ID GUIDE TO WILD BEES - NEW YORK
Halictidae, tiny nonaggressive "sweat bees," comprise one of the seven bee families in the order Hymenoptera. Sweat bees are responsible for the pollination of an impressive range of commercial crops -- among them squash, legumes, sunflowers, watermelons, apples, cranberries, blueberries, strawberries, tomatoes and peppers, to name but a few. Sweat bees are also essential pollinators of native flora, appearing in all seasons in New York on an extensive array of flowering plants found in woodlands and fields.
Part I of this guide's sweat bee section covers iridescent green metallic sweat bees. Part II below covers sweat bees that are dark in color, usually with striped abdomens. In our area, dark and striped sweat bees divide mainly into two large genuses -- Halictus and Lasioglossum. Below is a sampling of Halictus and Lasioglossum sweat bees inhabiting Rockefeller State Park Preserve and Stone Barns Center for Food an d Agriculture.
SWEAT BEES. 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, responsible for the pollination of an impressive range of commercial crops -- among them squash, legumes, sunflowers, watermelons, apples, cranberries, blueberries, strawberries, tomatoes and peppers, to name but a few. Sweat bees are also essential pollinators of native flora, appearing in all seasons in New York on an extensive array of flowering plants found in woodlands and fields.
Sweat bees come in a multitude of varieties and colors, and span 14 genera (genuses) within the United States. Sweat bees shown in this guide represent six distinct sweat bee genera that can be grouped roughly by their salient characteristics: (1) iridescent green sweat bees, which are covered in Part I of this guide's section on sweat bees; and (2) sweat bees, covered here in Part II, that are dark in color, often with striped abdomens or with a metallic sheen. In our area, dark sweat bees divide mainly into two large genuses -- Halictus and Lasioglossum. Below is a sampling of Halictus and Lasioglossum sweat bees inhabiting Rockefeller State Park Preserve and Stone Barns Center for Food and Agriculture.
Ligated Sweat Bee
Halictus Ligatus (Subgenus Odontalictus)
1/5 - 1/3" (very small)
Confusing Sweat Bee
Halictus confusus -- (Subgenus Seladonia)
1/5 - 1/3" (very small)
Halictus Sweat Bees. Halictus sweat bees are found throughout throughout the world. There are 25 species in the Americas, and 6 in the New York area. Halictus sweat bees native to New York are small to very small, dark brown or black bees with pale stripes of hair on their abdomens. Females have dark faces and dark legs covered with fine pale hairs, and they carry pollen on scopae (sticky brushes) located on their hind legs. Males lack scopal hairs and tend to have partially yellow legs and faces. New York’s Halictus bees are generalist foragers that pollinate a broad range of wildflowers and garden flowers as well as commercial crops. The bees 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 sweat bees are a common sight in the park and at Stone Barns Center for Food and Agriculture. They first appear in early spring and remain through mid-fall.
Ligated Sweat Bees. A ligated sweat bee is smaller than the head of a dime. If you look carefully at the coneflowers in the park's Visitor Center garden, you might well see two or three of these wild bees on a single blossom. Despite their small size, ligated sweat bees are among the four most important pollinators of commercial sunflowers. (The others are longhorn bees, sunflower bees and West Coast yellow-faced bumble bees.) Ligated sweat bees avidly frequent sunflower plantings of Stone Barns' vegetable fields. These bees are nevertheless generalist pollinators and thus are also common visitors to the gardens of Stone Barns and to wildflowers lining park trails.
Ligated sweat bees are key pollinators of wildflowers. These wild bees, however, have short tongues and are unable to forage for nectar in deep-throated blossoms. The bees are so small that when they feed on milkweed, they have to be careful not to fall into the blossoms -- if they do, they can become trapped in the flowers' sticky pollen-holding sacs (called pollinia) and expire. Nevertheless, these tiny bees have an advantage when feeding on nectar in flowers too small for large bees to enter. Ligated sweat bees are thus efficient pollinators of many species of wildflowers, among them bee balm, penstemon, goldenrod, bloodroot, rue anemone, dandelion, and violets.
Ligated sweat bees are blackish-brown with white bands of hair on their abdomens; dark eyes; and clear wings with brown veins. The females have pale scopal hairs on their hind legs and often appear lugging bright yellow saddlebags overflowering with pollen. Females have dark legs and mandibles and dark, medium-length antennae. As shown at left and in the photo strip at right, males 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 yellow mixed with reddish-brown.
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 that differentiation between them is generally based on where they are found. Populations north of Virginia are considered to be H. ligatus and those south of Virginia are deemed H. poeyi.
Taxonomy of Halictus Sweat Bees
Family: Halictidae (Sweat Bees)
Species: Halictus Ligatus , Halictus confusus, Halictus rubicundus
Halictus vs. Lasioglossum Sweat Bees. Ligated sweat bees belong to the subgenus Halictus (as well as the genus Halictus). Entomologist Charles D. Michener notes the following two traits, among others, as distinguishing Halictus sweat bees from similar striped Lassoglosum sweat bees like that shown farther below. Halictus bees have densely feathery hairs striping the rims of their second and third abdominal segments; and they have strongly marked veins in the outer parts of their wings. Neither of these is easily detectable by the casual observer. To the naked eye, ligated sweat bees appear stouter than the striped Lasioglossum bees shown near the bottom of this guide page.
Confusing sweat bees belong to the subgenus Seladonia of Halictus. Bees of this subgenus have greenish, bluish or brassy thoraxes and pale abdominal stripes. They are found throughout the United States and appear in the park and Stone Barns from May through October. Like bumblebees, confusing sweat bees are eusocial; their nests contain two generations of bees, a mother and her daughters, who work cooperatively, protecting and provisioning the nest and caring for larva after they hatch. Confusing sweat bees construct their nests in dry areas in a wide range of habitats. Their flight distance from their nests is fairly short – about 75 – 140 yards, and thus food sources must be in fairly close range of where the bees settle.
Confusing sweat bees are common pollinators of strawberries, watermelons, peppers and tomatoes. These bees are considered broad generalists. In addition to being crop pollinators, they visit an array of important native wildflowers, among them, hemp dogbane, goldenrod, mountain mint and fleabane.
Identifying traits: These are small bees, under 1/3” in length. They are dark with pale and metallic coppery stripes and covered with short, fine hairs. Although called “greenish” in the Discover life data base, confusing sweat bees are described by Xerxes.org society as having a “metallic copper sheen”. Photographs of these bees throughout the web, including those posted on bugguide.net, usually portray coppery-bronze bees rather than green ones. The bee shown here looked iridescent bronze under camera flash coupled with a macro lens (see photos at right). To the naked eye, without illumination from a strong light source setting off their iridescence, these tiny bees appear black.
The vividly yellow-and-orange legs and long antenna of male confusing sweat bees make them stand out among other small dark bees buzzing around flowers. Male confusing sweat bees also have bright yellow face parts (the mandibles, the labrum and a third of the clypeus, shown in the photos at bottom left and at right). Yellow face parts are a trait shared by other males of the genus Halictus. The clypeus of the male Halictus confusus is protuberant, a trait that helps distinghish it from similar male bees.
Halictus ligatus (female)
Halictus confusus (male), showing the bee's protuberant yellow clypeus (the part just above the jaws).
Halictus ligatus (male)
Halictus confusus (female)
All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography
All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography
Halictus Sweat Bees
Halictus Rubicundus Sweat Bee
Halictus rubicundus (Subgenus Protohalictus)
Halictus rubicundus. This is an unusal bee species. Most bees are categorized as either social, eusocial or solitary. Social bees may form highly complex colonies organized into hierarchies of queens, workers and drones. Solitary bees build individual nests. Eusocial bees are in the middle – they build nests that may house more than one bee generation and that may include, for example, a queen bee and her daughters. The social behavior of Halictus rubicundus varies depending on the climate. In warmer climates, it is eusocial, producing nests that contain small bee groups consisting of a reproductive female and her offspring. In cooler climates, the bees are solitary. Halictus rubicundus bees usually dig nests in sloping or vertical bare ground, constructing 5-7 cells in which to lay eggs. The bees leave a tell-tale small pile of excavated dirt called a “tumulus” outside their nest entrances. Halictus rubicundus nests appear singly and in aggregations.
Halictus rubicundus are fairly large for sweat bees – both males and females are about 2/5”. The bees are dark brown with sharply-defined white bands on the top portion of their abdomens. The legs of female bees are reddish-orange with pale yellow hairs. The males have yellow legs with black and reddish markings, and partly yellow faces. As shown in the photo at right, Halictus rubicundus sweat bees lack a hair band on the last segment of their abdomens; this characteristic helps distinguish them from the other Halictus sweat bees shown here. Males of this species also have predominantly black or brown mandibles. This helps tell them apart from male ligated sweat bees, shown above, which have yellow and reddish mandibles. Female halictus rubicundus have pale hairs on their faces. Their wings are reddish.
Halictus rubicundus are found throughout the northern hemisphere, in northern Asia, Europe and America. These bees are considered "highly polyetic" and are documented pollinators of an astounding variety of commercial crops including apples, plums, blueberries, melons, squash, strawberries, potatoes and sunflowers. They also pollinate garden and flowers from several plant families; they forage on wild plants as diverse as chokecherry, winterberry, spreading dogbane, fleabane, lupine, allium, delphinium, New Jersey tea, and California poppies. The male bee shown here is feeding on mountain mint. The female bee was foraging in mid-April amid a wide variety of flowering plants in a pastured area of the park's Rockwood Hall section.
These bees are preyed on by two cleptoparasitic bee species: Sphecodes gibbus and S. monilicornis.
A male Halictus rubicundus
A female Halictus rubicundus
All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography
Dialictus sweat bees frequently appear metallic, with a dark green, bronze or blue sheen. The bronze sweat bee shown above right is a typical example. Dialictus bees are generally ground-nesters that build nests with loose clusters of brood cells. They tend to be generalist pollinators.
HAIRY LASIOGLOSSUM. Among the most easily recognized Dialictus bees in our area is the Hairy Lasioglossum (Lasioglossum pilosum), shown at second right. This bee is distinctive because it has an abdomen thickly covered with tan hairs and a bright bronze-gold thorax. To the naked eye, the bee appears pale gold and fuzzy. Hairy Lasioglossum sweat bees are pollinators of milkweeds, thistles and wild roses, among many other flowering garden and native plants. They also pollinate stone fruits as well as melons, berries and apples. The Lasioglossum pilosum shown here was discovered feeding on a wild aster on the edge of a sunlit trail of Rockefeller State Park Preserve in August.
TWISTED LASIOGLOSSUM. Many species of Dialictus are nearly impossible to differentiate from one another with the naked eye. An example is the the Twisted Lasioglossum (Lasioglossum versatum). The bee shown at center right -- tentatively identified as Lasioglossum (Dialictus) resembling true L. versatum (=rohweri) -- has a dark greenish-bronze metallic head and thorax and a brownish-black abdomen covered with fine pale hairs. These characteristics are shared by many Dialictus and thus minute inspection and expert assistance are often necessary for this species' certain identification. Lasioglossum versatum forages on a a broad range of garden flowers, such as chrysanthemums, black-eyed Susans, fleabane, Queen Anne’s lace, dandelions, clover, thistles and viburnum. This small bee is also a pollinator of such crops as melons, strawberries, blueberries and caneberries. The bee shown here was found foraging on goldenrod at Stone Barns in August.
TEGULAR LASIOGLOSSUM. A third example of a metallic Dialictus sweat bee is the Tegular Lasioglossum Sweat Bee (Lasioglossum tegulare). This is a very small, slender bee that looks nearly black to the naked eye. Females of this species are 1/5” or smaller; males, like the one shown here, are closer to 1/6”. Under magnification, the bee’s head, thorax and abdomen have a coppery-bronze sheen. Pale hairs sprout from the bee’s face and cheeks, and sparse bands of longish white hair ring some of the bee’s abdominal segments. This species’ name, tegulare, derives from tegula, the part of a bee where the wing attaches to the insect’s body. On this species, the tegula is irregularly shaped. (Tegula are usually oval and symmetrical, but on this bee, the inner edge of the tegula is flattened or slightly concave with a slight inward-pointing projection at the back. This nuanced trait exemplifies the subtleties involved in distinguishing one Lasioglossum species from another.)
This miniscule sweat bee is a pollinator of apples, blueberries, caneberries, melons and strawberries. Tegular Lassioglossum are also pollinators of many native wildflowers, among them viburnum, swamp milkweed, goldenrod, fleabane, bee balm, sneezeweed, yellow indigo, wild rose, fringed loosestrife and buttercups. The male bee shown here was found feeding on goldenrod in September.
All photos (c) 2014 - 2017 Sharp-Eatman Nature Photography
A dark Lasioglossum sweat bee with a striped abdomen (female)
LASIOGLOSSUM SWEAT BEES are slender, small bees, ranging between 1/2" and 1/10" in length. They are often darkly colored, with or without pale bands of hair on their abdomens; some are metallic. Males sometimes have partly yellow faces or legs.
Female Lasioglossum sweat bees carry pollen conspicuously, on scopal hairs located on the upper sections of their hind legs, like the bee shown at right. This bee, found nectaring on a wild rose at Stone Barns in late spring, is a typical dark Lasioglossum: it is slender, dark-bodied and barely 1/4" long, with narrow off-white bands on its abdomen. The bee below it is a typical metallic Lasioglossum -- a 1/4" dark bronze bee with short, pale hairs on its head, legs and body.
Lasioglossum sweat bees tend to be generalist pollinators, although some species specialize on particular plants. Lasioglossum sweat bees appear in the park and Stone Barns wherever flowers abound. Despite their size, Lasioglossums are considered chief pollinators of wildflowers, garden flowers and vegetable crops.
Sweat bees of the genus Lasioglossum tend to 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 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 sweat bees:
Striped Lasioglossum sweat bees usually can be told from striped Halictus sweat bees (shown higher up on this guide page), by examining the bees' wings and the positioning of their stripes.
As shown in the photo strip at right, 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 boldly defined throughout.
In addition, on striped Lasioglossum sweat bees, pale striping appears on the inner edge of each segment (the edge closer to the bee's head). Conversely, on Halictus sweat bees like the striped ligated sweat bee shown higher up on this page, the pale hair bands are on the outer edge or rim of each segment (the edge closer to the abdomen's tip). This is also shown in the photo strip at right.
The sweat bee genus Lasioglossum is represented by 280 species in North America, and 170 in New York alone. Hairsplitting differences among Lasiglossum species make identification of individual types challenging. The great entomologist Charles D. Michener dedicated twelve pages of fine print to the taxonomical traits of various Lassioglossum in The Bees of the World, after describing them as "a genus of morphologically monotonously similar bees”.
There are five subgenera (subgenuses) of Lassioglossum in the United States and Canada. Four have been found in the park and Stone Barns: Dialictus; Lasioglossum; Sphecodogastra; and Evylaeus. A sampling of these is shown below.
Taxonomy of Lasioglossum Sweat Bees
Family: Halictidae (Sweat Bees)
Subgenuses shown here:
Dark, Striped Lasioglossum Sweat Bees
Lasioglossum coriaceum (Subgenus Lasioglossum)
1/3" -1/2" (medium-sized)
Lasioglossum quebecense (Subgenus Sphecodogastra)
Evening Primrose Lasioglossum
Lasioglossum oenothera (Subgenus Sphecodogastra)
Lasioglossum (Evylaeus) Dark Sweat Bee
Lasioglossum Subgenus Evylaeus sensu lato
1/6' - 1/4" (very small to small)
Dark Lasioglossum sweat bees with striped abdomens are common throughout the spring and summer in the park and Stone Barns. Such bees typically fall into one of three subgenera - - the redundantly named subgenus Lasioglossum; the subgenus Sphecodogastra; and the subgenus Evylaeus. Examples of these three groups are shown here.
LEATHERY LASIOGLOSSUM. The male bee shown at top right, called a Lasioglossum coriaceum, is a member of the subgenus Lasioglossum (as well as the genus Lasioglossum).
This species is notably large for a sweat bee -- nearly 1/2" long. The bee has a slender, elongated black abdomen ringed with well-defined bands of white hair and dark wings. Males have a distinctive appearance -- as shown in the photo strip at right, males have exceptionally large jaws and distinctive yellow masks on their faces. Other nuanced traits (a broad cheek and dark distitarsi) help identify females of this species.
These bees are broad generalists and appear in August in the park and at Stone Barns on numerous flowering plants. Leathery Lasioglossums show a preference for small-blossomed plants such as goldenrod, Queen Anne's lace, catmint and other mints. They are documented pollinators of a variety of crops, including apples, melons, blueberries, strawberries and caneberries.
Lasioglossum Sweat Bees
A metallic Lasioglossum sweat bee (female)
Dark Metallic Lasioglossum (Dialictus) Sweat Bees
1/5' - 1/4" (very small)
A Female Quebec Lasioglossum (Lasioglossum quebecense)
(Subgenus Sphecodogastra) - 1/4"
A Female Evening Primrose Lasioglossum (Lasioglossum oenothera)
(Subgenus Sphecodogastra) - 3/10"
A Female Lasioglossum (Dialictus) Sweat Bee with metallic coloration
A Male Tegular Lasioglossum (Lasioglossum tegulare) (Subgenus Dialictus)
A tentatively identified female Lasioglossum versatum (Subgenus Dialictus)
EVYLAEUS DARK SWEAT BEE. Lasioglossum sweat bees of the subgenus Evylaeus are ground nesters that construct nests with turrets at the entrances and tightly-clustered brood cells. According to entomologist Charles D. Michener, the Evylaeus subgenus includes species with more complex social behavior than the Dialictus sweat bees shown directly below.
Many Evylaeus sweat bees are generalist pollinators. These bees are frequent visitors to the agricultural fields of Stone Barns and to native woodland flowers in the park.
Evylaeus sweat bees tend to be dark and to lack metallic coloration. The male Evylaeus sweat bee shown at bottom right is fairly typical of its subgenus. It is a non-metallic black and so long and slender as to seem antlike. The bee is also quite small - barely 1/5 inch in length. Pale hairs on the bee's abdomen are invisible to the naked eye.
To the naked eye, Evylaeus sweat bees are similar in appearance to other varieties of small dark bees appearing in this guide, particularly small carpenter bees. Minute inspection is often necessary for identification.
EVENING PRIMROSE LASIOGLOSSUM.
The female bee at third right is an evening primrose Lasioglossum (Lasioglossum oenotherae), another member of the subgenus Sphecodogastra.
This is a relatively large dark sweat bee, about 1/3" long, with weakly-defined pale abdominal stripes, a broad head and long jaws with reddish tips. Male Lasioglossum oenotherae bees have yellow-and-black faces and legs.
This sweat bee species specializes on Oenothera, a flowering plant commonly known as evening primrose, which belongs to the plant family Onagraceae,. Oenothera is native to the Americas, although the evening primroses most often seen in New York wild lands are escaped yellow garden varieties that have naturalized in grassy areas. Primrose Lassioglossums have been documented feeding on goldenrod as well.
Female evening primrose Lasioglossums have conspicuous pale scopal hairs on the middle sections of their hind legs, while their hind femurs are less hairy. According to entomologist Charles D. Michener, the scopae of Lasioglossum oenothera are specially adapted for gathering nutrients from members of the plant family Onagraceae, whose pollen is webbed and thus sticks well to itself.
The bee shown here appeared pollinating an escaped garden Oenothera in a pasture area of the park's Rockwood Hall. Several female Lasioglossum oenotherae bees congregated on each of the plant's blossoms. Many of them entered flowers that had not yet opened, in order to gather pollen directly from the closed buds. Anecdotal information suggests that this behavior is typical of this species. Early in the season, females may appear in the evening, but thereafter they tend to be found pollinating evening primrose only in the mornings.
QUEBEC LASIOGLOSSUM. The female bee shown at second right is a Quebec Lasioglossum (Lasioglossum quebecense). This bee belongs to the subgenus Sphecodogastra.
This bee is barely 1/4" long and is dark with faint white stripes banding its abdomen. Its head and thorax appear matte-black to the naked eye. Male Lasioglossum quebecense sweat bees have partially yellow faces and legs and sometimes sport red abdomens instead of black ones.
The above entry in this guide explains that striped Halictus and Lasioglossum sweat bees can be distinguished because on the latter, the pale hairs banding bees' abdomens appear on the inner edges of the abdominal segments. Lasioglossum quebecense are an exception to this rule. As shown in the photo strip below right, on the Quebec Lasioglossum, pale hairs band both the top and bottom of each striped abdominal segment.
Quebec Lasioglossum are pollinators of cranberries, cucumbers and cherries, as well as a vast array of flowering native and garden plants. The bee pictured here appeared in May in the park, nectaring on the woodland ephemeral known as spring beauty.
Sweat bees of the Lasioglossum subgenus Sphecodastra favor sandy, stony areas as nest sites. They produce one generation per year: females build nests consisting of a cluster of 12 to 20 cells constructed close to the soil surface. The bee's offspring hatch about 45 days later. After mating, the males die off, and the females dig deep tunnels in which to hibernate over the winter. In the spring, the female bees lay eggs and the cycle recommences.
Lasioglossum Subgenus Evylaeus sensu lato - 1/5" (very small)
A male Leathery Lasioglossum (Lasioglossum coriaceum)
(Subgenus Lasiglossum) - 1/2"
PHOTO CREDITS: All photos and text © Copyright 2014-2017 Paula Sharp and Ross Eatman, unless otherwise noted. All rights reserved. If you wish to use any of the photographs here for educational or other purposes, please read permissions page.
REFERENCES: For a comprehensive list of references used in compiling this guide, click here: