9 Types of Sweat Bees You Can Find in Gardens and Fields

A tiny metallic-green insect landing on your arm mid-hike is usually not hunting your snack — it wants the salt in your sweat. That habit gives sweat bees their name, and scientists recognize many types of sweat bees spread across four subfamilies and dozens of genera worldwide. The family behind these insects, Halictidae, is the second-largest family of bees with nearly 4,500 species.

This rundown covers nine of these groups: the four subfamilies that make up Halictidae, four genera of iridescent green bees that gardeners frequently spot on flowers, and one ground-nesting species that has become one of agriculture’s most valuable pollinators. Each entry looks at size, color, nesting habits, and the small anatomical details that separate one group from the next.

1. Halictinae

Halictinae holds the bulk of the diversity that most people picture when they hear “sweat bee.” Halictinae is the largest subfamily, with over 3,500 species, and most are characterized by a strongly curved basal vein in their wings. Many species flash metallic green, though a large share are simply black or brown with pale hair bands.

Nesting habits vary as much as appearance does. Halictinae have diverse nest types, including series of cells, scattered cells, and clusters of cells, and researchers in Florida have documented eight genera within the subfamilies Nomiinae and Halictinae, including Sphecodes, Lasioglossum, Nomia, Agapostemon, Augochloropsis, Augochlora, Augochlorella, and Halictus.

1. Species count: The largest of the four subfamilies, outnumbering the other three combined.
2. Wing structure: A distinctly curved basal vein separates this group from other bee families entirely.
3. Nesting style: Ranges from simple scattered cells to dense clusters, depending on species.
4. Representative genera: Includes Halictus, Lasioglossum, Agapostemon, and the Augochlorini genera covered below.

Pro Tip: Sweat bees are often mistaken for cuckoo wasps or hover flies. Watch flight behavior — sweat bees fly more directly to flowers, while hover flies hover in place and cuckoo wasps have a pitted, sculptured body texture.

2. Nomiinae

Nomiinae is smaller than Halictinae but still substantial. There are about 11 genera and at least 550 described species in Nomiinae, and members are sometimes called striped sweat bees because many of these are characterized by blue-green metallic bodies and striped abdomens.

Nesting behavior sets this group apart from its relatives as well. Nomiinae build vertical cells, sometimes in clusters, a pattern that differs from the more varied nesting seen in Halictinae. The genus Nomia, discussed later in this list through its best-known species, belongs to this subfamily.

1. Species count: Roughly 550 or more described species across about 11 genera.
2. Coloration: Blue-green metallic bodies paired with striped abdominal bands.
3. Nesting style: Vertical cells, sometimes grouped into clusters underground.
4. Notable genus: Nomia, home to one of the world’s most economically important solitary bees.

3. Rophitinae

Rophitinae is a smaller, less conspicuous subfamily. There are about 13 genera and more than 260 described species in Rophitinae, and the group is best identified by facial structure rather than color: Rophitinae are characterized by antennae close to their faces.

Foraging behavior is where Rophitinae stands out most. While many sweat bees are generalist foragers, many Rophitinae species have specific floral preferences, specializing in only a few pollen sources. Underground, larval cells typically are excavated either at a slant or horizontally off of a main lateral tunnel.

1. Species count: More than 260 species spread across roughly 13 genera.
2. Identifying trait: Antennae positioned unusually close to the face.
3. Foraging behavior: Many species are floral specialists rather than generalists.
4. Nesting style: Slanted or horizontal cells branching off a main tunnel.

4. Nomioidinae

Nomioidinae is the smallest of the four subfamilies. Nomioidinae includes three genera and more than 80 species, and they are small, with most less than 5 mm long, often showing metallic blue or green colours and prominent pale markings.

Geography and nesting habits reflect this group’s preference for dry, open ground. Most species are found in arid and semi-arid regions of Africa, Central Asia, and Southern Asia, with one species found in Australia, and they typically nest in the ground, favoring sandy or rocky soils and often forming small to large nesting aggregations. Each species is also polylectic, collecting pollen from a range of unrelated plants rather than specializing.

1. Species count: More than 80 species across just three genera — the smallest subfamily by far.
2. Size: Most individuals measure under 5 mm, among the smallest bees in the family.
3. Range: Concentrated in arid regions of Africa, Central Asia, and Southern Asia.
4. Nesting style: Ground-nesting in sandy or rocky soil, often in aggregations.

4..1 Halictidae Subfamilies Compared

Subfamily	Approximate Species Count	Key Identifying Feature
Halictinae	Over 3,500	Strongly curved basal wing vein
Nomiinae	At least 550	Blue-green metallic, striped abdomens
Rophitinae	More than 260	Antennae close to the face
Nomioidinae	More than 80	Tiny size, under 5 mm

5. Agapostemon

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Agapostemon is one of the easiest sweat bee genera to spot in a flower bed. Agapostemon virescens and its relatives are a group of stocky, metallic green bees, and males can be recognized instantly because Agapostemon males can be recognized instantly by their unique combination of a metallic green head and thorax and black and yellow striped abdomen.

Females look different depending on species. Of the six species that occur in Minnesota, all females have a green abdomen except for Agapostemon virescens, which has a black abdomen with white stripes. Compared to its metallic green relatives, Agapostemon are larger and more robustly built than the other metallic green bees, always have non-metallic tegulae, and often have vague bands of fuzzy pale hairs on their abdomen.

Nesting is straightforward for this genus. Bees in this genus nest in the ground in either a solitary or communal nest, and they are medium-sized, ranging in length from 7 to 18 mm.

1. Size: 7 to 18 mm, larger and stockier than related green genera.
2. Male appearance: Metallic green head and thorax with a black-and-yellow striped abdomen.
3. Female appearance: Solid green abdomen in most species; black-and-white striped in Agapostemon virescens.
4. Nesting: Ground-nesting, either alone or in loose communal groups.

6. Augochlora

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Augochlora belongs to the tribe Augochlorini, a group of predominantly Central and South American bees with a handful of representatives further north. Augochlora, Augochloropsis and Augochlorella sweat bees belong to the tribe Augochlorini, and bees in this tribe are brilliantly colored, usually ranging from golden-green to an intense pure green to a dazzling blue-green. Some, including Augochlora pura, add copper or pink tones to that palette.

Size is one of the more reliable ways to tell this genus apart from its lookalikes. In the eastern United States, Augochlora are usually about 8 mm long, while Augochlorella typically range between 5.5 and 7 mm. Nesting habits also differ from many other sweat bees, since Augochlorini tend to build nests in soil or, less commonly, in rotted wood.

1. Classification: Member of the tribe Augochlorini, largely a Central and South American group.
2. Coloration: Golden-green to blue-green, sometimes copper or pink-tinged.
3. Size: About 8 mm in the eastern United States, larger than Augochlorella.
4. Nesting: Typically in soil, occasionally in rotted wood.

Common Mistake: Augochlora, Augochlorella, and Augochloropsis are frequently confused with each other and with Agapostemon because all four genera share the same iridescent green coloring. Leg color, tegulae, and body size are more reliable clues than overall hue.

7. Augochloropsis

Augochloropsis is the genus most often mixed up with Agapostemon. Augochloropsis are also often misidentified as Agapostemon, a genus of large green striped sweat bees, though a closer look at the legs settles the question: male Augochloropsis have legs that are iridescent green from the top segment through the tibia, with white basitarsi on all legs.

A different feature separates Augochloropsis from its closer relative Augochlorella. The hind tibial spur is simple or slightly serrated in Augochlorella, distinguishing it from the genus Augochloropsis, which has a more strongly toothed spur. In the Lower Rio Grande Valley, Augochloropsis tend to run larger than bees of the other two genera in the tribe.

1. Lookalike risk: Frequently confused with Agapostemon due to similar green coloring and size.
2. Leg color: Iridescent green legs with distinctive white basitarsi in males.
3. Distinguishing feature: A more strongly serrated hind tibial spur than Augochlorella.
4. Size: Generally the largest-bodied of the three Augochlorini genera in many regions.

8. Augochlorella

Augochlorella is the smallest and, in many areas, the most commonly encountered of the green Augochlorini genera. Its best-studied member, Augochlorella aurata, is a primitively eusocial species of sweat bee in the family Halictidae, meaning some colonies have both a reproductive queen and worker-like females in the same nest.

Color helps identify this species at a glance. The body is a brilliant green metallic color, diffused to varying extents with a copper, red, or yellow color. Structurally, the propodeum is relatively uniform, with no ridge, separating it from bees in the closely related genus Agapostemon, which makes leg and thorax details more useful than color alone for identification.

Genus	Typical Size	Distinguishing Feature
Agapostemon	7–18 mm	Non-metallic tegulae, larger build
Augochlora	About 8 mm	Nests in soil or rotted wood
Augochloropsis	Largest of the three Augochlorini genera	Iridescent green legs, white basitarsi
Augochlorella	5.5–7 mm	Uniform propodeum, no ridge

1. Notable species: Augochlorella aurata, one of the few primitively eusocial sweat bees studied in North America.
2. Coloration: Brilliant metallic green often diffused with copper, red, or yellow.
3. Size: The smallest of the three Augochlorini genera in the eastern United States.
4. Distinguishing trait: A smooth, ridge-free propodeum sets it apart from Agapostemon.

9. Nomia melanderi (alkali bee)

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The alkali bee is the single species on this list, and it earns its place through sheer agricultural value. Formally named Nomia melanderi, it is a ground-nesting bee native to deserts and semi-arid desert basins of the western United States, described by Theodore Dru Alison Cockerell in 1906. As its name suggests, this bee nests in salt-saturated, or alkaline, soil.

Unlike many solitary bees, alkali bees are highly social in their nesting arrangements. While solitary, these bees nest near each other and can form extremely dense aggregations in areas with favorable conditions. That gregarious nesting habit, combined with strong pollination activity, has made the species one of the more intensively studied halictids: some species, including the alkali bee, Lasioglossum vierecki, and L. leucozonium, are important crop pollinators.

Researchers also value the alkali bee for what it reveals about bee evolution. The subfamily is the sister clade to the Halictinae, which includes both solitary and social lineages, and alkali bees may be representative of the solitary ancestor from which eusociality likely evolved within the bee family Halictidae. That combination of practical importance and evolutionary insight keeps the species central to ongoing research.

1. Classification: Genus Nomia, subgenus Acunomia, within the subfamily Nomiinae.
2. Habitat: Desert and semi-arid basins with salt-saturated or alkaline soil.
3. Nesting behavior: Solitary nests built in extremely dense aggregations.
4. Ecological importance: A key managed pollinator and a model species for studying the origins of eusociality.

Key Insight: Because alkali bees nest so densely in alkaline soil, growers in parts of the western United States actively manage artificial “bee beds” to encourage populations near alfalfa seed fields, turning a wild ground-nester into a semi-domesticated pollination workforce.

From the wing-vein details that define Halictinae to the salt-loving nesting habits of the alkali bee, these nine groups show how much variation hides inside a single family of small, often-overlooked pollinators. Most are harmless to encounter and land on skin only briefly in search of moisture and salt. Recognizing subfamily traits, genus-level color patterns, and nesting behavior makes it far easier to tell one type of sweat bee from another the next time one lands nearby.