Halictus ligatus (Ligated Furrow Bee)

Aug 24

Quick ID & why it matters

Halictus ligatus is a very common North American “sweat bee” (family Halictidae). It nests in the ground, often thrives in cities, and is primitively eusocial—small colonies with a queen and workers. As a broad floral generalist, it pollinates many native prairie/woodland forbs and also urban garden plants.

Ecological role

Generalist pollinator. Short-tongued and happy on small, open, composite blooms; studies repeatedly link H. ligatus with Asteraceae (yarrow, fleabane, asters, goldenrods). In field datasets, H. ligatus showed strong associations with yarrow and other composites, and it visited one of the widest ranges of flowers among bees tested.
Urban resilience. It’s among the most frequently encountered native bees in cities (including Chicago), turning up on green roofs and urban prairies; research has even examined body-size variation of H. ligatus in Chicago/Detroit/St. Louis.

Life cycle (Upper Midwest / Chicago timing)

Overwintering: Mated females (“gynes”) overwinter in soil. PMC
Spring nest founding: Overwintered females emerge in late spring (around late May–early June at similar latitudes) and found nests—usually singly, sometimes with multiple foundresses.
Worker phase: First brood produces workers that take over foraging and nest duties through summer.
Reproductive phase: Late summer broods include new males and gynes; the original queen and workers die by season’s end, and the new gynes mate and enter diapause to overwinter.

Nest architecture & depth. Nests are simple vertical burrows in level, well-drained, sparsely vegetated soil; typical depths ~11–18 cm in spring to summer, sometimes deeper later. You’ll often see a little soil “tumulus” at the entrance.

Nesting habitat to provide

Sunny, bare or lightly vegetated ground. Reserve 1–3+ m² of unmulched, well-drained soil (sandy/loamy works great). Slight south/east exposure and gentle slopes help keep soil warm and dry; warmer soils and nearby flowers are tied to higher nest densities. Scatter some small pebbles/rocks—H. ligatus is often found nesting near them. Avoid landscape fabric.
No digging/tilling. Disturbance collapses burrows; hand-weed instead.
Pesticide-free. Especially avoid systemic insecticides on bloom.
Water management. Good drainage matters; don’t routinely irrigate the nest patch.

“Host plants” (for bees = nectar/pollen plants)

H. ligatus is polylectic (a generalist), but it shows a strong pull to Asteraceae and other small, accessible flowers. Below are Chicago-region natives that together cover the whole season. (Selections reflect families and species shown to attract H. ligatus and close congeners in studies or extension trials.)

Early season (April–June)

Golden Alexanders (Zizia aurea, Apiaceae) — Early umbels for spring energy.
How to grow: Sun–part sun; medium soils; 2–3’ tall; sow outdoors in fall or cold-moist stratify ~60 days; self-sows lightly.
Wild Strawberry (Fragaria virginiana) — Low groundcover with open flowers.
How to grow: Sun; medium–dry; spreads by runners; divide runners in late summer.
Wild Geranium (Geranium maculatum) — Open, saucer-shaped blooms in part shade.
How to grow: Part shade; medium soils; clump-forming; divide in fall.
Willows (Salix spp.) — Superb catkin pollen very early (shrubby species fit yards).
How to grow: Sun; moist to average; prune after bloom; avoid heavy lawn irrigation at base.

High summer (June–August)

Clustered/Short-toothed Mountain Mint (Pycnanthemum muticum) — A documented pollinator magnet, drawing exceptionally high diversity and counts.
How to grow: Sun–part sun; average soils; spreads by rhizomes (give 2–3’); divide every 3–4 yrs; deadhead optional.
Hoary/Slender Mountain Mint (P. incanum / P. tenuifolium) — Airier habit for tighter spots.
How to grow: Sun; average–dry; less aggressive than P. muticum.
Yellow Coneflower (Ratibida pinnata, Asteraceae) — Open composite disk ideal for short-tongued bees.
How to grow: Sun; medium–dry; 3–5’; stake in rich soils; fall-sow or cold-stratify.
Heliopsis (Heliopsis helianthoides, Asteraceae) — Long bloom; easy nectar access.
How to grow: Sun; average soils; pinch in June to reduce flop; divide clumps.

Late season (Aug–Oct): the critical “fat-up for winter” window

Aromatic Aster (Symphyotrichum oblongifolium, Asteraceae) — Dense late nectar/pollen; compact habit good for gardens.
How to grow: Full sun; dry–medium; shear ⅓ in late June to keep bushy; no rich fertilizer.
New England Aster (S. novae-angliae) — Tall, very high value late forage.
How to grow: Sun; medium; pinch in June; supports masses of late bees.
Showy or Stiff Goldenrod (Solidago speciosa / S. rigida, Asteraceae) — Clumping, garden-friendly goldenrods (less aggressive than S. canadensis).
How to grow: Sun; medium–dry; fall-sow seed or cold-stratify; leave stems overwinter.
Common Yarrow (Achillea millefolium, Asteraceae) — H. ligatus shows strong associations with yarrow in datasets.
How to grow: Sun; lean/dry soils best; spreads—consider edging.

Why these? Experimental and field studies repeatedly tie H. ligatus to Asteraceae (yarrow, fleabane, asters, goldenrods) and show it uses a large diversity of flowers; mountain mints are top performers for overall bee traffic and diversity. Together these give continuous bloom April–October in Chicagoland.

Garden setup & maintenance tips (Chicago-centric)

Continuous bloom: Aim for 10–15 species spanning spring → fall; ensure at least 3–4 strong late-season plants (asters/goldenrods/yarrow).
Structure: Cluster each species in drifts (1–1.5 m²) so bees can forage efficiently.
Stems & leaves: Leave spent stems (15–25 in) and leaf litter over winter; cut back in late spring.
Water & soil: Average, not overly rich soils; avoid frequent fertilizer—lush growth can flop and reduce bloom.
No neonics: Skip systemic insecticides; spot-treat weeds by hand.
Nesting patch: Keep a sunny, bare, well-drained 2×2 m (or as big as you can) soil area near the flowers; don’t mulch it. Add some pebbles/gravel; maintain year to year.

A few field notes

What you’ll see: Small dark bees with pale abdominal hair bands; males slimmer with longer antennae. Expect them from late spring through fall, especially heavy on late asters/goldenrods and on mountain mints in midsummer.
Behavior: They’re called “sweat bees” because salt attracts them; stings are uncommon and mild.

Scott Macdonald