Megachile latimanus
leafcutting bee

Leaf cutting bees, Megachile latimanus, live in the western parts of Canada and the United States, New Zealand, South America, and Europe. This species was accidentally introduced into North America during World War II through the movement of nests in crated war material. Once in North America, they developed large populations under favorable conditions. (Essig, 1926; Manitoba Forage Seed Association, 2004)

This species prefers a dry, warm habitat with temperatures exceeding 69 degrees Farenheit. Although Megachile latmanus is most active under these conditions, this species needs a colder temperature in order to break diapause and complete metamorphosis. (Manitoba Forage Seed Association, 2004)

Most leafcutting bees are moderate-sized, stout-bodied and dark colored. They average about 10 to 20 millimeters in length. Leafcutting bees, like other bees, are covered in tiny, branched body hairs that assist in collecting pollen. This particular species carries pollen on a brush of hair on the ventral side of the abdomen. Males have 13 antennal segments and 7 abdominal tergites, whereas the females have 12 antennal segments and 6 abdominal tergites. Like most other bee species, leafcutting bees have an elongated tongue for reaching the nectar of flowers. (Borror and White, 1970; Borror, et al., 1981)

Leafcutting bees develop in the same way as other Hymenoptera, undergoing complete metamorphosis. First larvae hatch from an egg, then as the larvae grows it passes through several instars (stages of growth) each ending with a molt of the exoskeleton. Once the larvae has fully matured it enters the pupal stage where it does not eat or move, but transforms into its adult morphology.

Leafcutting bees reproduce sexually. This species mates on or around the nest. Usually during the morning, a male will seek out a female and attempt to mate by pulling at the tip of the female's abdomen. If the female is receptive, she will evert her stinger, allowing mating to take place. (Manitoba Forage Seed Association, 2004)

A female will produce about one egg per day and an average of about 28 in a lifetime. As with all hymenoptera, the fertilized eggs will be female and unfertilized eggs will be male. (Manitoba Forage Seed Association, 2004)

The females of this species provisions the nest with enough food for the larvae to eat throughout its developement. Megachile latimanus females lay their eggs on the larval food supply so as to guarantee the larvae will be able to grow. After the female lays her egg she seals the nest in order to protect the developing insect. Once the nest is plugged, there is no further parental involvement. (Serrano, 2005)

Females of this species live for at least one year, although little more is known about the lifespan of this species.

One of the most distinguishing characteristics of leafcutting bees is their nest building behavior. Once a suitable tunnel has been found, usually a hole bored in wood or crevices in between rocks, a bee will build a thimble-shaped tube using leaf cuttings. Equipped with large mandibles, the bee cuts circular discs from the leaves of rose bushes and shrubs to build its nest. Bees transport the leaves by rolling them between their legs. In the first cell of the tunnel, the bee uses small, round leaves and then larger oval pieces. Plant juices and bee secretions are used as a paste to hold the leaves together. The bee will then fill the tube with a pollen and nectar mix and lay an egg on top of the food supply. Using more circular leaf cuttings, the bee then builds a tight fitting plug for the nest, which makes the nest water proof. Leafcutter bees are solitary insects.

After comleting metamorphosis within their nests, most adults will remain withing the nest to overwinter, chewing their way out of the cell the following spring. (Andrewes, 1969; Comstock, 1947; Manitoba Forage Seed Association, 2004; Serrano, 2005)

Since this bee is a solitary insect little is known of their communication habits.

Leafcutting bees and their larvae feed on the nectar and pollen of legume flowers such as alfalfa and sweet clover. Their diet consists of about 64% nectar and 34% pollen. In order to obtain the nectar and pollen, a bee pries open the keel of a flower while inserting the proboscis (tongue) to suck the nectar. While sucking the nectar, a bee will collect pollen by rubbing against the stamen. To feed its larvae, a bee regurgitates the nectar and brushes off the pollen. (Borror, et al., 1981; Manitoba Forage Seed Association, 2004)

There are many parasites of leafcutting bees. Many species of flies, wasps (Mutillidae) and beetles (Rhipiphoridae, Meloidae, and Cleridae) parasitize the bees and their larvae, including Coelioxys bees that lay their eggs in the nests of M. latimanus to steal the food of the M. latimanus larvae. Certain ant species in the Crematogaster genus have also been known to attack leafcutter bee nests. (Serrano, 2005; Serrano, 2005; Serrano, 2005; Serrano, 2005; Serrano, 2005)

Leafcutting bees are important pollinators in natural and agricultural ecosystems.

This species of bees is important to the alfalfa industry in Canada and the United States. Leafcutter bees have been domesticated in these areas for farming purposes because of their alfalfa pollinating efficiency, ease of management, and usually rapid increase in populations. These bees adapt to a wide variety of climatic, nesting, and foraging conditions and maintain populations through the presence of predators, parasites, and insecticide poisoning. (Essig, 1926; Manitoba Forage Seed Association, 2004)

Leafcutter bees damage the leaves of plants in order to build nests, but the good they do by pollinating plants far outweighs the damage in cutting the leaves. (Essig, 1926)

This species is not in any danger of becoming extinct.

The common name of this species, leafcutting bee, is derived from its nesting behavior. (Andrewes, 1969)