Megachilidae

Latreille, 1802

Mason Bees, Leafcutter Bees, Carder Bees, Resin Bees

Subfamily Guides

Lithurginae(woodborer bees)
Megachilinae(mason bees)

is a of solitary bees distinguished by carrying pollen on specialized hairs (scopa) located on the surface of the rather than on the hind legs. The family includes diverse nesting : mason bees use soil or mud, leafcutter bees construct from circular leaf sections, carder bees collect plant or animal hairs, and resin bees use plant resins. Most are important of agricultural crops and native plants, while a minority are kleptoparasites that lay in the nests of other megachilids.

Megachile rotundata by (c) Amy Schnebelin, some rights reserved (CC BY), uploaded by Amy Schnebelin. Used under a CC-BY license.

Trachusa dorsalis by (c) Kyle Rossner, some rights reserved (CC BY), uploaded by Kyle Rossner. Used under a CC-BY license.

Stelis lateralis by (c) skitterbug, some rights reserved (CC BY), uploaded by skitterbug. Used under a CC-BY license.

Pronunciation

How to pronounce Megachilidae: //ˌmɛɡəˈkɪlɪdiː//

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

Identification

Distinguished from other by the abdominal scopa—pollen is carried on the underside of the rather than on the hind legs (corbiculae in Apidae, scopae on legs in most other families). Leafcutter bees are recognized by circular cuts on leaf margins of plants. Mason bees often plug nest entrances with mud. Resin bees may be observed collecting sticky plant resins. Carder bees scrape fuzzy plant trichomes. Kleptoparasitic (Coelioxys, Stelis, Dioxys) lack scopae entirely and have more -like, slender bodies with pointed abdomens.

Images

Habitat

Diverse including forests, grasslands, deserts, agricultural areas, and urban environments. Nesting occurs in pre-existing cavities: hollow plant stems, holes in wood, rock crevices, snail shells, and artificial structures such as blocks or hollow tubes. Some nest in exposed locations using resins or plant fibers. Ground nesting is rare in this . Many species prefer sunny, sheltered locations for nest sites.

Distribution

distribution with on all continents except Antarctica. North America approximately 630 species. Global diversity exceeds 4,000 described species, representing 15–20% of all named species. Particularly diverse in temperate and Mediterranean climates, with significant radiations in deserts and tropical regions.

Seasonality

Activity periods vary by and latitude. Most temperate species are active from spring through late summer, with peak activity in early to mid-summer. Some species are or multivoltine in warmer climates. typically occurs as or within sealed nest . is often synchronized with bloom of specific plants.

Diet

All feed on nectar and pollen as . Larvae consume pollen and nectar provisions stored by females in nest . Some species are oligolectic (specialized on narrow pollen sources), while others are foragers. Kleptoparasitic species consume provisions collected by bees.

Life Cycle

Solitary nesting with no . Females construct individual nest in cavities, provisioning each with a pollen-nectar mass before laying a single . Cells are sealed with materials appropriate to the group: mud, leaf sections, resins, or plant fibers. Larvae consume provisions, several times, spin cocoons, and pupate. Most overwinter as or in natal cells. Adults emerge by chewing through cell partitions. Males typically emerge before females and die shortly after mating; females may live several weeks, constructing multiple nests.

Behavior

Females exhibit precise, repetitive in nest construction: gathering materials, provisioning , and sealing completed chambers. Leafcutter bees cut nearly perfect circular discs from leaves, carrying them curled beneath the body. Foraging involves energetic, swimming-like movements in flowers that release large amounts of pollen. Males of some defend floral territories aggressively, chasing intruders including other bees. Kleptoparasitic females enter nests before sealing to deposit ; their larvae kill host offspring and consume provisions.

Ecological Role

Critical of agricultural crops including alfalfa, blueberries, and various orchard fruits. Important pollinators of native flowering plants in diverse . Leafcutter bees are particularly effective pollinators of alfalfa due to their vibration-based pollen collection. Nest construction in cavities contributes to nutrient cycling and creates for other organisms. Some serve as for specialized .

Human Relevance

Several are commercially propagated for crop pollination, notably Megachile rotundata (alfalfa leafcutter bee) and Osmia lignaria (orchard mason bee). Artificial nest blocks are widely used to support in gardens and orchards. The non-native giant resin bee (Megachile sculpturalis) and European wool carder bee (Anthidium manicatum) have established in North America, with uncertain ecological impacts. Some species occasionally nest in inconvenient locations such as lawn equipment or building crevices.

Similar Taxa

ApidaeHoney bees, bumble bees, and carpenter bees carry pollen on hind legs (corbiculae or leg scopae) rather than ; most are social or have different solitary nesting habits.
HalictidaeSweat bees are generally smaller, often nest in ground, and carry pollen on hind legs; many have metallic coloration but lack the robust body form and abdominal scopa of .
ColletidaePlasterer bees have mouthparts modified for secreting cellophane-like nest linings and carry pollen on legs; they lack the leaf-cutting or mason typical of .

Misconceptions

Kleptoparasitic megachilids are sometimes mistaken for due to their slender, wasp-like bodies and lack of pollen-carrying structures. The is occasionally confused with social bees, but all are solitary with no . The circular leaf cuts made by leafcutter bees are sometimes mistaken for or mechanical damage rather than intentional insect .

More Details

Subfamily Classification

comprises two : Fideliinae (tribes Fideliini and Pararhophitini) with three primarily in southern Africa and the Palearctic, and Megachilinae with seven tribes including the diverse Osmiini, Anthidiini, Megachilini, and Dioxyini.

Commercial Pollination

Megachile rotundata is the second most important managed in North America after the , with billions of individuals produced annually for alfalfa seed production. Osmia lignaria and related are increasingly used in orchard pollination as alternatives to honey bees.

Kleptoparasitism

Multiple within have evolved kleptoparasitism independently: Coelioxys (parasitizes Megachile), Stelis (parasitizes various megachilids), Dioxys (parasitizes Megachile, Anthidium, Osmia), and others. These lack scopae and have pointed for inserting into .