Halictidae: Alkali Bees, Sweat Bees and Cuckoo Bees

categories: Bees Halictidae Pollinators

revision date: 2023-03-24 12:00

The alkali bee on a purple flower.
The alkali bee (Nomia melanderia), an important pollinator of alfalfa
Photo by: J. Abel

Biology

Halictidae occur worldwide and are the second largest family of bees. There are about 500 species in North America and they are small to medium-sized bees (0.1-0.8 inches) usually dark-colored and often metallic in appearance. Since many species don’t look like bees, they are often overlooked. The most well-known species is Nomia melanderi, the alkali bee, an important pollinator of alfalfa. Most halictids nest in the ground and they mass-provision their young with a ball of nectar and pollen. Halictids display a diversity in social behavior with species being solitary, communal, semi-social or completely social. Sweat bees (Agapostemon, Halictus, Lasioglossum spp.) are small (0.1-0.4 inches), widespread and abundant. Halictus and Lasioglossum bees are attracted to human sweat which they drink for the salt content. Sweat bees construct their nests in the ground preferring loose, sandy soils. The genus Agapostemon is abundant in the western U.S. and are strikingly colored, bright metallic green or blue bees. Most species have a bright metallic green head and thorax with a black and yellow striped abdomen. Fast-flying females carry pollen on hind leg hairs and visit a wide variety of flowers for nectar and pollen. They are short-tongued like all halictids and cannot extract nectar from deep flowers. Cuckoo bees (Sphecodes spp.) are cleptoparasites laying eggs in nests of other bees (usually Halictidae) with about 80 species in North America. They are small-moderate-sized bees, black and red or orange in color, sparsely haired and shiny. Cuckoo bees do not forage for pollen so do not have pollen-collecting hairs on their hind legs, but do drink nectar so do contribute to pollination. No nests are constructed, instead the larvae kill the host larvae and take over the provisions of the host bees.

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