Maryland is home to several wasp species that become increasingly visible from spring through fall. The most common are yellowjackets, paper wasps, bald-faced hornets, and solitary species like cicada killers and mud daubers. Most are more beneficial than dangerous, feeding on pest insects and pollinating plants, but knowing which species you’re dealing with helps you decide whether to leave a nest alone or take action.
Common Social Wasps in Maryland
The wasps most Marylanders encounter fall into three groups: yellowjackets, paper wasps, and bald-faced hornets. All three are social species, meaning they live in colonies with a queen and workers, and all three can sting multiple times.
Yellowjackets are the small, bright yellow-and-black wasps that show up uninvited at picnics and trash cans. They’re about half an inch long and often nest underground in old rodent burrows, though they also build nests inside wall voids, attics, and hollow logs. Their nests are enclosed in a papery shell, so you typically can’t see the comb structure from outside. Yellowjackets are the most likely to sting you in Maryland because they’re attracted to human food, especially sugary drinks and meat.
Paper wasps are longer and more slender than yellowjackets, with dangling legs visible during flight. They build the classic open, umbrella-shaped nests you find under eaves, porch ceilings, deck railings, and fence posts. These nests have visible hexagonal cells and are usually small, rarely exceeding the size of a fist. Paper wasps are generally less aggressive than yellowjackets and won’t bother you unless you get very close to their nest.
Bald-faced hornets are the largest social wasps in the state, black with white facial markings. They build large, enclosed, football-shaped nests that hang from tree branches, shrubs, or the sides of buildings. These nests can grow quite large by late summer. Bald-faced hornets are highly defensive of their nest and will sting repeatedly if they perceive a threat nearby.
Solitary Wasps: Big but Mostly Harmless
Some of the most intimidating-looking wasps in Maryland are actually the least dangerous. Cicada killer wasps are roughly 1.5 inches long with yellow-and-black banding, and they show up in July and August when annual cicadas are active. They dig burrows in bare, sunny patches of well-drained soil, and sometimes many nests cluster together in the same lawn, which can look alarming. But despite their size, cicada killers are not aggressive toward people. Females use their sting to paralyze cicadas, dragging them into burrows as food for their larvae. Males are territorial and may hover near you, but they physically cannot sting.
Mud daubers are another common solitary wasp. They’re slender, often black or metallic blue, and build small tube-shaped mud nests on walls, under eaves, and in garages. They provision their nests with paralyzed spiders. Mud daubers rarely sting and pose essentially no threat to people.
When Wasps Are Most Active
Wasp activity in Maryland follows a predictable seasonal arc. In spring, queen wasps emerge from overwintering spots like leaf litter, tree bark, compost piles, and wall voids. Each queen starts a new nest alone, laying the first eggs and raising the first batch of workers herself. Colonies at this stage are tiny, just a handful of individuals.
Through June and July, colonies grow steadily as new workers hatch and take over foraging, nest-building, and defense duties. By late summer and into autumn, a single colony can contain hundreds of wasps. This is when you’re most likely to have problems. The colony has reached peak size, workers are foraging aggressively for sugar and protein, and the social order within the nest starts to break down. Workers become more easily agitated and more defensive if the nest is disturbed. Late August through October is the peak window for stings in Maryland.
The first hard freeze ends all remaining nest activity. The original queen, all workers, and all males die. Only newly mated young queens survive, tucking themselves into sheltered spots like soil cavities, under logs, or inside wall voids to wait out winter. Old nests are never reused the following year.
Identifying a Nest on Your Property
Where you find the nest tells you a lot about what you’re dealing with. Paper wasp nests hang in open, sheltered spots: under eaves, porch roofs, window frames, and mailbox covers. They’re small, open-faced, and the wasps sit visibly on the comb. Yellowjacket nests are usually hidden. If you see wasps streaming in and out of a hole in the ground, a gap in your siding, or a crack near your roofline, it’s likely yellowjackets. Bald-faced hornet nests are the easiest to spot from a distance: large, gray, teardrop-shaped structures hanging from branches or building overhangs.
If you find neat round holes about the diameter of a quarter in bare soil, especially in sunny areas of your lawn, those belong to cicada killers. Small mud tubes or clusters on walls and ceilings are mud dauber nests.
What to Do About a Nest
Not every nest needs to be removed. Paper wasp nests tucked under a high eave, away from foot traffic, are generally safe to leave alone. The wasps eat caterpillars and other garden pests. Solitary wasps like cicada killers and mud daubers pose so little risk that removal is rarely justified.
Nests that do warrant action are those near doorways, play areas, or anywhere people regularly pass within a few feet. Yellowjacket ground nests in a lawn where children play, or a paper wasp nest right above your front door, are reasonable candidates for removal. Early in the season, when colonies are small, a paper wasp nest can sometimes be knocked down at night (when wasps are less active) and the area treated to discourage rebuilding. Yellowjacket nests and large bald-faced hornet nests are more dangerous to handle yourself, particularly by late summer when colonies are at peak population and defensiveness. Professional pest control is the safer option for these.
Timing matters. If you discover a nest in October or November and it’s not in a high-traffic area, you can simply wait. Freezing weather will kill the colony, and the nest won’t be reused next year. You can safely remove the empty structure over winter.
Preventing Nests Near Your Home
A few practical steps reduce the chances of wasps establishing nests close to your living spaces. Seal cracks and gaps in siding, soffits, and around window frames in early spring before queens begin scouting for nest sites. Keep outdoor trash cans tightly lidded, since exposed garbage is a major attractant for yellowjackets. Pick up fallen fruit from trees in your yard, and avoid leaving sugary drinks or pet food uncovered outdoors. If you’ve had recurring ground-nesting yellowjacket problems, filling old rodent burrows and improving soil drainage in your yard can help.
Handling a Wasp Sting
A normal wasp sting causes sharp pain, redness, and localized swelling that peaks within a day or two and resolves on its own. Unlike bees, wasps don’t leave a stinger behind, so there’s nothing to scrape out. A cold pack helps with swelling, an over-the-counter antihistamine eases itching, and hydrocortisone cream applied to the site can address both. Some people develop a larger local reaction with swelling that extends several inches from the sting site. This is uncomfortable but not dangerous.
What is dangerous is anaphylaxis, a systemic allergic reaction that affects multiple body systems at once. Warning signs include widespread hives far from the sting site, difficulty breathing, swelling of the throat or tongue, dizziness, and a sudden drop in blood pressure. These symptoms can develop within minutes. If you or someone nearby shows these signs after a sting, call 911 immediately. People with known venom allergies should carry an epinephrine auto-injector and use it at the first sign of a systemic reaction.
The Northern Giant Hornet Question
Many Marylanders have wondered whether the northern giant hornet (sometimes called the “murder hornet”) has reached the state. As of now, this species has not been detected in Maryland. The only confirmed U.S. sightings have been in Washington state, where eradication efforts have been underway since 2019. If you see an unusually large wasp in Maryland, it’s far more likely a cicada killer, a European hornet (which has been established in the eastern U.S. for over a century), or a bald-faced hornet. European hornets are brown and yellow, about an inch long, and sometimes fly at night toward porch lights, which can be startling but is normal behavior for the species.