Megachilidae Bee Family: Get The Essential Facts

A bee from the Megachilidae family on a stick with blurred background

The Megachilidae family is highly diverse, with over 4,000 species spread across the globe. They make up almost 20% of all named species of bees and include mason bees, carder bees, leafcutter bees, and resin bees.

Most bees in the Megachilidae family collect pollen using a scopa underneath their abdomen rather than on their hind legs. They have an elongated labrum that is widest at its base and a long-tongued bee morphology.

DistributionEvery continent except Antarctica
Number of speciesOver 4,000
SubfamiliesMegachilinae, Fideliinae, Pararhophitinae, and Lithurginae

Tip: We discuss all seven bee families here.

A closeup photograph of the Megachile centuncularis (Patchwork leafcutter) showing its anatomy
Patchwork leafcutter bee.

Megachilids are solitary bees native to their environment, although some have been introduced. They use a wide range of materials to build nests in above-ground cavities. Soil, leaves, plant resin, hollow stems, and old wasp nests are all potential building materials.

Most species in the Megachilidae family collect pollen and nectar. However, the exceptions are cuckoo bees (kleptoparasites), that have no scopae. Instead, they feed on food sources collected by other bees.

Closeup shot of a Trachusa byssina leaving its burrow in the ground
Byssal resin leafcutter (Trachusa byssina).

Megachilids can be found in a wide range of environments, from deserts to rainforests, demonstrating their adaptability and resilience.

They play an essential role in pollination, with alfalfa leafcutter bees used to pollinate alfalfa crops; blue orchard bees are extensively used in orchard pollination. Their vigorous movements on the flower release more pollen than most other bee species.

The family is subdivided into four subfamilies: Megachilinae, Fideliinae, Pararhophitinae, and Lithurginae. Each has unique characteristics and behaviors.

Megachilidae subfamilies

1. Megachilinae

The Megachilinae is the largest subfamily within the Megachilidae family. It comprises over 4,000 species, including the Alfalfa leafcutter bee (Megachile rotundata) and Mason bee (orchard bees).

These bees are characterized by two submarginal cells, no pygidial plate, and at least two subapical teeth on the mandible.

Closeup of a wool carder bee
The wool carder bee.

This group includes the most economically important solitary bees due to their effectiveness in pollinating crops.

Megachilids display a broad range of nesting behaviors. Some species construct nests in hollow sticks or cavities while others bore into wood or soil.

Notable genera

Anthidiellum: this genus includes 63 species, typically small, fat bees. They often construct nests on rocks and plants using resin. They are found in most parts of the world and thrive in cold or tropical climates.

Anthidium: recognizable by their robust bodies, the wool-carder bees within this genus are known for their behavior of scraping hairs from plants to construct luxurious nests. Male wood carder bees are known to be aggressive in defending their territory.

Coelioxys: known as sharp-tailed bees, Coelioxys species are cleptoparasites. They utilize their sharply pointed abdomens to pierce the cell walls of host bees’ nests to lay their eggs. Most species have unusual hair on their compound eyes.

Zoomed in image of a Coelioxys on a flower
Coelioxys bees have sharp abdomens.

Dioxys: members of the Dioxys genus are kleptoparasites. They lay their eggs in the nests of other megachilid bees and rely on their hosts to rear offspring. Their bodies have strong ridges that deflect attacks, but their stingers are smaller than stingless honey bees.

Gronoceras: found in sub-Saharan Africa, Gronoceras bees are large insects with expanded antennae that appear hollowed out. They have a vibrant black and red color pattern with patches of gray hairs.

Heriades: nest in pre-existing holes in wood or cement, sealing their nest cells with a mix of resin and small wood fragments. They are primarily small bees that can live in diverse habitats, from rainforests to desert landscapes.

Closeup of a black Heriades crenulatus bee
The Heriades crenulatus bee.

Hoplitis: the Hoplitis genus includes mason bees, named after their habit of using mud or other masonry products to construct their nests. They are mostly dark black in appearance, although some species in North America have bright metallic colors.

Hoplitis cristatula - Mason bee
Hoplitis cristatula – Mason bee.

Megachile: perhaps the most well-known of all megachilid genera, Megachile bees include the famous leafcutter bees. They use pieces of leaves or resin to create intricate nest structures. The Megachile rotundata is an essential alfalfa pollinator.

Ochreriades: found in Namibia and the Middle East, this subfamily has only two species. They are thin bees that live in wood burrows previously excavated.  

Osmia: a genus with diverse nesting behavior, these bees are renowned for pollinating fruit crops efficiently. They often nest in small cavities, constructing partitions between their eggs using masticated plant material.

Red mason bee closeup picture
Red mason bee.

Rhodanthidium: is a central Asia and Mediterranean genus of bees that commonly nests in snail shells. Their bodies have red or yellow markings, and they live in areas with large populations of snails.

Trachusa: these bees build nests underground, lining their brood cells with resin and plant material. Their appearance varies greatly, with some looking similar to bumble bees.

Serapista: generally colored black with patches of white fur, they look similar to a beetle. These bees create ball-shaped nests out of plant fiber, hair, and feathers.

A Serapista bee on a purple bloom
The Serapista bee looks like a beetle.

2. Fideliinae

The Fideliinae is a smaller subfamily with 19 ground-nesting bee species. They are found in southern Africa, Peru, Morocco, and Chile. These are the only megachilids with three submarginal cells, rather than the standard two.

Notable genera

Neofidelia: a relatively rare bee genus in the southern African region. Their distinct characteristics and unique ground-nesting behaviors. They contribute to the biodiversity of the local ecosystems, playing crucial roles in plant pollination.

Xenofidelia: an intriguing genus with species distributed in the arid regions of Peru and Chile. Though relatively understudied, these bees are notable for their resilience in challenging environments and their potential role in desert flora pollination.

3. Pararhophitinae

The Pararhophitinae contains a single genus, Pararhophites, It is composed of three small species found in arid environments from Morocco to northwestern India. These bees construct shallow nests in the ground and have extensive pale markings on the integument. The females have no subapical teeth.

Notable genus

Pararhophites: this small subfamily is found in dry parts of northwest India and Morocco. Unlike most other members of the Megachilidae family, foragers collect pollen over their whole body. Females are pale, while males are darker, with pale marks.

4. Lithurginae

The Lithurginae includes 64 species in five genera identified by their absence of pale markings. They also have pygidial plates and two submarginal cells. These bees are found on all continents except Antarctica and thrive on many islands.

Notable genera

Lithurgus: is distributed worldwide and can survive in habitats as diverse as rainforests and hot tropical islands. The Lithurgus chrysurus can chew through hard wood like structural beams, making it a pest on some countries.

Trichothurgus: this genus of 14 species contains mostly large bees with long pretarsi. Most of these bees are specialists, focusing on one type of plant. They live in South America, from southern Argentina to Peru.

Macro of a Mediterranean wood-boring bee
Mediterranean wood-boring bee.

10 fun facts about Megachilids

  1. The Megachilidae family comprises mason bees, leafcutter bees, and resin bees.
  2. They use materials like leaves, mud, and resin to construct their nests, displaying incredible ingenuity.
  3. The largest bee in the world is the Megachile pluto, or Wallace’s giant bee. It was thought to be extinct until 1981 when it was found in Indonesia.
  4. Unlike most bees that carry pollen on their hind legs, Megachilid bees have a specialized structure on the underside of their abdomen called the scopa.
  5. Megachilids are primarily solitary bees. Each female mates and then builds her own nest, unlike the communal living of honeybee and some bumblebee colonies.
  6. The family is highly diverse, with over 4,000 species spread across every continent except Antarctica. This demonstrates their ability to adapt to a wide range of environments.
  7. Some Megachilid bees, like those in the genera Coelioxys and Dioxys, are kleptoparasites. They lay eggs in the nests of other bees and let the host bees rear their offspring.
  8. Megachilidae family members are renowned for their pollination efficiency. In some cases, a single female can do the work of several honeybees.
  9. The best known members of the family are the leafcutter bees. They cut neat circles from leaves or petals, used to line nest cavities.
  10. Alfalfa leafcutter bees are used in agriculture for their pollination skills. They are vital for pollinating crops like alfalfa and play an essential role in our food supply chain.
Anthidiellum strigatum closeup
A European rotund resin bee.

Commonly asked questions

What are Megachilidae bees?

Megachilidae bees are a large family of bees known for their unique behavior of carrying pollen on their abdomens rather than using their hind legs. They are essential pollinators and include leafcutter, mason, and carder bees.

How do Megachilidae bees build their nests?

Megachilidae bees are generally solitary bees, with each female constructing her own nest. They often use plant material, such as leaves or petals, and in some cases, mud or resin, to build their nests.

Where can I find Megachilidae bees?

Megachilidae bees have a worldwide distribution and can be found in preactically any habitat, from forests and deserts to urban gardens.

Zoomed up shot of a Rhodanthidium sticticum - Spotted red resin bee
Rhodanthidium sticticum – Spotted red resin bee.

What plants do Megachilidae bees pollinate?

Megachilidae bees visit a wide variety of flowering plants. Some species are generalists that visit many types of plants, while others are specialists adapted to a smaller number of plant species. They are effective pollinators for fruit trees and wildflowers.

What are the threats to Megachilidae bees?

Megachilidae bees face many of the same threats as other bees, including habitat loss, pesticide exposure, disease, and climate change. Changes in flowering plant availability due to human activities can also impact their populations.

How can I help conserve Megachilidae bees?

Planting native flowering plants, reducing pesticide use, providing nesting sites (like bee hotels), and supporting conservation efforts can all help to protect Megachilidae bees.

Are Megachilidae bees aggressive?

Megachilidae bees are generally not aggressive and are unlikely to sting unless threatened. They are safe and beneficial to encourage in the back yard.

Interesting Megachilidae research

Grace M Gutierrez and others, Osmia taurus (Hymenoptera: Megachilidae): A Non-native Bee Species With Invasiveness Potential in North America, Environmental Entomology, Volume 52, Issue 2, April 2023, Pages 149–156.

Bees, while crucial for plant reproduction, can harm ecosystems when introduced outside their native regions. Numerous non-native bee species, now present in North America, may be contributing to the decline of native bee populations.

One species, the mason bee (Osmia taurus), is native to eastern Asia. It was first reported in the US in 2002 and has since spread rapidly across eastern North America.

The researchers review the natural history and spread of O. taurus. They discuss invasive potential and compare its colonization history to another non-native mason bee, O. cornifrons.

The paper calls for further research to understand the role of O. taurus in the decline of native Osmia species. It also looks at the possible role in supporting invasive plant-pollinator relationships.

Read more>

Felicioli A, Sagona S, Coppola F, Boni CB, Pinzauti M. Effect of Ageing in the Mating Behaviour Sequence of Osmia cornuta Latr. (Hymenoptera: Megachilidae). Insects. 2023; 14(4):335.

Osmia cornuta Latr. is a bee species commonly used worldwide for pollinating orchard crops, supporting ecosystems, and providing economic and social benefits.

Its emergence from cocoons can be delayed, which helps pollinate late-blooming crops.

This study examines the mating behaviors of bees that emerge naturally and those whose emergence is delayed to see if it impacts the mating process.

Both groups of bees display repeated, stereotyped behaviors, including antenna motion, pouncing, sound emission, abdomen stretching, copulation, scratching, inactivity, and self-grooming.

The frequency of short copulations, which can result in failed reproduction, increased with the age of the bees.

Read more>

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