Megachile

Latreille, 1802

Leafcutter bees, Leafcutting bees, Resin bees, Mortar bees

Species Guides

54

Megachile is a large, of solitary bees in the Megachilidae, comprising over 1,500 described across more than 50 subgenera. The genus includes the commercially important alfalfa leafcutter (M. rotundata), managed globally for crop pollination. Species exhibit diverse nesting strategies: many cut circular leaf or petal pieces to line nest , while others use plant resin or mortar-like materials. The genus contains the world's largest bee, M. pluto (Wallace's Giant Bee), with a wingspan exceeding 6 cm.

Megachile policaris by (c) Catherine C. Galley, some rights reserved (CC BY), uploaded by Catherine C. Galley. Used under a CC-BY license.Megachile zaptlana by (c) John Rosford, some rights reserved (CC BY), uploaded by John Rosford. Used under a CC-BY license.Megachile comata by no rights reserved, uploaded by Alejandro Santillana. Used under a CC0 license.

Pronunciation

How to pronounce Megachile: /ˌmɛɡəˈkaɪli/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from other Megachilidae by the combination of: (1) female scopa on rather than legs; (2) leaf-cutting in many producing distinctive circular holes in leaves; (3) nest lined with cut leaf discs or resin. Differs from Osmia (mason bees) by leaf-cutting vs. mud/chewing behavior. Differs from Anthidium (carder bees) by absence of wool-cardering behavior. Subgenera often identifiable by structure and nesting material preferences.

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Appearance

Medium to large solitary bees with robust, somewhat cylindrical bodies. Most display black-and-white or black-and-yellow banded . Females possess a dense scopa (pollen-collecting hairs) on the surface of the abdomen, distinguishing them from leg-pollen bees. are strong and adapted for cutting leaves, manipulating resin, or excavating. Wings are membranous with reduced venation typical of Megachilidae. Body size ranges from small species under 10 mm to M. pluto at approximately 39 mm body length.

Habitat

Highly diverse: occupies forests, grasslands, deserts, agricultural landscapes, and urban environments. Nests in pre-existing cavities including hollow twigs, borings, tunnels, ground burrows, and artificial substrates such as hotels or drilled wooden blocks. Some nest in active arboreal mounds (M. pluto).

Distribution

distribution spanning all continents except Antarctica. Particularly diverse in tropical and warm temperate regions. North America numerous native ; M. rotundata introduced globally for pollination. M. sculpturalis (giant resin ) introduced to eastern North America from Asia and spreading.

Seasonality

Activity patterns vary by and climate. Most temperate species active from late spring through summer. Males typically emerge and are active before females. M. rotundata managed to coincide with alfalfa bloom. In tropical regions, some species may have extended or year-round activity periods.

Diet

feed on nectar; larvae consume pollen provisions supplied by females. Specific floral associations vary by ; many are foragers. M. rotundata strongly associated with alfalfa (Medicago sativa). Some species show preference for Asteraceae, Lamiaceae, or other plant .

Host Associations

  • Helianthus annuus - floral Sunflower pollination by M. mendozana
  • Medicago sativa - floral Primary of commercially managed M. rotundata
  • Xylocopa - nest site competitor/resourceM. sculpturalis and others occupy abandoned galleries
  • Melittobia - recorded from M. mendozana nests
  • Gasteruptiidae - attacking nests
  • Leucospidae - attacking nests
  • Sapygidae - attacking nests
  • Coelioxys - kleptoparasiteCuckoo bee laying in Megachile nests
  • Nasutitermes - nest substrateM. pluto nests in active arboreal mounds

Life Cycle

Solitary development with no . Female constructs linear series of in cavities, provisioning each with pollen ball and single . Cells sealed with leaf discs, resin, or other materials. Larva hatches, consumes provision, , spins cocoon, and pupates. Many undergo extended prepupal . emerge by chewing through cell caps; males precede females.

Behavior

Females cut circular leaf or petal pieces using , transporting them to nest sites. Some collect plant resin in mandibles for nest construction. Nesting substrate preferences vary: M. lanata uses leaf material and red earth; M. disjuncta uses wax- mixtures; M. campanulae and M. sculpturalis use resin. Optimal cavity diameters typically 0.8–1.0 cm, with species-specific variation. Males patrol and defend nest territories, engaging in aerial combat.

Ecological Role

Important of wild plants and crops, including alfalfa, sunflowers, and blueberries. Leaf-cutting activity creates minor plant damage with negligible ecological impact. Serve as for diverse and kleptoparasitic insects, supporting complexity. Nest construction in pre-existing cavities contributes to cavity-nesting insect dynamics.

Human Relevance

M. rotundata is the second most important managed globally after honey bees, used commercially for alfalfa seed production. Artificial nest blocks and hotels support in agricultural and urban settings. Some (M. sculpturalis) are non-native invasives with unknown ecological impacts. M. pluto is a flagship species for conservation, threatened by loss from oil palm expansion.

Similar Taxa

  • OsmiaAlso Megachilidae with abdominal scopa, but uses mud or chewed materials rather than cut leaves or resin
  • AnthidiumMegachilidae with abdominal scopa, but collects plant wool/fibers rather than cutting leaves
  • CoelioxysKleptoparasitic megachilids with pointed for inserting into ; often found near Megachile nests
  • XylocopaLarge carpenter bees that excavate wood; Megachile often reuse abandoned Xylocopa tunnels

More Details

Commercial Management

M. rotundata is reared on industrial using artificial nest blocks with drilled holes or grooved boards. are transported to alfalfa fields and managed with temperature-controlled incubation to synchronize with bloom.

Conservation Status

M. pluto (Wallace's Giant ) is IUCN-listed as Vulnerable due to loss from deforestation and oil palm plantations in Indonesia. Rediscovered in 2019 after no confirmed observations since 1981.

Subgeneric Diversity

The contains 56 recognized subgenera including Chalicodoma (resin bees including M. pluto and M. sculpturalis), Callomegachile, and Chelostomoides, reflecting broad ecological and morphological diversification.

Synthetic Material Use

M. rotundata and M. campanulae were among the first insects documented using synthetic materials (plastic-like substances) for nest construction, observed incorporating these into caps.

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Sources and further reading