19 Types of Wasps in Montana: A Field Guide to Every Species
November 8, 2026
Montana is home to far more wasps than the yellowjackets that crash summer barbecues. Anyone researching types of wasps in Montana quickly discovers a hidden world of solitary hunters, parasitic egg-layers, and metallic gem-colored insects that most residents never notice. According to entomologist Mike Ivie of the Montana Entomological Collection in Bozeman, the state hosts at least 71 species of cuckoo wasps alone, a number that rivals the state’s entire list of native mammals.
This guide walks through 19 wasp species found across Montana, covering the aggressive scavengers that raid picnics, the docile solitary hunters that never bother people, and the strange in-between species that parasitize other insects. Whether the goal is wasp identification in Montana backyards or simply satisfying curiosity about a paper nest under the eaves, each section below covers appearance, nesting habits, and behavior. For readers comparing notes with neighboring states, Montana’s wasp community overlaps heavily with the broader wasps found across North America.
1. Western Yellowjacket
The western yellowjacket (Vespula pensylvanica) is the wasp most Montanans think of when they hear the word “yellowjacket.” Montana State University Extension identifies it as the biggest nuisance pest around backyards and porches in late summer, and notes that although other wasps and bees can sting, most stings in the state come from this one species.
Colonies build nests that are often underground or tucked into wall voids, which makes them easy to step on or disturb without warning. This species is a scavenger that feeds on garbage, sugary drinks, and dead insects, a habit that draws it toward grills, trash cans, and picnic tables during August and September. Wasp populations in general reach their highest point of the year in late summer across Billings, Bozeman, and Missoula as colonies hit maximum size before the season ends.
Pro Tip: Yellowjacket traps work best when placed outdoors in spring, before colonies grow large and while queens are still emerging. Traps sold for western yellowjackets generally will not catch other Montana wasp or bee species.
2. German Yellowjacket
The German yellowjacket (Vespula germanica) is not native to North America. It belongs to the genus Vespula, a group of social wasps found throughout the Northern Hemisphere, and arrived in the Americas through accidental introduction before spreading widely.
Workers grow to roughly 13 millimeters and carry the classic black-and-yellow banding, though they can be told apart from close relatives by three small black dots on the face. This species is an opportunistic generalist, eating live spiders, other insects, fruit, and even dung when the opportunity arises. That flexible diet, paired with a willingness to nest close to homes, makes it one of the more commonly reported wasps in states as far north as Montana and Minnesota.
3. Alaska Yellowjacket
The Alaska yellowjacket sits in the same genus as the western and German yellowjackets and shares their general black-and-yellow banding, stout body shape, and paper nest construction. It was long treated as part of the common yellowjacket group before researchers split it into its own recognized species within North American populations.
In Montana, this species tends to turn up in cooler, higher-elevation habitats rather than the lowland yards where western yellowjackets dominate. Because the visual differences between yellowjacket species are subtle, most homeowners rely on nest location and elevation as practical clues rather than trying to count facial markings in the field. Readers comparing regional wasp lists may notice similar overlap with colder-climate states such as Nebraska, where several of the same Vespula species also appear.
4. Common Aerial Yellowjacket
The common aerial yellowjacket (Dolichovespula arenaria) goes by several regional nicknames, including the Sandhills hornet. It is black with yellow markings and smoky, clear wings, with a stout body slightly wider than its head, and it adapts readily to a range of Montana habitats from forest edges to suburban yards.
Unlike the western yellowjacket’s underground nests, this species usually builds its papery nest in trees and shrubs, though it will occasionally attach one to the side of a house. It defends its colony aggressively and can sting repeatedly, and it has an unusual extra defense: the ability to spray venom at attackers rather than only delivering it through a sting. That combination of an aerial nest and airborne venom makes it worth identifying correctly before attempting removal, a caution that also applies to aerial-nesting wasps reported in Alabama.
5. Bald-faced Hornet
Despite the common name, the bald-faced hornet (Dolichovespula maculata) is not a true hornet at all. It is technically classified as an aerial yellowjacket, distinguished by its large black-and-white coloring and the oversized, football-shaped paper nests it builds in trees and on structures.
Montana State University lists it among the state’s most common social wasps, alongside the aerial yellowjacket, western yellowjacket, and paper wasps. Like most Montana social wasps, it is generally not aggressive unless its nest is disturbed, but a bald-faced hornet nest near a doorway or patio can turn a minor bump into a painful multi-sting encounter. The same genus shows up in wasp inventories from Montana all the way down to Louisiana, illustrating how widely this species has spread across the country.
| Species | Typical Nest Location | Temperament |
|---|---|---|
| Western Yellowjacket | Underground or wall voids | Most aggressive; frequent stings |
| German Yellowjacket | Wall voids, attics, ground | Aggressive when nest disturbed |
| Common Aerial Yellowjacket | Trees, shrubs, occasionally structures | Defensive; can spray venom |
| Bald-faced Hornet | Trees and building eaves | Calm unless nest is disturbed |
6. Western Paper Wasp
Montana’s native paper wasp population is dominated by a slender, long-legged species built for hanging umbrella-shaped nests under eaves, in garages, and around window frames. Homeowners in the state will most likely encounter two types of paper wasps, and this native species is typically the less confrontational of the pair.
Workers hunt caterpillars, aphids, and other soft-bodied pests to feed their larvae, which makes colonies a quiet benefit to backyard gardens for most of the season. Nests stay relatively small compared to yellowjacket colonies, usually topping out at a few dozen cells rather than the thousands a mature yellowjacket nest can hold. Gardeners tracking similar native paper wasp activity in the Midwest can compare notes with reports from Missouri.
7. European Paper Wasp
The European paper wasp (Polistes dominula) is the second of Montana’s two common paper wasps, and it did not originate here. Its bright yellow-and-black coloration means it is often confused with native yellowjackets, but researchers have found that this invasive species tends to outcompete native paper wasps and negatively affects caterpillars, including monarch butterflies.
European paper wasps build nests almost anywhere with a sheltered overhang, including attics, light fixtures, grills, boats, and mailboxes. They are fairly non-aggressive as long as the nest is left alone, but stings usually happen when someone accidentally brushes against a nest tucked into an overlooked corner. Because the coloring overlaps so closely with other black-and-yellow insects, several regional guides to insects that look like bees list this species as a common source of misidentification.
Important Note: The European paper wasp’s spread across Montana has measurable ecological consequences. Because it competes directly with native paper wasps and preys on monarch caterpillars, its presence near a garden is not purely a nuisance issue but part of a broader shift in local insect communities.
8. Golden Paper Wasp
The golden paper wasp (Polistes aurifer) stands out from Montana’s other paper wasps thanks to its golden-yellow body marked with reddish-brown stripes and legs. The species is native to many southern states and only reaches a handful of northern states, where it has a much shorter active season, which places Montana near the edge of its usual range.
Where it does occur, the golden paper wasp behaves much like its relatives, building open umbrella-shaped nests and hunting soft-bodied insects to feed its young. Because Montana sits at the cooler margin of this species’ distribution, sightings tend to cluster in warmer valleys and lower-elevation areas during peak summer. Its range overlaps more heavily with warmer states such as Texas, where the season lasts considerably longer.
9. Ichneumon Wasp
Ichneumon wasps belong to the family Ichneumonidae, one of the most species-rich families in the entire insect world. In Montana, they are typically black or brown with red, yellow, or white markings, and their most recognizable feature is a long, needle-like ovipositor used to inject eggs directly into a host insect such as a caterpillar or beetle.
These wasps are predators and parasitoids rather than stinging pests, meaning their larvae develop by consuming the host insect from the inside. That lifestyle makes them genuinely beneficial to gardeners and farmers, since they help keep populations of plant-eating caterpillars and beetles in check. Statewide surveys list numerous ichneumon genera present in Montana, a diversity mirrored in broader inventories of parasitic wasps found in states like Ohio.
10. Norton’s Giant Ichneumon Wasp
Norton’s giant ichneumon wasp (Megarhyssa nortoni) is one of the largest and most startling wasps a person might encounter in a Montana forest, thanks to an ovipositor that can rival or exceed the length of its own body. Despite the intimidating appearance, this species poses no sting threat to people; the long thread-like structure trailing behind the female is an egg-laying tool, not a weapon.
Females use that ovipositor to drill through tree bark and deposit eggs directly into the tunnels of wood-boring horntail larvae, which then become hosts for the developing ichneumon young. This precise, almost surgical targeting of hidden prey inside solid wood is part of what makes giant ichneumons such effective natural regulators of wood-boring insect populations, the same insects covered in guides to insects that eat wood.
11. Cuckoo Wasp
Cuckoo wasps, family Chrysididae, are among the most overlooked insects in Montana despite their striking metallic coloring. Some shine coppery red in the light, and most people walk past hundreds of them every summer without ever noticing, since these tiny wasps rarely visit picnics or show any interest in human food.
Unlike nearly every other wasp on this list, female cuckoo wasps cannot sting at all. They carry only a harmless egg-laying tube, and species such as Holopyga ventralis can roll partway into a defensive ball when threatened rather than fighting back. Cuckoo wasps earn their name from a parasitic strategy: they seek out nests already stocked with food by other solitary wasps or bees and lay their own eggs inside, letting another species’ hard work raise their young.
Key Insight: Montana’s cuckoo wasp diversity was barely documented until the 1990s, when entomologist Mike Ivie began a thorough statewide inventory. That effort revealed nearly as many cuckoo wasp species in Montana as native mammal species, a hidden layer of biodiversity most residents never suspect exists in their own backyards. Readers curious about the state’s broader insect variety can browse a wider look at different types of insects.
12. Boll’s Potter Wasp
Boll’s potter wasp (Eumenes bollii) is easy to pick out from Montana’s other potter wasps because of its distinctive red shading, which makes it the only red-shaded Eumenes species found in the state. Like other potter wasps, it has a small body with a noticeably pointed tip to the abdomen.
This solitary species builds small, jug-shaped mud pots rather than the papery hanging nests favored by yellowjackets and paper wasps, provisioning each pot with paralyzed caterpillars before sealing an egg inside. Because it hunts quietly and avoids confrontation, it almost never causes stinging problems for people working in gardens or flower beds. Similar potter wasp genera appear in wasp surveys stretching north into Canada.
13. Kennicott’s Mason Wasp
Kennicott’s mason wasp (Stenodynerus kennicottianus) is a native Montana species documented in the Montana Field Guide’s listing of the family Vespidae, though the guide itself notes that detailed information on this species remains incomplete.
That gap is common among Montana’s solitary mason and potter wasps, which receive far less research attention than the handful of social species that build noticeable nests near homes. Mason wasps in general construct small mud-sealed nest cells in existing cavities, such as old beetle burrows or hollow plant stems, rather than excavating burrows from scratch. Their understated lifestyle keeps them largely invisible to anyone not specifically looking for them, similar to many solitary wasps documented in New York insect surveys.
14. White-banded Potter Wasp
The white-banded potter wasp is a solitary member of the same subfamily as Boll’s potter wasp, recognizable by pale banding across an otherwise dark abdomen and the same pinched, pointed abdominal shape shared across the group. Like its relatives, it builds small pot-shaped mud cells rather than papery combs.
Females provision each mud cell with paralyzed caterpillars as food for a single developing larva, then seal the cell before moving on to build another. This one-larva-per-cell approach is far more labor-intensive than the shared nest-building of social wasps, but it means these wasps rarely gather in numbers large enough to threaten people. Potter wasp diversity is far higher in tropical regions, where guides to insects of the Amazon rainforest document dozens of related species.
15. Beewolf
Beewolves, genus Philanthus, are solitary, ground-nesting wasps that hunt bees to stock their underground brood cells. Despite the intimidating name, they are not aggressive toward people and rarely sting unless handled directly.
One common species, Philanthus gibbosus, grows to about 12 millimeters, with a broad head, shiny body, yellow spots on the head, and yellow stripes across the thorax and abdomen. It is frequently spotted visiting flowers while searching for bee prey to paralyze and carry back to its burrow. Because beewolves and several bat species both help keep flying insect populations in check around Montana yards, readers interested in the state’s other natural pest controllers may want to look at Montana’s bat species.
16. Weevil Wasp
Weevil wasps, genus Cerceris, are small, solitary hunters that specialize in capturing weevils and other beetles to provision their nests. They can be told apart from other small black-and-yellow wasps by a smaller, raised top section on the abdomen, a subtle feature that takes practice to spot in the field.
Like most of the small wasps that visit flower beds and garden borders, weevil wasps almost never cause stinging problems for people, since their hunting behavior is focused entirely on beetle prey rather than defending territory. They nest in burrows dug into bare or sandy soil, often in sunny, open patches of yard. Anyone curious how weevil wasps compare to Montana’s larger, more conspicuous species can browse a broader overview of different types of wasps.
17. Mud Dauber
Mud daubers are dark-colored, thread-waisted solitary wasps best known for the hard, tube-shaped mud nests they build on ceilings, walls, and eaves. They belong to the family Sphecidae, are not social wasps, and are frequently confused with more aggressive species even though they rarely sting.
The black-and-yellow mud dauber hunts spiders almost exclusively, paralyzing prey and packing it into mud cells as food for a single developing larva. Because mud daubers do not defend their nests the way yellowjackets do, an old nest left untouched under an eave is rarely a safety concern. Given how heavily this species relies on spiders as prey, anyone interested in what mud daubers are hunting locally might find it useful to check a guide to Montana’s spider species.
Pro Tip: An old, abandoned mud dauber nest does not need to be removed for safety reasons. These wasps rarely reuse cracked or damaged nests, and leaving one in place costs nothing while the species continues quietly controlling spider populations elsewhere on the property.
18. Large Pollen Wasp
The large pollen wasp (Pseudomasaris vespoides) breaks the typical wasp mold in one major way: rather than provisioning nests with paralyzed insects, it feeds its larvae a mixture of pollen and nectar, much like a bee. This unusual diet places it in the small subfamily Masarinae, a group that behaves more like specialized bees than typical hunting wasps.
Adults are often spotted visiting penstemon and other tubular flowers across Montana’s drier valleys and foothills, where their bee-like foraging can easily lead to misidentification. Because the resemblance to bees is so strong, this species frequently shows up in discussions of insects that look like bees despite being a true wasp. Pollen wasps overall are a small, specialized group compared to more widespread insect families documented in regions such as the Philippines.
19. Thread-waisted Wasp
Thread-waisted wasps, genus Ammophila, take their common name from an extremely narrow, elongated connection between the thorax and abdomen that makes them easy to distinguish from bulkier wasps at a glance. One documented Montana species, Ammophila aberti, is roughly half an inch long with a reddish-brown body marked by black patterning.
These solitary wasps dig burrows in sandy or loose soil and hunt caterpillars to provision their nests, dragging prey that can be many times their own body weight back to the burrow entrance. They are not aggressive toward people and generally go unnoticed unless someone happens to watch one dragging a paralyzed caterpillar across open ground. The genus is widespread enough that related thread-waisted species turn up in insect surveys as far away as the Philippines, underscoring how this body shape has succeeded across very different climates worldwide.
Montana’s wasp community ranges from the underground colonies of the western yellowjacket to solitary hunters like the beewolf and weevil wasp that most people will never notice. Understanding a few key traits, nest location, body shape, and behavior around disturbance, makes it far easier to tell a genuinely dangerous species from one of the many harmless solitary wasps quietly working through a Montana backyard. For anyone building out a broader picture of the state’s insect life beyond wasps, an overview of different types of insects is a useful next stop.