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ID GUIDE TO WILD BEES
OF THE NATIONAL BUTTERFLY CENTER
Mission, Texas

Halictus ligatus;  Copyright 2019 Paula Sharp

DARK SWEAT BEES OR FURROW BEES
  Halictus & Lasioglossum

DARK SWEAT BEES OR FURROW BEES

Genera Halictus & Lassioglossum
Tribe Halictini

Halictini -- small, nonaggressive "sweat bees," are a highly important group of native pollinators, instrumental in the propagation of an impressive range of commercial crops -- among them squash, legumes, sunflowers, watermelons, apples, berries, carrots, tomatoes and peppers, to name but a few.  Sweat bees are also essential pollinators of Texas native flora and garden flowers.

This guide page features common sweat bees belonging to the genus Halictus and the genus LasioglossumAlso known as "furrow bees," Halictus and Lasioglossum tend to be small to very small; are usually black, dark brown or dark-metallic; and often have pale bands of hair on their abdomens.  Females usualy have dark faces and legs and carry pollen on scopae (sticky brushes) located on their hind legs.  Males often have partly-yellow faces or legs.

Halictus ligatus; Copyright 2020 Ernesto Herrera

Male ligated furrow bees (Halictus ligatus)  - Photo credit Ernesto Herrera

Halictus and Lasioglossum furrow bees

 

Halictus are found throughout the world.  There are 25 species in the Americas; of these, six have been documented in Texas:  Halictus confusus, H. ligatus, H. parallelus, H. poeyi, H. rubicundus  and H. tripartitus.   All of these are dark brown or metallic bronze.

Halictus nest in the ground, in loose soils.  Some Halictus are solitary, and others nest in semi-social groups that pass through multiple generations in a single summer.   Halictus species of the Valley are broad generalist pollinators.

Lasioglossum is a much vaster genus than Halictus, represented by 280 species in North America, and by more than 150 species in Texas alone.  Hairsplitting differences among Lasiglossum species make identification of individual types challenging.  In his massive work The Bees of the World, the great entomologist Charles D. Michener dedicated twelve pages of fine print to the taxonomical traits of various Lassioglossum after describing them as "a genus of morphologically monotonously similar bees”. 

Texas Lasioglossum are black, brown, or metallic gold or bronze.  They usually have bands of pale hair on their abdomens; some have red abdomens.  In the Lower Rio Grande Valley, the most commonly seen  Lasioglossum are metallic bees belonging to the subgenus Dialictus.

Lasioglossum tend to be generalist pollinators, although some species specialize in pollinating particular plants.  Lasioglossum females usually build nests in loose soils, consisting of single narrow shafts with series of branches.  The bees secrete a waxlike substance used to line their brood cells.  The behavioral habits of this broadly-defined  genus vary widely by species:  some Lasioglossum are solitary, but others form semi-social groups or colonies.

​​Lasioglossum vs. Halictus

​Striped Lasioglossum sweat bees usually can be told from striped Halictus sweat bees by an examination of the bees' wings and the positioning of the bands girding the bees' abdomens.  


As shown in the photo strip here, on striped Lasioglossum sweat bees, the pale hair bands on the bees' abdomens usually appear on the inner edge of each segment (the edge closer to the bee's head).  Conversely, on Halictus sweat bees, the pale hair bands are on the outer rim of each abdominal segment (the edge closer to the abdomen's tip). 

In addition, the veins on the outer edges of Halictus forewings tend to be boldly defined.  By contrast, the outer forewing veins of some Lasioglossum are weakly-defined.

Lasioglossum coactum; Copyright 2023 Sharp-Eatman Nature Photography

A metallic Lasioglossum (Dialictus) coactum

Traits of Halictus and Lasioglossum furrow bees

TAXONOMY OF FURROW BEES  SHOWN HERE:
 

Halictus Sweat Bees

Order:   Hymenoptera
Family:   Halictidae  
Subfamily:   Halictinae
Tribe:  Halictini
Genus:   Halictus

Species:  Halictus (Odontalictus) ligatus
                  (Ligated sweat bee)

Lasioglossum Sweat Bees

Order:   Hymenoptera
Family:   Halictidae 
Subfamily:   Halictinae
Tribe:  Halictini
Genus:   Lasioglossum

Subgenus:  Lasioglossum (Dalictus) coactum

                    (Constricted metallic bee)

Halictus & Lasioglossum Species of the National Butterfly Center & Lower Rio Grande Valley

Ligated furrow bee

aka Ligated sweat bee

Halictus (Odontalictus) ligatus


Family:  Halictidae

Size:  7-9 mm  (male)
          7-10 mm (female)

Associated plants at NBC: 

Blanketflower

(Gaillardia pulchella)

Cowpen daisy

(Verbesina encelioides)
Hierba del marrano

(Symphyotrichum subulatum)

Mexican hat 

(Ratibida columnifera)

Seaside goldenrod 

(Solidago sempervirens)

resinbush

(Viguiera stenoloba) 

Texas palafox

(Palafoxia texana)
Plant family:  Asteraceae

 

When seen:
September - November 2018
April, October 2019

November, 2022

Halictus ligatus;  Copyright 2019 Paula Sharp

A female Halictus ligatus

Halictus ligatus;  Copyright 2019 Paula Sharp

A male ligated sweat bee 

Ligated sweat bees.  Despite their small size, ligated sweat bees are key pollinators of commercial crops; they are among the four most important pollinators of commercial sunflowers. 

 

At the NBC,  if you look carefully at nearly any patch of composite flowers  -- sunflowers, Mexican hat, resinbush, cowpen daisies, blanketflower or purple hierba del marrano -- you are likely to see several of these bees, often perched two or three to a blossom.  In the Lower Rio Grande Valley, ligated sweat bees also visit a gamut of wildflowers of other plant families, among them, salvias, mallows, milkweeds, verbenas, ground cherry and willows.  

 

Ligated furrow bees are black-eyed, dark-brown bees with white bands of hair on their abdomens, and clear wings with brown veins.  Females have dark legs; dark faces and mandibles; and dark, medium-length antennae. Females often appear lugging hefty loads of pollen on their hind-leg scopal hairs.  

 

Male ligated sweat bees have yellow legs with dark markings on them; partly-yellow faces; and mandibles that are yellow and reddish-brown. The males' antennae are long and mostly brown, with golden-yellow front surfaces.

Constricted metallic bee

Lasioglossum (Dialictus) coactum


Family:  Halictidae

Size:  4.5 - 5 mm (females and males)    

Associated plants:

wild poinsettia

(Euphorbia cyathophora)

Plant family:  Euphorbiaceae

 

shrubby blue salvia

(Salvia ballotiflora)

Plant family:  Lamiaceae

 

red prickly poppy

(Argemone sanguinea)

Plant family:   Papaveraceae

 

camphorweed

(Rayjacksonia phyllocephala)

crucita

(Chromolaena odorata)

Plant family:  Asteraceae

 

When and where seen:
November 2021
Bahia Grande NWR

Laguna Atascosa NWR

Las Palomas Refuge

(Cameron County)

Lasioglossum coactum; Copyright 2023 Sharp-Eatman Nature Photography

A female Lasioglossum coactum

Lasioglossum coactum; Copyright 2023 Sharp-Eatman Nature Photography

A male Lasioglossum coactum

Lasioglossum (Dialictus) coactum.  Metallic furrow bees of the Lasioglossum subgenus Dialictus can be very difficult to identify, in part because of their small size.  Many furrow bees of this subgenus in the Valley remain uncatalogued. 

 

Lasioglossum (Dialictus) coactum is one of the easier bees of its subgenus to identify.  it can be recognized (under strong magnification) by its constricted first and second abdominal segments (T1 and T2);  viewed from above or in profile, the segments' rims appear as if they had been pulled in tightly with a belt.

Lasioglossum (Dialictus) furrow bees engage in a wide range of behavior, from solitary to primitively eusocial.  Some, but not all, solitary varieties form large aggregations.  The bees’ nest structures range from the simple to the complex.  Most Lasioglossum (Dialictus) nest in the ground; a minority nest in pre-existing cavities created by other insects in wood.

Lasioglossum (Dialictus) tend to be generalist pollinators that forage on a seemingly endless array of plants.  In the Lower Rio Grande Valley, they are among a handful of bees that have been observed pollinating prickly poppies (Argemone)

CITE THIS PAGE:  Sharp, Paula and Ross Eatman.  "Halictus and Lasioglossum."  Wild Bees of the National Butterfly Center of Mission, Texas. 15 Jan. 2019,  http://www.wildbeestexas.com.  Accessed [day/month/year guide accessed].

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