Halictidae Bee Family – Guide With Pictures

Halictidae Bee

The Halictidae family is a diverse bee classification comprising almost 4,500 species distributed globally. They are the second largest family of bees and are commonly called sweat bees.

Halictids come in many shapes and sizes, although many are slender and dull or metallic black. A small number of species have metallic blue or green bodies. Male halicdids have no hairs on their hind tibia and are slimmer than females.

  • Most of the female bees collect pollen on their hind legs. A smaller number of genera are kleptoparasites, parasitic insects living off food sources from other species.
  • Halicdids are classified by their finger-like, hairless lacinia located further up the maxillary tube than other bee families. They have short tongues and typically have a strongly curved basal vein, and females have a narrow pseudopygidial area.
  • Members of the Halictidae Bee Family typically nest underground. They burrow into soft, rotting wood, river banks, or clay.
A goup of Halictidae bees resting on a branch
Several bees from the Halictidae family.

One of the fascinating aspects of Halictidae is their varying degrees of social behavior. The family exhibits a broad spectrum of social structures, ranging from solitary nesting to complex eusociality, similar to honey bees, where a single queen lives with many workers.

DistributionAll continents except Antarctica
Number of speciesAlmost 4,500
SubfamiliesHalictinae, Raphitinae, Nominae, Nomioidinae

Some species also display communal living, where multiple females share a nest, but each cares for her own offspring.

Halictidae bees play an essential role in pollination. Despite their small size, they contribute to pollinating a variety of plants, including crops, thus playing a vital role in maintaining biodiversity and agricultural production.

Tip: We summarize all seven bee families here.

Halictidae subfamilies

The Halictidae family comprises the Halictinae, Rophitinae, Nomiinae, and Nomioidinae subfamilies.

1. Halictinae

The Halictinae are the largest subfamily within the Halictidae, comprising over 3,500 species in 50 genera. They are found on every continent except Antarctica.

Most male and female halicdids have a strongly curved basal vein and a narrow pseudopygidial area.  

They exhibit various social structures, from solitary nesting to communal and eusocial living.

The cells within Halictinae nests are often lined with a waxy substance. Researchers believe it is produced by the bee’s Dufour’s gland, located in its abdomen.

Notable genera

Augochlora: also known as the green sweat bee, the Augochlora is a visually striking bee known for its bright, metallic green or purple coloration. Located in North, Central, and South America, they are solitary insects that often nest in rotting wood.

Closeip of a metallic green Augochlora pura
Augochlora pura.

Augochlorella: small bees found in the Americas, this genus is primarily social. Their nests are underground with a queen and several workers helping with work.

Macro shot of a Augochlorella aurata pollinating a purple aster bloom.
Augochlorella aurata pollinating a wild aster.

Megalopta: known as the “nocturnal bee,” Megalopta is a fascinating genus native to tropical regions. Unlike most bee species, some Megalopta can fly at night, demonstrating an adaptation to forage under low-light conditions. They are mostly pale in color and nest in hollowed-out twigs.

Agapostemon: are primarily found in the Americas and have metallic green or blue coloration. Their metasoma is banded yellow and black, similar to a yellowtail wasp.

A Agapostemon virescens on a flower
Agapostemon virescens.

Caenohalictus: a genus that is widely varied in appearance; many are metallic green, purple, or blue with red highlights. Found in Central and South America, these bees usually have exceptionally hairy eyes to check the wind direction.

Halictus: a widely distributed genus found in most parts of the world, these bees are mostly black or greenish. They enjoy temperate climates and often live in eusocial nests.

Halictus maculatus zoomed in photograph showing the insect's anatomy in detail
Halictus maculatus.

Lasioglossum: the largest genus of almost 1900 species, with a wide global distribution. Species in this genus exhibit a broad range of social behaviors, from solitary to eusocial. Some Lasioglossum species are particularly cold-tolerant and may live in Arctic regions. Most bees in this family are small with black, brown, or dull metallic bodies.

A Lasioglossum calceatum on white flowers
Lasioglossum calceatum.

Sphecodes: a genus made up of almost 300 species of cleptoparasitic or “cuckoo bees.” They lay eggs in the nests of other bees, and their larvae consume the host’s pollen stores. They have a distinctive, almost wasp-like appearance, often reddish or black. These bees lack the dense body hair seen in most others.

2. Rophitinae

The Rophitinae have antennae close to their face. There are over 250 species that typically have specific floral preferences.

Notable genera

Dufourea: comprising 170 species, the Dufourea are oligolectic, specializing in one pollen source. They are dark brown to black, although a few have bright metallic bodies. Dufourea live in the northern hemisphere but won’t tolerate cold climates. 

Systropha: are known for collecting pollen all over their body surfaces. They specialize in collecting pollen exclusively from Convolvulaceae. Their heads look small relative to the rest of their body.

Systropha planidens on a white flower
Systropha planidens.

Xeralictus: a group of just two large bees that inhabit the arid regions of the southwestern United States and Mexico. These bees are adapted to desert life and only feed from plants in the family Loasaceae.

3. Nomiinae

The Nomiinae subfamily lives on all continents except South America and Antarctica. There are 600 species in this subfamily; they often build nests with vertical cells in clusters.

Notable genera

Nomia: also known as striped sweat bees, are found worldwide and are particularly well-known for their distinctive, bright, metallic blue or green coloration and abdominal striping. Many species exhibit communal nesting, where multiple females share a nest, but each cares for her own offspring.

Nomia on a branch with a green background
Closeup of a nomia bee.

Dieunomia: a small genus of medium-sized bees with red markings or large black bees. They specialize in pollen collection from the Asteraceae.

Lipotriches: a diverse genus of bees, particularly abundant in the Australasian and Indomalayan regions. One of their notable characteristics is their hind leg morphology, specifically the modification of the tibia and basitarsus into a broad, flattened surface for carrying pollen.

Pseudapis: a small genus of bees found in southern Europe and Africa. There are 50 species in the Pseudapis subfamily, living in diverse habitats, from tropical rainforest to semi-arid land.

A Pseudapis diversipes on the ground
Pseudapis diversipes.

4. Nomioidinae

The Nomioidinae subfamily is a group of fewer than 100 species in three genera. These small bees are metallic in color with pale markings.

Notable genera

Nomioides: a genus of metallic and yellow bees with tiny bodies. They may nest in the vacated brood cells of larger bees. They are communal bees that live in dry regions with sandy soil.

Nomioides facilis macro photograph
Nomioides facilis.

Commonly asked questions

Why are they called sweat bees?

Sweat bees get their name from their attraction to the salt in human perspiration. They often land on people to lick off sweat but rarely sting.

Are Halictidae bees dangerous?

Halictidae bees are generally not dangerous. While they can sting, they are usually non-aggressive and only do so when threatened.

Where do Halictidae bees live?

Most Halictidae bees are ground-nesters, digging nests in bare or sparsely vegetated soil. They can be found in a variety of habitats worldwide.

Are Halictidae bees social or solitary?

It depends on the species. Some Halictidae bees are solitary, while others form social colonies. Some species can switch between being social and solitary, depending on environmental conditions.

Did you know? Halictidae fossils were discovered in amber, estimated between 96 and 75 million years old!

Interesting Halictidae research

We’ve summarized some interesting research related to the Halictidae bee family.

Danforth, B.N., Eardley, C., Packer, L. et al. Phylogeny of Halictidae with an emphasis on endemic African Halictinae. Apidologie 39, 86–101 (2008).

This paper looks at the family tree, fossil history, geographic distribution, and social behavior of a group of bees called Halictidae.

The authors use data from three genes to analyze the family tree of Halictinae, a sub-group of these bees. They include 89 species and 34 groups from all four sub-families of Halictidae in their study.

Their research offers fresh insights into the family tree of African Halictinae bees:

  • They find a close link between a small North/Central American bee group (Mexalictus) and an African/Asian group (Patellapis).
  • They suggest that a parasite bee group, Parathrincostoma, is a sub-group of its host bee group, Thrinchostoma.
  • Their data strongly supports the idea that Patellapis is a unified group. It sets up a solid framework to understand other African sub-groups, which can be used in future studies of their classifications.

Read the research>

Sarah Pahlke and others, The Loss of Sociality Is Accompanied by Reduced Neural Investment in Mushroom Body Volume in the Sweat Bee Augochlora Pura (Hymenoptera: Halictidae), Annals of the Entomological Society of America, Volume 114, Issue 5, September 2021, Pages 637–642.

This study explores how social behavior in bees affects their brain development. Two theories are tested: the social brain hypothesis (social behavior leads to more brain development) and the distributed cognition hypothesis (social behavior leads to less brain development).

Two types of bees are used for the study: Augochlorella aurata, which are social bees, and Augochlora pura, which are not social. Researchers focus on a part of the brain called the mushroom body calyces, which is crucial for learning and memory.

Both types of bees are studied at a stage in their lives when they are solitary, meaning brain development shouldn’t be influenced by interactions with others.

Findings reveal that when bees lose their social behavior, there’s a decrease in development in the mushroom body calyces part of their brains. This aligns with the social brain hypothesis.

Interestingly, the size of the bees’ ovaries doesn’t seem to relate to the size of the mushroom body calyces. This is the first study to show how losing social behaviors can affect how brains develop in different areas.

Read the research>

Wood TJ, Le Divelec R. Cryptic Diversity Revealed in A Revision of West Palaearctic Nomiapis and Systropha (Hymenoptera: Halictidae). Diversity. 2022; 14(11):920.

This research discusses how studying bees from the Old World Mediterranean region is difficult due to the need for both physical specimen samples (type material) and genetic data. However, researchers have made progress in understanding the diversity within two broad groups of bees: Nomiapis bispinosa and Systropha planidens, by discovering crucial physical samples and generating new DNA barcodes.

They found that what was once considered a single bee species, Nomiapis bispinosa is three distinct species: Nomiapis bispinosa from Morocco, Iberia to Central Asia, Nomiapis rufiventris from Morocco to Egypt (including Sicily), and a new species called Nomiapis paulyi from Portugal and Spain.

Similarly, Systropha planidens also breaks down into three separate species: S. planidens from Central Europe to Iran and European Russia, S. grandimargo from Portugal, Spain, and France, and S. anatolica from Turkey, Syria, and northern Israel.

The research also involves clarifying or reassigning the status of several bee species based on newly discovered physical samples and DNA information. All this underlines how our knowledge of Mediterranean bees is still developing.

Read the research>

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