alfalfa leafcutting bee

(Megachile rotundata)

               
Conservation Status

IUCN Red List

not yet assessed

alfalfa leafcutting bee

NatureServe

NNA - Not applicable

SNA - Not applicable

Minnesota

not listed

Nativity

Native to southwestern Asia and southeastern Europe. Imported into the United States for agriculture by the 1940s. Naturalized.

Occurrence

Common and widespread

Flight/Season

One generation: June through August

Habitat

A wide variety of habitats

Photo by Bill Reynolds
Size

Female: 5 16 to

Male: ¼ to 5 16

 

Identification

This is a small, black, solitary, leafcutting bee. At less than a centimeter () in length, it is the smallest leafcutting bee. Females are 5 16 to long. Males are a little smaller, ¼ to 5 16 in length.

The thorax is black. The small plate covering the base of each forewing (tegula) is dark brown to reddish-brown. The hardened plate on the upper (dorsal) side of the first segment of the thorax (pronotum) is saddle-shaped. It has a small rounded lobe on each side that does not reach the tegula. The sides and rear (posterior) of the thorax are densely covered with long white hairs. The upper (dorsal) side is sparsely covered with short white hairs on the female, longer yellowish hairs on the male. The first abdominal segment is fused to the thorax and gives the thorax the appearance of having four segments.

The abdomen is black. There are six hardened plates (tergites) on the upper (dorsal) portion of the abdomen. The second through fifth tergites (T2 through T5) have a narrow, very dense patch of short, whitish, rear-facing hairs, giving the abdomen a narrowly striped appearance. The underside of the abdomen is densely covered with long, branched, electrostatically charged hairs (scopa) used for collecting pollen. On the female, the scopa are entirely white on segments 2 through 4, white at the base with black tips on segment 5, and entirely black on segment 6. Males have white and yellow spots on the abdomen.

The head is black. The face is covered with yellowish hairs, sparsely at the top of the head, densely around the antennae and at the sides of the face. There are two large compound eyes, one on each side of the head; and three small simple eyes (ocelli) in a triangular pattern at the top of the head between the compound eyes. The antennae are thread-like and are not elbowed. They have 12 segments. The mandibles have 4 teeth. The tongue is long and slender.

The legs are black. Unlike most bees, there are no scopa on the hind legs.

 
Similar
Species

 


Larval Food

Flower nectar and pollen

 
Adult Food

Nectar and pollen of a variety of plants, but especially alfalfa.

 
Life Cycle

Breeding occurs in June and July. The female builds a tubular nest in the ground or in a crevice in rotten wood. She cuts circular disks of leaves, about 1 in diameter, placing about 15 of them at the bottom of the first cell. She then provisions the cell with pollen and regurgitated nectar, and lays a single egg. She then seals the cell with more leaf disks. She continues this process until she has laid 18 to 25 or more eggs. The larvae undergo four instar stages. Some will emerge as adults later in the summer. Others will enter a pre-pupal, hibernation-like phase (diapause), overwinter, pupate in the spring, and emerge as adults the following summer.

 
Behavior

 


Distribution Distribution Map  

Sources: 24, 29, 30.


Comments

Alfalfa Specialist
Unlike most bees, the alfalfa leafcutting bee is able to pry open the alfalfa flower, insert its long proboscis, and extract nectar. While doing this, pollen attaches to the electrostatically charged hairs on the base of the bee’s abdomen. This makes it especially well suited to pollinate alfalfa crops. The species has been exported to all parts of the world and is now found on all continents except Antarctica.


Taxonomy

Order:

Hymenoptera (ants, bees, wasps, and sawflies)

 

Suborder:

Apocrita (wasps, ants and bees)

 

Infraorder:

Aculeata

 

Superfamily:

Apoidea (apoid wasps, bees, sphecoid wasps)

 

Family:

Megachilidae (leaf-cutter bees, mason bees, and allies)

 

Subfamily:

Megachilinae

 

Tribe:

Megachilini

 

Genus:

Megachile (leaf-cutter and resin bees)

 

Subgenus:

Eutricharaea

 
Synonyms

 

 
Common
Names

alfalfa leafcutter bee

alfalfa leafcutting bee

lucerne leafcutter bee (Australia)


 

 

 

 

 

 

 

Glossary

diapause

A period of decreased metabolic activity and suspended development.

 

pronotum

The saddle-shaped, exoskeletal plate on the upper side of the first segment of the thorax of an insect.

 

scopa

A brush-like tuft of hairs on the legs or underside of the abdomen of a bee used to collect pollen.

 

tegula

A small, hardened, plate or flap-like structure that overlaps the base of the forewing of insects in the orders Lepidoptera, Hymenoptera, Diptera, and Homoptera.

 

tergum; tergite

The upper (dorsal), hardened plate on a segment of the thorax or abdomen of an arthropod. Plural: terga.

 

 

 

 

 

       

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About

Published on Oct 6, 2016

Leafcutter Bee (Megachile)

The genus Megachile is a cosmopolitan group of solitary bees, often called leafcutter bees or leafcutting bees. While other genera within the family Megachilidae may chew leaves or petals into fragments to build their nests, certain species within Megachile neatly cut pieces of leaves or petals, hence their common name. This is one of the largest genera of bees, with almost 1500 species in over 50 subgenera. North America has many native Megachile species. The introduced alfalfa leafcutter bee (Megachile rotundata) is managed for crop pollination.

Nests are sometimes constructed within hollow twigs or other similarly constricted natural cavities, but often are in burrows in the ground. Nests are typically composed of single long columns of cells, the cells being sequentially constructed from the deepest portion of the tunnel outwards. The female places an egg in each cell with a supply of food, generally pollen, sometimes mixed with nectar. She builds a cap and walls off the cell. The larva hatches from the egg and consumes the food supply. After moulting a few times, it spins a cocoon and pupates, often after several months of hibernation as a prepupa. It emerges from the nest as an adult. Males, which are typically smaller and emerge in advance of females, die shortly after mating, but females survive for another few weeks, during which time they build new nests. Numerous families of wasps and bees parasitize Megachile nests, including Gasteruptiidae, Leucospidae, Sapygidae, and various cleptoparasitic megachilids, such as the closely related genus Coelioxys. Megachile rotundata and Megachile campanulae are among of the first insects documented in scientific literature to use synthetic materials for making nests.

Notable species:
Megachile albisecta (Klug, 1817)
Megachile campanulae, bellflower resin bee
Megachile fidelis, faithful leafcutting bee
Megachile perihirta, western leafcutting bee
Megachile pluto, the largest bee in the world
Megachile rotundata, alfalfa leafcutter bee
Megachile rubi
Megachile sculpturalis, giant resin bee
Megachile texana

Leafcutting bees are important native pollinators of North America. They use cut leaves to construct nests in cavities (mostly in rotting wood). They create multiple cells in the nest, each with a single larva and pollen for the larva to eat. Leafcutting bees are important pollinators of wildflowers, fruits, vegetables and other crops. Some leafcutting bees, Osmia spp. are even used as commercial pollinators (like honey bees) in crops such as alfalfa and blueberries.

How Do They Differ From Honey Bees?

On first sighting, many species of solitary bees can easily be mistaken for honey bees or even hoverflies. So how can you tell the difference between honey bees and leafcutters, if the leafcutter is not engaged in the activity of cutting leaves or building its nest, but instead, is foraging on flowers?

One give away lies in their methods for collecting pollen. Worker honey bees, like bumblebees, collect pollen in their pollen baskets or ‘corbicula’ on the hind legs, then transport it back to the hive or nest.

Leafcutter bees do not have pollen baskets on their hind legs. Instead, they collect pollen on hairs on the underside of their abdomens. When the bee is carrying pollen, it is quite visible as a pale yellow colour.

 
     
  Alfalfa Leafcutter Bee-Megachile rotundata L.-female~By Dragana M. Redzic, Serbia
Dragana M. Redzic
 
   
 
About

Published on Jul 7, 2016

ღ SLEEPING ON LAVENDER ღ
Alfalfa Leafcutter Bee - Megachile rotundata L. - female ~ By Dragana M. Redzic, Serbia
Recorded : July 7, 2016 in 8:04 PM in Arandjelovac city, Sumadia Region, Serbia;
Frame width: 1929
Frame height: 1080
Frame rate: 29 frames/second
Data rate: 15024 kbps
Total bitrate: 15151 kbps

 
     
  Alfalfa Leafcutter Bee (Megachilidae: Megachile rotundata) Close-up of Female on Ledge
Carl Barrentine
 
   
 
About

Published on Jul 25, 2011

Photographed at Grand Forks, North Dakota (25 July 2011). Thank you to John Ascher (@Bugguide.net) for identifying this specimen!

 
     
  Leafcutting bee (#252)
nature1upclose
 
   
 
About

Published on Jun 23, 2011

 
     

 

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8/23/2017

Location: Pennington Co MN

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