Pennsylvania is home to more than 400 bee species and dozens of wasp species, ranging from tiny sweat bees you barely notice to large carpenter bees drilling into your deck. Whether you’re trying to identify something buzzing around your yard or figure out what built a nest under your eaves, here’s what you’re likely encountering across the state.
Pennsylvania’s Bee Families at a Glance
The state’s bee diversity breaks down into several major families. The largest is Apidae, with 118 documented species. This family includes honey bees, bumble bees, carpenter bees, long-horned bees, and cuckoo bees. Halictidae, commonly called sweat bees, is the second largest group at 110 species. Mining bees (Andrenidae) account for 100 species, and leafcutter and mason bees (Megachilidae) add another 81. Most bee species in Pennsylvania nest underground, which means many of the bees in your yard are tunneling into bare soil rather than building the hive structures people typically picture.
Honey Bees
Honey bees are the most recognizable bee in Pennsylvania, though they’re not native to North America. They’re cavity nesters, seeking out hollow, enclosed spaces like tree holes. They occasionally move into the walls of homes, which is when most people first become aware they’re nearby. Honey bees reproduce by swarming: a large group of bees leaves an established hive with a queen to find a new home. If you see a dense cluster of bees hanging from a branch or fence post, that’s a swarm. They’re usually not aggressive and will move on to their new nest within about two days.
Bumble Bees
Pennsylvania has 14 species of bumble bees. They’re large, fuzzy, and loud, making them easy to spot on flowers from spring through fall. Unlike honey bees, bumble bee colonies are seasonal. A single queen overwinters alone, then emerges in spring to start a new colony from scratch. They usually nest in underground cavities like abandoned rodent holes, though they sometimes set up in above-ground spots like hay bales. Bumble bees are important pollinators for tomatoes, peppers, and other crops because they “buzz pollinate,” vibrating flowers at a frequency that releases pollen honey bees can’t access.
Carpenter Bees
The eastern carpenter bee is the large, shiny black bee you see hovering near wooden decks, porches, and fascia boards. They drill nearly perfect half-inch holes into untreated or weathered wood to create nesting tunnels. Males are territorial and will hover aggressively near people, but they can’t sting. Females can sting but rarely do. Pennsylvania also has several species of small carpenter bees, which are much less conspicuous and nest in hollow stems and twigs. Both types may be solitary or form loose cooperative groups where several females share a single nest entrance.
Sweat Bees, Mining Bees, and Mason Bees
These three groups make up the bulk of Pennsylvania’s bee diversity, yet most people never learn their names. Sweat bees are small, often metallic green or bronze, and earned their name because some species are attracted to human perspiration. With 110 species in the state, they’re everywhere, pollinating wildflowers and garden plants throughout summer.
Mining bees are ground nesters that create small mounds of excavated soil, sometimes in lawns or garden beds. They look like smaller, fuzzier versions of honey bees and are solitary, meaning each female provisions her own nest. They’re gentle and almost never sting.
Mason bees and leafcutter bees nest in pre-existing cavities: hollow twigs, stems, pine cones, even empty snail shells. Leafcutter bees are the ones responsible for the neat, circular holes you might find cut into rose leaves. They use those leaf pieces to line their nest cells. Both groups are efficient pollinators, and mason bees in particular have become popular among gardeners who install “bee hotels” to attract them.
Yellowjackets
Yellowjackets are the wasps most Pennsylvanians encounter, and the ones responsible for most stings. They typically build nests underground, which is why people often disturb them while mowing or walking through a yard. They also nest at the base of building walls or in cracks in pavement and landscaping. Their nests are made of a papery material they create by chewing wood into pulp.
Yellowjackets are social wasps that become increasingly aggressive in late summer and early fall, when their colonies peak in size and natural food sources decline. That’s when they start showing up at picnics, garbage cans, and outdoor dining areas, drawn to sugary drinks and protein. A colony dies off after the first hard frost, so if you find a nest late in the season and it’s not in a high-traffic area, waiting for cold weather is a practical option.
Paper Wasps
Pennsylvania has two common paper wasp species: the northern paper wasp and the European paper wasp. Both build the open, umbrella-shaped nests you find hanging from eaves, overhangs, porch ceilings, and playground equipment. The cells of the nest are visible from below, giving them a honeycomb appearance. Paper wasps are less aggressive than yellowjackets, but they will sting if you disturb their nest or get too close. Their colonies are smaller, typically a few dozen individuals compared to the hundreds or thousands in a yellowjacket nest.
Like other social wasps, paper wasps chew captured insects into a paste to feed their larvae. Adults mostly eat nectar and other sugary liquids. Their predatory habits make them genuinely useful for garden pest control, since they hunt caterpillars, beetle larvae, and other plant-damaging insects.
Bald-Faced Hornets and European Hornets
Bald-faced hornets are closely related to yellowjackets, despite the “hornet” name. They build large, enclosed paper nests that hang from tree branches or attach to the sides of buildings. These nests can grow to the size of a basketball or larger by late summer, with a single entrance hole at the bottom. Bald-faced hornets are black with white facial markings and are noticeably bigger than yellowjackets. They’re defensive of their nests and can sting multiple times.
European hornets are the only true hornets in Pennsylvania. They’re large, brown and yellow, and sometimes active at night, which sets them apart from most other stinging insects. They nest in cavities like tree hollows and wall voids and build their nests above ground. European hornets can strip bark from shrubs and small trees, which occasionally alarms homeowners, but the damage is typically cosmetic.
Solitary Wasps: Mud Daubers and Cicada Killers
Not all wasps are social. Pennsylvania has many solitary wasp species, and two stand out because of their size and visibility.
Mud daubers build small tubes of dried mud on walls, ceilings, and sheltered surfaces. Inside each tube, the female packs paralyzed spiders as food for her developing larvae. Mud daubers are slender, often black or metallic blue, and are remarkably docile. They almost never sting people, even when you’re standing right next to their nest.
Cicada killers are among the largest wasps in the state, reaching about 1.5 inches long. They dig burrows in sandy or well-drained soil, often in lawns and garden beds, leaving visible mounds of excavated dirt. Females hunt cicadas, paralyzing them with a sting and dragging them underground to feed their larvae. Despite their intimidating size, cicada killers are not aggressive toward people. Males will buzz around perceived intruders but lack stingers entirely.
Why Both Bees and Wasps Matter
Bees are Pennsylvania’s primary pollinators, essential for the state’s apple orchards, blueberry farms, vegetable gardens, and wildflower meadows. But wasps play a role that often goes unrecognized. During their larval stage, wasps are carnivorous, and adult females hunt caterpillars, aphids, beetle grubs, and other pest insects to feed their young. Without wasps, populations of leaf-eating and seed-eating insects would go largely unchecked. The tomato hornworm, a common garden pest, is heavily controlled by parasitic wasps that lay eggs directly inside the caterpillar.
Adult wasps shift to a mostly sugar-based diet, feeding on nectar and ripe fruit. As they visit flowers, they transfer pollen. Their smooth bodies aren’t as efficient at this as fuzzy bees, but wasps still account for roughly 15% of flower-visiting insects. Some species of tiny parasitic wasps are so effective at pest control that commercial greenhouse growers release them as a pesticide-free alternative for managing aphids and whiteflies.
What About Northern Giant Hornets?
Northern giant hornets (formerly called “Asian giant hornets” or “murder hornets”) do not occur in Pennsylvania. They were briefly detected in Washington state and on Vancouver Island in Canada, but no additional workers or nests were found between 2022 and 2024, and the species has been declared eradicated from North America. If you see a large hornet in Pennsylvania, it’s almost certainly a European hornet or a cicada killer.
Managing Nests Near Your Home
If bees or wasps have nested near your house but aren’t in a high-traffic area and aren’t damaging the structure, leaving them alone is a reasonable choice. Most social wasp colonies die off naturally after the first frost, so the problem resolves itself by late fall. Honey bee swarms typically depart within two days.
When a nest does pose a genuine risk, particularly near doorways, play areas, or in wall voids, choosing the right removal method depends on the species. A yellowjacket nest underground requires a very different approach than a paper wasp nest under an eave or a carpenter bee tunnel in a deck board. After any nest is removed, repairing or sealing the area helps prevent future nesting in the same spot. For large colonies of yellowjackets, bald-faced hornets, or honey bees established inside walls, professional removal is the safest route.