white-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.

hornetnest

Active arboreal nest

Identification more photos

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.

hornetlarvae

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.

nest

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 wood color on the outside of the carton nest.

horneteggs

Inside the carton are horizontal layers of comb or wasp cells divided into circular platforms, each platform larger than the previous. The outer carton shell is very paper 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 wasp 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 wasp nest as quickly and as far apart as possible. Multiple stings often occur close to a nest.

hornetcomb

Nests can be located in a tree, high off the ground, in low bushes and against buildings under overhangs. Nests are often covered with leaves and are very difficult to see. 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.

hornetcomb1

Control

Under most circumstances the nest is located far from adults, children and people with allergies to stings. If the nest is in a dangerous location and the decision is made to remove the nest, caution is in order before trying to do this yourself. Following directions to spray a chemical inside the nest at night may have negative effects as wasps fly out on warm evenings and begin to attack. If you run out of chemicals before you run out of wasps, you have increased the risk from stings.

hornetworker

Since there is always a danger from anaphylactic shock from the venom of a wasp, it is good policy to leave pest control of colonies to a professional. Try to find wasp nests as soon as possible in the spring and summer because the nests only become larger and the wasps inside more aggressive with time. Professionals often are able to drop the entire nest into a heavy sealed bag and destroy the colony without having a single wasp alerted. 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. Too often people pay to eliminate workers from an old abandoned nest well after the nest is empty for the season.

Developed by Gary D. Alpert Ph.D, Entomologist at Harvard University (retired). Gary is now an Associate at the Museum of Comparative Zoology, Harvard University.

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