ID GUIDE TO WILD BEES
OF THE NATIONAL BUTTERFLY CENTER
Mission, Texas
DARK SWEAT BEES
& SPHECODES CUCKOO BEES
Tribe Halictini: Halictus, Lasioglossum & Sphecodes
DARK SWEAT BEES
Genus Halictus, Lassioglossum & Sphecodes
Tribe Halictini
Halictidae, tiny nonaggressive "sweat bees," comprise one of the seven bee families in the order Hymenoptera. Sweat bees are a highly important group of wild 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 Lasioglossum. Bees of both of these genera tend to be small to very small; are usually black, dark brown or dark-metallic; and often have pale stripes of hair on their abdomens. Females have dark faces and legs and carry pollen on scopae (sticky brushes) located on their hind legs. Males often have partly-yellow faces and legs.
Halictus and Lasioglossum sweat bees belong to the bee tribe Halictini (and to the larger subfamily Halictinae). Sphecodes cuckoo bees, also featured on this guide page, are parasitic species that belong to the same Halictini bee tribe. Cuckoos of the genus Sphecodes prey on the nests of both Halictus and Lasioglossum sweat bees, and resemble them in size and other general characteristics.
HALICTUS SWEAT BEES OR "FURROW BEES"
Halictus sweat bees, also known as furrow bees, are found throughout 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.
Examples of Halictus sweat bees are shown in the photo strip at right: Texan Halictus bees are darkly colored, or metallic bronze or bronze-green. All have bands of pale hair on their abdomens.
Halictus bees nest in the ground, in loose soils. Some Halictus bees are solitary, and others nest in semi-social groups that pass through multiple generations in a single summer.
Halictus sweat bees are frequent visitors to flowering plants at the National Butterfly Center throughout the year. The most common of these is the ligated sweat bee, shown at right in the guide entry below.
LASIOGLOSSUM SWEAT BEES
Lasioglossum sweat bees tend to be generalist pollinators, although some species specialize on 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.
The genus Lasioglossum is 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”.
Examples of Lasioglossum sweat bees are shown in the photo strip above right. Texan Lasioglossum are usually darkly colored or metallic, and they usually have pale stripes of hair on their abdomens. At the National Butterfly Center, the most commonly seen Lasioglossum are bronze-metallic bees belonging to the subgenus Dialictus, shown in the guide entry below.
A male ligated furrow bee (Halictus ligatus)
A female Poey's furrow bee (Halictus poeyi)
Examples of Halictus and Lasioglossum Sweat Bees
A metallic Lasioglossum (Dialictus) sweat bee measurrng 3.5 mm
Lasioglossum vs. Halictus striped sweat bees:
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 at right, 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 edge or rim of each abdominal segment (the edge closer to the abdomen's tip). This is also shown in the photo strip at right.
In addition, the veins on the outer edges of Lasioglossum sweat bees' wings are indistinct. By contrast, the wing veins of Halictus bees found in our area are more boldly defined.
How to distinguish Halictus and Lasioglossum Sweat Bees
A Sphecodes cuckoo bee
SPHECODES CUCKOO BEES
Sphecodes means "like a wasp" in Greek. Sphecodes cuckoo bees are slender, with black heads; black thoraxes; and sleek abdomens that are either black, red or a combination of black and red. The bees' bodies are often coarsely pitted and their thoraxes, abdomens and legs tend to be sparsely-haired.
As noted above, Sphecodes are cleptoparasites that prey on Halictus, Lasioglossum and green metallic sweat bees. They occasionally invade the nests belonging to other bee genera as well (such as Colletes, Perdita and Andrena mining bees).
Most of the cuckoo bees shown elsewhere in this guide lay eggs in their hosts' nests, confident that their cuckoo larvae will outcompete or destroy the hosts' larvae upon hatching. Many Sphecodes bees, however, instead destroy the eggs of their hosts upon entering nests to lay eggs. Occasionally, adult Sphecodes bees move into the nests of their hosts and cohabit with them.
According to the Discover Life database, six species of Sphecodes bees have been documented in Texas (Sphecodes atlantis, S. brachycephalus, S. confertus, S. dichrous, S. heraclei, and S. mandibularis). There are 72 recorded Sphecodes species in the United States and Canada. A single species of Sphecodes -- the Hercules Sphecodes cuckoo bee -- has been observed at the National Butterfly Center. This species is shown below.
Sphecodes vs. Halictus and Lasioglossum sweat bees: Sphecodes cuckoo bees are sometimes mistaken for Halictus or Lasioglossum sweat bees. Sphecodes bees, however, differ from sweat bees in a few general respects: (1) female Sphecodes bees lack scopal hairs on their legs, because they do not collect pollen: they drink nectar and feed their young by pirating the provisions of other bees; (2) as noted, Sphecodes bees, particularly females, often have red or partly-red abdomens (while this trait is uncommon in non-parasitic sweat bees); (3) Sphecodes males do not have yellow on the clypeus (the face-part above the jaws, yellow in many sweat bee males); (4) the thorax and vertex of Sphecodes bees are often roughly pitted; and (5) a final, fairly nuanced trait also distinguishes the Sphecodes bee: the basal vein of the bee’s wing (shown in the last photo strip at right) is strongly arched, and the bees’ wing veins generally are well-defined.
Distinguishing traits of Sphecodes cuckoos bees
TAXONOMY OF DARK SWEAT BEES
AND SPHECODES CUCKOO BEES:
Halictus Sweat Bees
Order: Hymenoptera
Family: Halictidae
Subfamily: Halictinae
Tribe: Halictini
Genus: Halictus
Species: Halictus Ligatus (Ligated sweat bee)
Lasioglossum Sweat Bees
Order: Hymenoptera
Family: Halictidae
Subfamily: Halictinae
Tribe: Halictini
Genus: Lasioglossum
Subgenus: Dialictus (Metallic sweat bee)
Sphecodes Cuckoo Bees
Family: Halictidae
Subfamily: Halictinae
Tribe: Halictini
Genus: Sphecodes
Species: Sphecodes heraclei (Hercules Sphecodes)
Subspecies: Sphecodes heraclei heraclei
Halitcus, Lasioglossum and Sphecodes Bee Species of the National Butterfly Center
Ligated sweat bee
aka Ligated furrow bee
Halictus 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 sp.)
Mexican hat (Rabatida columnifera)
Seaside goldenrod (Solidago sempervirens)
Skeleton-leaf goldeneye (Viguiera
stenoloba)
Texas palafox (Palafoxia texana)
Plant family: Asteraceae
When seen:
September - November 2018
April & October 2019
A female ligated sweat bee
Ligated sweat bees. Despite their small size, ligated sweat bees are key pollinators of commercial crops such as apples, berries and melons. They are also among the four most important pollinators of commercial sunflowers.
At the NBC, if you look carefully at nearly any patch of composite flowers of the aster-family -- sunflowers, Mexican hat, golden-eye, 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.
Ligated sweat bees are also essential pollinators of wildflowers in a range of other plant families. These small bees visit flora as diverse as salvias, mallows, milkweeds, verbenas, ground cherry and willows.
Ligated sweat bees are blackish-brown with white bands of hair on their abdomens; dark eyes; and clear wings with brown veins. Females have dark legs; dark faces and mandibles; and dark, medium-length antennae. Females carry pollen on pale scopal hairs located on their hind legs, and often appear lugging bright yellow saddlebags overflowing with pollen.
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, golden- yellow on the front surfaces, and darkly-colored at the base on the back surfaces.
Halictus ligatus vs. Halictus poeyi: You may have noticed that these two fairly common Halictus sweat bee species look similar in photographs appearing on the Web. According to the Discover Life database, these two species are so similar morphologically that identification between them is generally based on their location. In the eastern United States, those found north of Virginia are all considered to be H. ligatus. Those found in Florida are deemed H. poeyi. Both species occur in western as well as eastern states. Where both species inhabit a given area, expert assistance is required to differentiate them.
A male ligated sweat bee
Lasioglossum (Dialictus) Sweat bee
Lasioglossum (Dialictus)
Family: Halictidae
Size: 3- 6 mm (male & female)
Associated plants at NBC:
Alamo vine (Merremia dissecta)
Plant family: Convolvulaceae
Cowpen daisy (Verbesina encelioides)
Plant family: Asteraceae
Golden prickly poppy (Argemone aenea)
Plant family: Papaveraceae
Prickly pear cactus (Opuntia engelmannii)
Plant family: Cactaceae
Spiked Malvastrum (Malvastrum americanum)
Plant family: Malvaceae
When seen:
March - November, 2018-2019
A female Lasioglossum (Dialictus) sweat bee gathering pollen from alamo vine
Female and male Lasioglossum sweat bees in a prickly poppy
Lasioglossum (Dialictus) Sweat Bees are metallic bees with a dark green, bronze or blue sheen. The bronze sweat bees shown here are typical examples of their subgenus. At the National Butterfly center, such bees may range from as small as 3 mm to about 6 mm (about 1/10 to 1/4 inches).
Dialictus bees are generally ground-nesters that build nests with loose clusters of brood cells. They tend to be generalist pollinators that forage on a seemingly endless array of plants.
At the National Butterfly Center, Dialictus sweat bees are among a small handful of bees that have been observed pollinating prickly poppies. They also appear on cactus, mallows, alamo vine and aster-family flowers.
Hercules Sphecodes Cuckoo Bee
aka Cyclops Sphecodes Cuckoo Bee
Sphecodes heraclei heraclei
Family: Halictidae
Size: 8-9 mm (female and male)
Associated plants at NBC:
Mexican hat (Rabatida columnifera)
Skeleton-leaf goldeneye (Viguiera stenoloba)
Texas palafox (Palafoxia texana)
Plant family: Asteraceae
When seen:
November 2018
Hercules Sphecodes cuckoo bees have a distinctive circular bump on the vertex (the top of the head), located behind the bee’s ocelli (small eyes). This trait is diagnostic of the species and has led to its alternate name -- the "cyclops Sphecodes bee". Males of this species have distinctive scalloped antennae.
There are two subspecies of Hercules Sphecodes: In the subspecies Sphecodes heraclei heraclei, shown here, the female bee has a partly-red abdomen, while the male bee has a black abdomen. In the subspecies Sphecodes heraclei ignitus, the female has a red thorax as well as a partly red abdomen; males have red coloration on the abdomen as well.
Hercules Sphecodes cuckoo bees have been documented feeding on a fairly wide range of plants. The female bee featured here was spied nectaring on aster-family flowers in November, alongside Halictus ligatus sweat bees.
A female Hercules Sphecodes cuckoo bee