Halictidae: Alkali Bees, Sweat Bees and Cuckoo Bees

categories: Bees Halictidae Pollinators

last review date: 2026-04-26 08:23

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.

Attracting and Keeping Natural Enemies and Pollinators in Your Yard and Garden

• Avoid regular use of synthetic, broad-spectrum pesticides.
• Infrequent use of certain narrow-spectrum pesticides is more compatible with some beneficials but generally the less chemical inputs there are, the greater and more diverse the beneficial insect community will be.
• Extensive lawns are also not conducive to attracting and retaining a diversity of beneficial insects, mites and spiders. Minimize lawn areas and maximize shrub and bush plantings.
• Many beneficials reside naturally in riparian and other ‘natural’ areas near to many back yards. Natural dispersion from these refuges ensures that some beneficials will visit back yards but they will not stay unless food, host and shelter resources are available.
• Native plants have closer affinities with native insects and therefore provide most of these resources. A garden with a good diversity of local native flora in and around back yards, will improve the abundance and diversity of local, beneficial arthropods.
• Native flora also provides natural overwintering sites for many beneficial insects and it is useful to leave at least a small area of native vegetation undisturbed during fall and winter.
• Some kinds of beneficial insects (e.g. lady beetles, lacewings, predatory mites) are available for purchase from commercial suppliers. However, benefits from introducing these beneficials are usually limited and short-lived. Upon release, commercially obtained lady beetles and lacewings often disperse and may rapidly leave your backyard despite the presence of prey and suitable nectar resources. Generally, it is more effective and sustainable to create a garden habitat that will be colonized by beneficials naturally.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

• None recommended