a cone shaped wasp nest hanging from a roof - hornet nest

Baldfaced hornet nest. Photo: M. Talabac, UME

Updated: May 1, 2024

Key points about social wasps

  • Maryland is home to over one thousand wasp species. Wasps are grouped into two categories: solitary or social. Very few are social; the majority are solitary. Maryland’s social wasps include yellowjackets, hornets, and paper wasps.
  • Social wasps differ from solitary wasps by living in a community of a single nest housing dozens or thousands of members. The wasps in these communities work together to build the nest, find food, raise the young, and defend the nest against perceived threats. 
  • Social wasps do not seek people out just to sting them. They capture prey with their jaws and do not rely on their sting. They only use their stinger when a nest is being defended or when workers are protecting themselves or their food source from a perceived threat. If you are concerned about a risk of stings and a nest cannot be avoided until a killing frost in late autumn (when the nest will cease to be threatening), you may need to have it removed. Refer to the Management section below. 
  • Social wasp colonies only last one year, dying off each winter. Old nests are not reused. Only a handful of fertilized queens overwinter, starting a new nest from scratch each spring.

Social wasp behavior

a flying yellowjack is carrying food in its mouth
Yellowjacket bringing a morsel of food back to the nest. Source: Pixabay


  • Adult wasps consume a liquid diet and are attracted to sugary substances. They feed on flower nectar, fruit juices, oozing sap, honeydew excreted by sap-feeding insects, and nutritional liquids produced by their young.
  • Insects, other invertebrate prey (such as spiders or worms), and carrion (dead animals) are scavenged or hunted by adult wasps as food for their young (larvae). Captured food is typically chewed into smaller pieces and then flown back to the colony. Although adults might ingest juices from the prey item, it is not the primary food source of adults.


  • Nests are built out of a paper-like material that wasps make using chewed-up wood pulp and saliva. This material forms the brood cells (the honeycomb-shaped structure the larvae live in) and the nest envelope (covering). Worker wasps enlarge the nest with additional comb and paper layers as the colony grows. Pulp from different wood sources can result in paper bands of a different color.
  • Nests are located in sheltered hollows (such as tree cavities or wall voids), under building eaves or tree branches, or in the ground (such as in an old rodent burrow), depending on the wasp species. They do not excavate nesting sites, but find and utilize pre-existing locations that suit their needs. Wasps that nest in trees do not cause the tree significant damage, but the collection of nesting material may injure a few branches.
  • The nest population grows in number throughout the season, with only a handful of individuals in spring and potentially hundreds by autumn. All nest members are female until the colony is ready to reproduce.

Life cycle of a colony

a wasp - hornet - building a nest
European hornet queen beginning a new nest in spring. Source: Pixabay
  • Spring: As the weather warms, reproductive females, called queens, emerge from a hibernation-like state and search for a suitable nest site. Each wasp queen works alone and begins nest construction and raising the first generation of workers by herself. All worker wasps are sterile females.
  • Summer: Workers take over nest construction duties as well as foraging for food, and the queen remains in the nest to lay eggs for future generations of workers. The nest population gradually increases until it reaches its largest number of wasps by late summer or early autumn.
  • Late summer into autumn: Some of the larvae raised become new queens and males instead of workers, and they leave the nest to find mates. Males die soon afterward, while the queens search for a sheltered location to overwinter by themselves, such as under a fallen log or in a tree crevice. The social order of the nest may begin to break down, and the workers might be more easily agitated and defensive of a disturbed nest.
  • Winter: Freezing weather ends any remaining nest activity. The original queen from spring, all of the female workers, and all of the males die. Young mated queens have left the nest and are inactive, overwintering elsewhere (leaf litter, tree bark, compost piles, logs, soil cavities, wall voids). The nest will not be re-used.
inside of a a European Hornet nest showing layers of brood cells stacked one on top of the other
Hornet nest structure, with the inner layers of comb and outer covering (partially removed for viewing). Source: Pixabay

Identifying hornets, yellowjackets, and paper wasps

All wasps have a pair of compound eyes, a pair of antennae, six pairs of legs, two pairs of wings, and a narrow “waist” (petiole: area where the thorax and abdomen join). Wasp color patterns can help identify the species highlighted on this page. The coloration of the three main body segments (head, thorax, abdomen) are the key areas used to make comparisons. In some cases, the coloration of legs or antennae can also be helpful.

a diagram of an insect showing the main body parts - head - thorax - abdomen - wings - legs - antennae
Insect diagram by C.Carignan, UME, adapted from Canva artwork

Hornets in Maryland

Only the European hornet and baldfaced hornet occur in Maryland.

European hornet

the black knobs on the abdomen of this wasp indicate it is a European Hornet
European hornet. Photo: M. Talabac, UME

European hornet (Vespa crabro) 

This is the only true hornet established in the U.S. They are non-native, but have lived in North America for over a hundred years.


  • Relatively large among social wasps, ranging from ¾ to 1 ⅜ inches long. Due to size, it might be mistaken for a Northern giant hornet or the eastern cicada killer wasps
  • Body colors are brick-hued reddish-brown with golden yellow on the abdomen and face, with darker markings on the thorax and abdomen. Teardrop-shaped marks on the abdomen are distinctive.
the abdomen of a European Hornet has black teardrops on it
Abdomen of a European hornet. Photo: Allan Smith-Pardo, Invasive Hornets, USDA APHIS PPQ, Bugwood.org

Nest traits

  • Usually tan-brown in color and relatively fragile.
  • Located in concealed sites, such as hollow trees, barns, outbuildings, wall voids, attics, and abandoned honey bee hives.
  • At peak population, most nests may contain about 200 to 400 workers; larger nests can contain over 1,000 workers.

Notable behavior

  • Often observed preying on other pollinators by hunting around flowering plants. Prey can include grasshoppers, flies, and bees, as well as other wasps, plus a variety of additional species.
  • Can fly both day and night. Like many night-active (nocturnal) insects, this wasp may be attracted to outdoor lights (porch lights, landscape accent lighting, and light leaking through window blinds or curtains) and can accidentally collide with windows as a result. They may also be attracted to light from a flashlight.
  • Chews bark off of young tree or shrub branches in order to cause sap to flow. May ingest the sap directly, catch insects drawn to the sap, and/or use the wood pulp for nest building. Common targets include lilac, viburnum, rhododendron and birch. If extensive girdling (damage to sapwood encircling the branch) occurs, the branch may die back to that point, but overall, shrubs and trees are usually not seriously harmed by hornet activity.
two hornets chewing off bark from a branch
European hornets. Photo: Joe Boggs, OSU Extension

Baldfaced hornet

a black and white wasp - baldfaced hornet
Worker scraping off wood pulp for nest-building. Photo: M. Talabac, UME

Baldfaced hornet (Dolichovespula maculata)

Despite its common name, this is a type of “aerial” yellowjacket (one of 7 to 8 such species in North America), not a true hornet. They are native to the U.S. and widespread in Maryland.


  • Medium-sized among social wasps, ranging from ⅝ to ¾ of an inch long for workers and just over an inch for queens.
  • Body colors are black and white, with a white face.

Nest traits

  • Usually light gray in color, but may include a mix of gray and light brown stripes.
  • The main entrance is the lowest and most prominent opening in the cone- or egg-shaped nest, but other arched openings around the top of the dome also give wasps access to the interior. A relatively new nest may have a long entrance tube extending downwards.
  • Nests are built out in the open, with combs surrounded completely by a paper envelope. They can be surprisingly easy to miss, given their eventual size, until winter reveals their presence. Nests may hang from a tree branch, potentially up to 60 feet or more high in the canopy, or be attached at least 3 feet high to a building overhang, wall, or utility pole.
  • At peak population, nests may contain about 100 to 400 workers.

Hornets not in Maryland

Northern giant hornet and yellow-legged hornet are included for reference and comparison, since distant states have had isolated detections of these species. Neither species has been found in Maryland or neighboring states.

Northern giant hornet

wasp with straight dark bands on the abdomen - Northern giant hornet
Photo: Karla Salp, Washington State Department of Agriculture, Bugwood.org

Northern giant hornet (Vespa mandarinia)

In the United States, this non-native hornet has not been found outside of Washington state. This wasp is native to Asia but was first found in British Columbia, Canada, and in Washington State in the fall and winter of 2019. Washington set up a baited trap system for surveying populations of this pest, and occasional isolated detections of additional hornet individuals or nests have occurred in the years following. Located nests are eradicated.

Given their large size, European hornets (social wasps) and Eastern cicada killers (solitary wasps) are often misidentified as this species. If you think you have found this hornet outside of Washington, it is likely one of the similar species above. After reviewing the identification materials on this page, if you think you have encountered a Northern giant hornet, please send a photo of the wasp to your local Extension office or submit it to Ask Extension.


  • The largest hornet in the world, ranging from 1½ - 2  inches long for workers and  up to 2¼ inches long for queens.
  • Body colors are golden-yellow, black, and dark brownish-black. The head is entirely yellow and the dark banding on the abdomen lacks the teardrop or triangular-shaped markings present on the European hornet.

Nest traits

  • Nests are typically made underground in abandoned rodent burrows or sometimes in dead, hollow tree trunks or hollows between roots. Aerial nests are rare.
  • At peak population, nests may contain about 300 or more workers.

Notable behavior

  • Workers are usually solitary hunters, but may team-up to attack other social wasp nests or honey bee hives, especially later in the season when workers are abundant.
  • Has a reputation for preying on honey bee colonies.
    • Northern giant hornets have three different attack phases: hunting phase, slaughter phase, and occupation phase. What triggers this shift in behavior (attack phases) is still unknown. 
    • During the hunting phase, hornet workers will catch and kill individual bees (mainly guard bees and scouts) outside the hive. They pull apart the bee to access the thorax (the body segment powering wings and legs) because it is a rich energy source for the hornet larvae. If a honey bee nest is found, the hornet will scent-mark the nest to potentially return with more workers at a later time.
    • During the slaughter phase, multiple worker hornets will target one particular honey bee hive. In this phase, up to 50 hornets will wait near the entrance of the hive and will bite to death each bee that approaches them. Unlike other attacks, they will not take any part of these bees back to their hive, but will drop the killed bee and wait for the next one. 
    • Once the attacked honey bee hive is defeated, the occupation phase begins where the hornets will enter the hive and raid the comb; taking the protein-rich parts of the bee pupae and larvae back to their nest. Honey is rarely taken back to the hornet nest. Hornets will guard the honey bee hive from other hornets, people, and animals while taking resources back to their nest.
  • Despite the sensationalized nickname “murder hornet,” Northern giant hornets are typically not aggressive toward humans, but will sting if handled or defending a nest. Use extreme caution near northern giant hornets. Like other hornets and wasps, they can sting multiple times.
  • A Northern giant hornet sting is described as being extremely painful, due to stinger size and the volume of venom delivered per sting. However, it is not clear if they are more likely to cause death or induce an allergic reaction than honey bees, yellowjackets, and other social wasps.

Yellow-legged hornet

a wasp with yellow legs
Yellow-legged hornet perched on lichen. Photo: Gilles San Martin, CC BY-SA 2.0

Yellow-legged hornet (Vespa velutina)

This non-native hornet has not been found in the Mid-Atlantic region. The first detection of this species in the U.S. was in Savannah, Georgia, in August 2023, followed by another in South Carolina in November 2023. Their native range is tropical and subtropical areas of Southeast Asia, though they were accidentally introduced to Europe in the early 2000s. As per routine procedure for new and potentially invasive species, the United States Department of Agriculture Animal and Plant Health Inspection Service (USDA-APHIS) is working with the Georgia Department of Agriculture, the University of Georgia, and Clemson University to identify, trap, track, and eradicate these hornets.

European hornets might be misidentified as this species due to their similar size and coloration. If you think you have encountered a yellow-legged hornet, please send a clear photo of the wasp to your local Extension office or submit it to Ask Extension.


  • Somewhat large among social wasps, ranging from 3⁄4 to 1¼ inches long for queens. Early-season workers are relatively small at about ½ inch, with later generations nearing the size of a queen by the end of the season. 
  • Body colors are variable (multiple color morphs exist), but only one color morph (form) has been introduced outside of Asia. This introduced color morph is primarily a mix of near-black and golden-yellow. The face is yellow; the rest of the head is black. Lacks the distinctive teardrop-shaped markings on the abdomen of the European hornet. The lower portions of the legs are yellow.

Nest traits

  • The nest is similar in appearance to that of a baldfaced hornet.
  • Nests are built out in the open, hanging from a tree branch, with combs surrounded completely by a paper envelope.
  • Two nests are built during the course of a growing season. The first is more irregular in shape and houses only the first generations of workers the queen produces. Later in summer, the colony builds and moves into a separate secondary nest which is usually higher off the ground and the typical egg shape.
  • At peak population, nests may contain about 400 workers. In its native range, where the climate is warmer, populations for a single nest can average thousands of workers.

Notable behavior

  • Uses a “bee hawking” behavior similar to the predation on honey bees of the Northern giant hornet. Prey preference includes bees, other wasps, and flies. Workers may hunt around pollinator-attracting flowers, near honey bee hives, or around dead animals that attract flies.
a wasp near a honeybee hive
Yellow-legged Hornet at the entrance to a honey bee hive. Photo: Danel Solabarrieta


Several species of yellowjacket occur in Maryland. Except for the German yellowjacket (Vespula germanica), most (if not all) other species are native to Maryland.

wasp with yellow and black stripes and yellow band around face - yellowjacket
Eastern Yellowjacket (Vespula maculifrons). Photo: Johnny N. Dell, Bugwood.org


  • Small among social wasps, ranging from ⅜ to ⅝ of an inch long, with queens a bit larger than workers.
  • Body colors are black and yellow, and pattern details on the thorax and abdomen vary slightly between species. Southern yellowjacket queens in particular have an orange-yellow abdomen with sparser black markings.
  • Although they are not completely hairless, yellowjackets have much less body hair than a honey bee.

Nest traits

  • Nest location varies based on species: some nest in the ground (such as in an old rodent or rabbit burrow), some attach a nest to the branches of dense shrubs, and others nest in wall voids or sheds.
  • A gray-brown paper envelope covers the nest, but due to its secluded location, it is not often seen unless a nest is accidentally exposed.
  • At peak population, large nests may contain thousands of workers.
two wasps emerging from a ground nest
Underground nest entrance hole of German yellowjackets (Vespula germanica). Photo: Mary C Legg, Bugwood.org

Notable behavior

  • Has a reputation for being easily agitated, so may appear to sting without provocation. Attacking yellowjackets release an alarm pheromone that encourages nestmates to defend the nest if the threat does not leave the area. Vibrations near a nest, such as from a lawn mower or electric hedge clippers, can trigger a defensive response.
  • Southern yellowjacket queens sometimes take over the young spring nests of other yellowjacket species, killing the original queen and laying their own eggs. Eventually, only her workers reside in the nest as the original generations from the first species die off.

Paper wasps

a wasp with a reddish abdomen and yellow stripes - paper wasp
Paper wasp (Polistes sp.). Photo: Russ Ottens, University of Georgia, Bugwood.org

Several species of paper wasp (genus Polistes) occur in Maryland. Except for the European paper wasp (Polistes dominula), which originated in Eurasia, most (if not all) other species are native to Maryland.


  • Medium-sized among social wasps, ranging from ⅝ of an inch to nearly 1 inch long. Queens are the same size as workers. May look larger in flight due to long dangling legs.
  • Body colors vary between species and typically include yellow, brick-hued reddish-brown, and near-black. In comparison to hornets and yellowjackets, paper wasps generally have less yellow in their coloration and their legs are relatively long.
  • The longer antennae of male paper wasps tend to have curved tips, and their faces are usually more yellow compared to females (an exception is the ringed paper wasp, Polistes annularis).
  • The European paper wasp has antennae that are mostly orange in color, unique among paper wasps. Although superficially similar to a yellowjacket in size and body color pattern, its antenna color is distinctive.
black and yellow paper wasp
European paper wasp. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org

Nest traits

  • The single layer of comb, usually only a few inches across, is exposed and not covered by an envelope like yellowjacket nests. The papery material is a brown-gray color, and the nest has an umbrella-like shape.
  • The central stalk atop the nest is attached to shrub branches or perennial plant stems, building eaves or door frames, or any protected location.
  • At peak population, nests may contain around 20-75 members.

Notable behavior

  • Not as defensive of a nest as hornets and yellowjackets. May deliberately bump into an intruder as a warning before resorting to stinging.
  • Can be semi-social, where several egg-laying females can share a single nest after developing a hierarchy of dominance. Nests contain a mix of workers and one or more queens, especially later in the season, with the “foundress” (the original nest builder) being the queen laying most of the eggs.
  • The Northern paper wasp (Polistes fuscatus) appears to have the ability to recognize the unique facial patterns of other individuals. Researchers speculate that this helps reduce conflicts in a nest once dominance has been established among its members.
  • Overwintering females (young queens) might form aggregations, where they gather in groups in protected areas.

Comparisons for identification

a diagram comparing 8 wasps - 6 found in Maryland and 2 not in Maryland
Download PDF - Wasp Identification Guide

Managing conflicts with wasps and their nests

Social wasps tend to be non-confrontational and not aggressive unless a nest is disturbed or an individual feels threatened (like being swatted or caught). If a threat is perceived, wasps may sting, and individual wasps are capable of stinging repeatedly, unlike honey bees.

  • Leave nests alone to avoid triggering a defensive response. Do not mow directly under a nest, strike a tree or wall containing a nest, or shine a light at the nest entrance. Avoid reaching into crevices and openings you cannot see into.
  • Remove or cover-up attractants. Foraging wasps will explore human food if given the opportunity, like sugary beverages, candy, fruit, and even meat. This is especially the case in the autumn, when there are fewer flowering plants and sources of nectar. Consider adding fall-blooming plants to your landscape to distract wasps from a picnic or cookout. Keep outdoor food and beverages covered, rake up and discard fallen tree fruit, and equip trash cans with tight-fitting lids. Scented soaps, shampoos, perfume, or cologne can also attract foraging wasps.
  • Avoid direct contact. Wasps sting when they feel threatened, which includes being handled, swatted, or smacked. Some threatened wasps release a scent marker that will attract more nestmates as reinforcements. When you come across a wasp outside its nest, calmly walk away, remove or cover attractants, and/or gently move them along with a piece of paper or longer object.
  • Turn off outdoor lighting where possible, or switch to motion-activated lights. Reducing artificial light will not only keep European hornets from being attracted to the light source itself, but it will deprive them of an easy hunting ground as light attracts many different insect species. LED bulbs with a warmer color temperature (yellower-looking light) have been shown to attract fewer insects overall compared to bluish-white light, but they still might appeal to certain insects (like earwigs).
  • Pesticide use should be the last resort. When a nest cannot be avoided until its natural demise (first hard frost), the use of a dust or an aerosol wasp spray may be needed. Follow all product label directions carefully so it is as effective as possible while reducing the risk of stings. Hire a pest control professional if you do not feel comfortable treating a nest yourself, or if a nest is hard to reach. The full impact of a pesticide treatment may take several days to achieve since the application residues need to contact workers coming and going from the nest.
  • Do not attempt to use a home remedy (flooding a burrow, setting a nest on fire, etc.). They are not necessarily going to be effective, and are likely to increase the risk of stings as the agitated wasps escape or as other colony members return from a foraging trip and detect a threat.
  • For nests built inside walls, try to have the inactive nest remnants removed so dead larvae do not attract flesh flies and rodents. Old nests in natural settings, such as in a tree, do not need to be removed. Any remaining prey in the nest becomes food for wildlife. The weather and foraging wild animals will eventually disintegrate the nest.

Additional resources


Sheehan, Michael J. and Tibbetts, Elizabeth A. "Specialized Face Learning Is Associated with Individual Recognition in Paper Wasps." Science, vol. 334, no. 6060, 2011, pp. 1272-1275.

Tibbetts, Elizabeth A. and Sheehan, Michael J. “Individual Recognition and the Evolution of Learning and Memory in Polistes Paper Wasps.” Handbook of Behavioral Neuroscience, vol. 22, 2013, pp. 561-571.

Author: Miri Talabac, Horticulture Coordinator, Home and Garden Information Center, January 2024. Reviewed by Madeline Potter, Faculty Specialist/Entomology & Integrated Pest Management; and Christa Carignan, Coordinator, Digital Horticulture Education, University of Maryland Extension, April 2024.

Still have a question? Contact us at Ask Extension.