Meet the Tiny, Gentle Sweat Bees Quietly Pollinating Your Garden

Small sweat bees (Lasioglossum) are among the most abundant yet overlooked pollinators in North American gardens. These diminutive bees — some barely 1/16 inch long — are active from early spring through fall, visiting a vast array of flowers. On hot summer days, they may land on your skin to sip sweat, but don't panic: they're harmless, gentle, and more likely to tickle than sting.

Holm Design & Consulting LLC — A female small sweat bee (Lasioglossum sp.) perches on an aster. This is one of the larger species, with distinct basal abdominal stripes.

At a Glance

• Family: Halictidae
• Genus: Lasioglossum
• Species: ~290 in North America (north of Mexico); 1,760 worldwide
• Range: Every continent except Antarctica
• Habitat: Woodlands, gardens, meadows, prairies, farms, urban and suburban areas

When to Spot Them

In the northern U.S., females emerge as early as April (earlier farther south). Most species are generalists, visiting a wide variety of flowers. A few specialists exist: L. oenotherae focuses on evening primrose (Oenothera), while L. pectinatum specializes on ground cherry (Physalis).

Holm Design & Consulting LLC — Visiting Canada anemone (Anemone canadensis) in late spring.

Holm Design & Consulting LLC — Nest entrance in silt-loam soil on a Minnesota blueberry farm.

Why They Matter

Despite their size, small sweat bees are effective pollinators. Their long foraging season and ability to access tiny flowers make them valuable contributors to pollen transfer across many plant species. Females need a continuous succession of blooms to fuel nest-building and provision their offspring.

Holm Design & Consulting LLC — Note the long, thick antennae.

Identification Tips

• Adults: Slender, dark brown to metallic black/gray with pale hair bands at abdominal bases. Some species have orange/red abdomens. Size ranges from 2–12 mm. Males have longer, thicker antennae and lack pollen-carrying hairs.
• Larvae: Grub-like, pale yellow to cream. Rarely seen — they develop in underground nests or wood cavities.

Holm Design & Consulting LLC — Female small sweat bee near her nest entrance.

How to Attract and Support Them

Provide Nesting Sites

Most Lasioglossum nest in bare or sparsely vegetated, uncompacted soil; some use rotting wood. Protect nesting aggregations from disturbance. Leave patches of bare earth, especially in sunny spots.

Maintain a Pesticide-Free Yard

Avoid insecticides, particularly on flowering plants.

Holm Design & Consulting LLC — Multiple nests in close proximity.

Plant for Continuous Bloom

Offer a succession of native flowers from spring through fall:

• Spring: Bloodroot, twoleaf miterwort, wild geranium, red columbine, spiderwort, tall meadow-rue
• Summer: Purple prairie clover, yellow loosestrife, vervain, nodding onion
• Late summer/fall: Goldenrod, common boneset, asters

Holm Design & Consulting LLC

Life Cycle

In the Upper Midwest and Northeast, species produce 1–3 generations per year. Mated females overwinter underground, emerging in spring to establish nests. Solitary or primitively social, nests may occur singly or in aggregations. In multi-generation species, first-generation females often become workers; later generations produce males and new queens that overwinter.

Holm Design & Consulting LLC — Female climbing red columbine (Aquilegia canadensis) anthers.