Gardening Articles: Care :: Seeds & Propagation

The Other Pollinators (page 4 of 6)

by Amy Bartlett Wright

Leafcutter Bee (Megachile)

The squash bee isn't the only one with dining preferences. The most famous member of this large and diverse species is the alfalfa leafcutter bee, M. rotundata, which was introduced from Eurasia to pollinate alfalfa. Leafcutter bees prefer legume blossoms, and collects pollen on a brush of hairs called a scopa, on the underside of its abdomen, rather than on leg hairs.

More than 140 species of leafcutter bees are found throughout North America. Many nest in wood cavities, such as holes left in logs and branches by insects or birds. Some species nest in soil. Females cut circular pieces out of leaves, using their sharp mandibles and bending their bodies downward as they rapidly cut. These bees use the leaf pieces to line their thimble-sized cell. A female leafcutter bee packs a protein-rich mixture of pollen and nectar into the cell and then lays an egg. The larva develops in the cell while feeding on the stored food and pupates over the winter inside the lined cell. The adult emerges in spring or summer at just the right time for pollinating.

Growers who provide this bee with a specially designed, open-roofed structure partly domesticate it. Beekeepers place these structures with machine-punched holes in boards to make it easy for the bees to nest. Keepers can remove cells containing eggs and store them in a climate-controlled environment until the bees are needed for pollination.

Mason bee (Osmia)

Mason, or orchard, bees are solitary bees of the same family as leafcutter bees. A female builds nest cells that are often lined with mud or pieces of flower petals or leaves; she places them singly or in cell groups inside a wooden cavity such as a hollow plant stem or old beetle-emergence hole in dead wood. Osmia ribifloris is found only from the Rockies to West Texas, but the habitat of other mason bees ranges throughout the continental United States to Costa Rica. To attract mason bees, you can make nesting areas with boards.

Sweat Bees (Halictidae family)

Though most species of this small bee, found throughout the continental United States, are black or brownish, some, such as Agapostemon femoratus, are bright metallic green. All species nest in the ground. Halictids have a range of nesting habits, from dispersed solitary nests to densely situated ones with individual bees sharing common entranceways to primitive social arrangements. Lateral tunnels end in a single cell. Halictid bees are common insects and good general pollinators.

This bee takes its name from its habit of landing on people to lick the salt from their skin. This bee will sting only if you swat at it. (However, you shouldn't swat at any bee.)

Alkali bee (Nomia melanderi)

This native western bee nests in moist alkaline soils near natural seeps and springs. Also a halictid bee, the alkali is easily recognized by its metallic green abdominal stripes. Western scientists and farmers attract this wild bee by building nest sites that simulate natural in-ground nests in alkaline soil. Although alkali bees are solitary, individuals nest near each other. This efficient bee is adept at pollinating alfalfa, clover, mint, onions, and celery.

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