Maryland is home to more than a thousand species of wasps, yet most people can only name two or three before running out of ideas.
Some of these types of wasps in Maryland build football-sized paper nests in trees, others dig burrows in bare patches of lawn, and a surprising number never sting a person in their entire lives because they are too busy hunting caterpillars, spiders, or beetle grubs. Knowing which wasp is buzzing around a porch or garden bed matters, because the docile mud dauber minding its own business is nothing like the yellowjacket defending an underground colony of a thousand workers.
This guide walks through ten of Maryland’s most recognizable wasps, from the social species that build visible nests to the tiny parasitic wasps most residents never notice at all. For a broader look at how these insects compare across regions, the overview of different types of wasps found across North America offers useful context before diving into Maryland’s specific lineup.
1. Paper Wasps
Paper wasps belong to the genus Polistes, and they are among the easiest social wasps to recognize once someone knows what to look for. According to University of Maryland Extension, Maryland’s social wasps include yellowjackets, hornets, and paper wasps, which differ from solitary wasps by living in a community of a single nest housing dozens or thousands of members.
Their nests give them away instantly. Paper wasps build distinctive, open-comb nests that look like an upside-down umbrella, made from a papery mixture of chewed wood and saliva, completely exposed with visible interior cells and typically suspended from roof eaves, porch ceilings, window frames, or deck railings. Peak colony size stays modest compared to yellowjackets. They build open, umbrella-shaped nests attached by a single stalk to eaves, doorframes, or shrub branches, and University of Maryland Extension research indicates these colonies hold 20 to 75 adults at peak.
Not every paper wasp in the state is native. European Paper Wasps are an invasive species in Maryland, and researchers have found that they often outcompete native paper wasps and negatively affect caterpillars like the Monarch butterfly. The invasive species thrives largely because of how adaptable it is. One reason it has spread across North America is its adaptability, since European Paper Wasps will inhabit almost any habitat, including urban and suburban areas, and are often closely associated with humans, nesting on or in human-made structures.
Pro Tip: Paper wasps rarely sting unless their nest is directly disturbed. If a nest is in a low-traffic spot away from doors or walkways, it is often safer to leave it alone than to knock it down.
2. Yellowjackets
Yellowjackets are the wasps most Marylanders picture when they hear the word “sting.” These compact wasps measure 3/8 to 5/8 inch with bright yellow and black markings and smooth bodies, which sets them apart from the fuzzier bees they are frequently confused with.
Nesting habits explain much of their reputation for aggression. They nest underground, in wall voids, or sometimes in shrubs, and colonies can reach several thousand workers by late summer, getting very aggressive when disturbed; lawn mower vibrations often set off ground-nesting colonies. A single triggered nest can respond fast and in force. Large yellow jacket colonies may have over 1,000 workers ready to defend the nest, and when alarm scents are released, the whole colony can come out in minutes, delivering dangerous amounts of venom even to people without allergies.
Colonies do not persist year after year in the same spot. Only fertilized queens survive winter by hiding in leaf litter, logs, or building gaps, meaning each spring starts a fresh colony from scratch. Neighboring states report similar patterns, and the wasps found in New Jersey include several of the same aggressive ground-nesting yellowjacket species that trouble Maryland yards.
Important Note: Multiple yellowjacket stings can deliver a large dose of venom quickly. Anyone who develops swelling beyond the sting site, difficulty breathing, or dizziness after a sting should seek medical attention promptly, since these can be signs of an allergic reaction.
3. Bald-Faced Hornets
Despite the name, bald-faced hornets are not true hornets at all. Bald-faced hornets are actually large yellow jackets with black and white coloring, a fact that surprises many people who assume any large black-and-white stinging insect must belong to a different family entirely. The scientific name for this species is Dolichovespula maculata, and its nest is one of the more dramatic sights in a Maryland backyard. They build big, gray, football-shaped nests that hang 3 to 60 feet up in trees or on building overhangs, and colonies hold 100 to 400 workers that will defend the nest aggressively.
Because the nests are enclosed and papery rather than open like a paper wasp’s comb, they are hard to mistake once spotted. According to University of Maryland Extension, bald-faced hornets are among the common wasps homeowners need to identify and manage correctly, alongside yellowjackets, European hornets, and paper wasps. Readers dealing with similar aerial nests in the upper Midwest may recognize overlap with the wasps documented in Minnesota, where the same species builds comparable football-shaped nests.
4. European Hornets
European hornets, scientific name Vespa crabro, are the largest true hornets found in Maryland and were introduced from Europe well over a century ago. They are frequently mistaken for far more dangerous insects, which makes accurate identification worth the effort. State entomologists have gone out of their way to clear up one common source of panic. The Northern giant hornet (“murder hornet”) and yellow-legged hornet are not present in Maryland, according to University of Maryland Extension. Any large, reddish-brown and yellow hornet spotted in the state is almost certainly the European hornet rather than an invasive species making headlines elsewhere.
European hornets tend to nest in hollow trees, wall voids, or other enclosed cavities rather than in the open, and they are unusual among Maryland’s social wasps for being active after dark, often bumping against lit windows on summer nights while hunting other insects. Their diet leans heavily toward other insects, including cicadas and large moths, which puts them in a similar ecological role to some of the solitary hunters covered later in this guide. Readers curious about how hornet populations compare across the region can also look at the wasp species recorded in Ohio, where European hornets follow a nearly identical nesting and hunting pattern.
5. Mud Daubers
Mud daubers could not be more different from the social wasps described so far. Mud daubers are lesser-known compared to other types of wasps, as they travel alone to build mud nests, and are usually black in color with very thin “thread waists,” referring to the long segment between the thorax and abdomen.
Their solitary lifestyle changes everything about how they behave around people. As solitary wasps, mud daubers do not live in colonies; instead, they plaster small, tube-like mud structures against flat, sheltered surfaces, and these hard, clay nests resemble organ pipes or small finger-sized tubes, frequently found on garage walls, brick siding, sheds, and protected porch rafters. Two common Maryland species fit this description well: the black-and-yellow mud dauber, Sceliphron caementarium, and the metallic blue mud dauber, Chalybion caeruleum, which often reuses old nests built by other mud daubers.
Because each female works alone and has no colony to protect, mud daubers rarely act defensively even when a nest is disturbed. Gardeners in the Midwest see a similar pattern among the wasps found throughout Iowa, where solitary mud-nesting species are likewise considered some of the least aggressive wasps around structures.
6. Sand Wasps
Sand wasps, genus Bembix, favor bare, sandy ground rather than trees or eaves, and they are easy to overlook until someone notices dozens of small holes clustered together in a patch of loose soil. Per the Utah State University Extension IPM notes, sand wasps measure 3/4 to 1 5/8 inches long, are black with yellowish markings, some have bright green eyes, and lack the hairs typical of bees.
Their nesting style sits somewhere between solitary and social behavior. Sand wasps are solitary, but often nest together in favorable sandy sites in the ground rather than forming true colonies, and their diet consists of nectar and pollen. Despite the intimidating aggregations, the same extension source notes that nests pose a minimal health risk to humans, since the wasps can give a painful sting but are not aggressive.
Anyone who has watched wasps patrol a sandy garden bed in the Pacific Northwest will recognize similar behavior among the wasp species active in Oregon, where sand wasps favor the same kind of bare, well-drained soil found in parts of Maryland’s coastal plain.
7. Cicada Killer Wasps
Few Maryland insects draw more startled reactions than the cicada killer, Sphecius speciosus. Its size alone explains the alarm: according to the University of Kentucky Extension, cicada killers are large, imposing wasps, with females nearly 2 inches long and males around 1.5 inches.
Color and markings make identification straightforward once the size registers. Cicada killers have orange legs and wings and black and yellow abdomens with distinctive bands, and adults are most active during peak cicada season. Adult wasps are most commonly seen in July and August, which lines up with when annual cicadas start calling from Maryland’s trees. Despite their size, cicada killers rarely bother people. Despite their large size, cicada killers are not considered stinging hazards unless they are directly disturbed, and control is not necessary or typically feasible. The behavior split between sexes is worth knowing before panicking at a hovering wasp. Female cicada killers are equipped with a stinger used to inject venom into a cicada, while male cicada killers do not have a stinger and instead carry a non-stinging pseudostinger.
Pro Tip: Large males hovering at eye level near a lawn are simply patrolling for females and cannot sting at all. The real giveaway of a cicada killer colony is a mound of loose sand or soil piled near a burrow entrance, not aggressive swarming.
Homeowners further west deal with the same large-bodied burrower. The wasps recorded across Missouri include cicada killers that follow an identical summer emergence pattern in sandy lawns and garden beds.
8. Four-Toothed Mason Wasps
The four-toothed mason wasp, scientific name Monobia quadridens, is one of Maryland’s most misidentified solitary wasps. At first glance, they are often confused with the more territorial Bald-faced Hornet, but Four-toothed Mason Wasps are solitary, docile wasps in Maryland that don’t even defend their nests.
Their sting risk is minimal but not zero. The females can sting if handled, and it is said to be comparable to a Bald-faced Hornet’s sting, while males lack stingers but will jab with the pointy end of their abdomen, which feels more like a pin-prick.
Their nesting behavior connects directly to another group covered later in this list. Females typically build their nests in existing holes, beginning by crawling into the tunnel’s far end and laying an egg, then hunting caterpillars, paralyzing them with a sting and placing them in front of the egg for the larva to eat when it hatches. Once satisfied with the food supply, the female seals off the chamber and moves to the next section of the tunnel. Gardeners tracking caterpillar populations may find it useful to compare notes with the guide to caterpillars found in Maryland, several of which serve as prey for these wasps.
9. Braconid Wasps
Braconid wasps rarely get noticed because most species are tiny, non-stinging, and spend their lives inside or on other insects rather than buzzing around porches. They belong to the family Braconidae, and Maryland’s checklist of these parasitoid wasps is enormous compared to the handful of social species most residents can name.
The scale of this diversity comes from state-level tracking efforts. Maryland documents all its wasp species online through the Maryland Biodiversity Project, a citizen science initiative that has logged over 1,500 wasp species, with close to three-quarters of them falling into the superfamily Ichneumonoidea, which includes Braconid and Ichneumonid wasps known for their large ovipositors.
Braconid wasps also do real work as biological pest control. Researchers use data on these species to determine which might be useful as pest control agents, and Maryland used a Braconid wasp species to evaluate whether it could establish a continuous predatory presence against emerald ash borer larvae, a finding published in the journal Biological Control in 2016.
Key Insight: Braconid wasps are a major reason emerald ash borer damage has not been worse across the mid-Atlantic. Their larvae develop inside beetle grubs, killing the pest before it can bore further into ash trees. Anyone researching the beetles themselves can find more detail in the guide to beetles found in Maryland, including the emerald ash borer this wasp targets.
10. Ichneumonid Wasps
Ichneumonid wasps make up the other half of the ovipositor-bearing superfamily that dominates Maryland’s wasp checklist, and several species are large enough to startle anyone who stumbles across one on a tree trunk. The family Ichneumonidae contains parasitoid species that target beetle larvae, moth caterpillars, and other insects hidden inside wood or soil. One species stands out as a relatively easy identification.
The Black Giant Ichneumonid Wasp has a yellow face, yellow antenna, and an ovipositor that can reach five inches in length, all useful identification clues. That long, thread-like appendage is not a stinger at all, but a drilling tool the female uses to reach beetle larvae tunneling deep inside dead or dying wood.
Practically speaking, most of the state’s ichneumonid diversity is invisible to the average resident. Only entomologists with the proper tools could identify all of Maryland’s documented wasp species, which is a reminder that the loud, visible wasps covered earlier in this guide represent a small fraction of the insects actually classified as wasps.
For readers who want reassurance about which local insects pose no threat at all, the roundup of insects that are not poisonous covers many of these harmless parasitoid species alongside other misunderstood bugs.
Recognizing Maryland’s Wasps at a Glance
With ten distinct groups covered, a side-by-side comparison helps clarify which wasps are worth watching for around the home and which are essentially harmless.
| Wasp Type | Lifestyle | Typical Nest | Sting Risk to Humans |
|---|---|---|---|
| Paper Wasps | Social | Open umbrella comb under eaves | Low unless nest disturbed |
| Yellowjackets | Social | Underground or wall voids | High, especially late summer |
| Bald-Faced Hornets | Social | Enclosed football-shaped, in trees | Moderate to high near nest |
| European Hornets | Social | Hollow trees, wall cavities | Moderate, mostly at night |
| Mud Daubers | Solitary | Mud tubes on flat surfaces | Very low |
| Sand Wasps | Solitary/aggregating | Burrows in bare sand | Low |
| Cicada Killer Wasps | Solitary | Burrows in sandy lawns | Very low |
| Four-Toothed Mason Wasps | Solitary | Existing holes sealed with mud | Very low |
| Braconid Wasps | Parasitoid | Inside host insects | None (no stinger for humans) |
| Ichneumonid Wasps | Parasitoid | Drilled into wood or hosts | None (ovipositor, not a stinger) |
A few patterns stand out from this comparison. The wasps most likely to sting defensively are the social species that live in colonies large enough to need active defense, while solitary hunters and parasitoids generally pose little to no risk because they have no nest full of relatives to protect. Anyone comparing notes with other stinging insects around the yard may also want to check the guide to ants found in Maryland, since several ant species share nesting habits or defensive behavior with the ground-dwelling wasps covered here.
Living Alongside Maryland’s Wasps
Most of the wasps on this list do far more good than harm, whether that means pollinating flowers, hunting garden pests, or quietly controlling beetle populations that would otherwise damage trees across the state. The handful of social species capable of painful, repeated stings, mainly yellowjackets and bald-faced hornets, deserve caution around active nests, but the majority of Maryland’s thousand-plus wasp species will never sting a person at all.
Learning to tell a docile mud dauber from an aggressive yellowjacket, or a harmless mason wasp from a territorial hornet, makes it far easier to share a backyard with these insects without unnecessary fear. Readers interested in how Maryland’s insect diversity compares to other states can continue exploring with the overview of spiders found in Maryland, another group of misunderstood arthropods that plays a similar pest-control role in local ecosystems.