CUCKOO BEES:  Triepeolus, Epeolus, Sphecodes, Stelis and Nomada Bees

CUCKOO BEES:   The small universe in which wild bees live is a delicate and complex ecosystem.  This ecosystem contains, among other features, predatory bees that have evolved over time inextricably linked to the species on which they prey.  Examples are Triepeolus, Epeolus, Sphecodes, Stelis and Nomada cuckoo bees.

 

Although it is tempting to describe cuckoo bees as the no-good cradle-robbing burglars of the wild bee world, entomologists caution against ascribing human traits to invertebrates.  Suffice it to say that female cuckoo bees enter the underground nests of other bees to lay eggs.  Sometimes, the cuckoos devour the eggs of the host bees that built the nests.  More commonly, the cuckoos depart the nests, leaving behind both their own eggs and their host's.  When the eggs hatch, the cuckoo larvae kill off the host bee's larvae and feed on pollen and nectar the host parent deposited in her brood cells for her own offspring.  In the world of entomology, such a cuckoo bee is called a cleptoparasite.

Cuckoo bees do not gather pollen from flowers, because they obtain it instead by plundering other bees' nests.  As a result, female cuckoo bees do not have scopae, or pollen-collecting hairs. To the naked eye, cuckoo bees often appear hairless and sleek-bodied like wasps.  Cuckoos sometimes have spade-shaped abdomens or other traits that allow them to dig into other bees' nests, and cuckoos generally act differently than their hosts -- many cuckoos spend much of their time skulking around on the ground, looking for their hosts' nests, rather than visiting flowers.

 

Cuckoo bees do, however, drink nectar from flowers.  They often gather on the very blossoming plants that their hosts prefer.  Each cuckoo species tends to target a particular bee species or group.  Thus, Triepeolus and Epeolus bees target long-horned bees; Sphecodes cuckoos tend to prey on sweat bees; Stelis louisae cuckoos parasitize the nests of resin bees; and Nomada cuckoos usually pilfer stores from the brood cells of Andrena mining bees.

Many cuckoo bees choose their hosts from within their own tribe or even genus.  Cuckoo leafcutters, for example, belong to the same bee tribe as the leafcutter bees on which they prey.  Such cuckoos are shown on the leafcutter page of this guide, because they so closely resemble their hosts that one might be mistaken for the other.  Fuzzy cuckoo bumblebees belong to the same genus Bombus as the bumblebees whose colonies the cuckoos invade and conquer.

ID GUIDE TO WILD BEES - NEW YORK

Triepeolus remigatus Cuckoo Bee
Triepeolus remigatus

1/2" (medium-sized)

Triepeolus cuckoo bees invade the nests of long-horned bees and deposit eggs in brood cells intended for long-horned bee eggs. When the Triepeolus young hatch, they kill off the long-horned larvae and feed on the pollen stores left for them by the host bee parent.

As is true of predators generally, Triepeolus bees are less common than the bees they prey on.  Despite their striking appearance, they may be hard to discover, since they have no nests or homes of their own.  Thus, they do not form colonies or aggregations; when sighted, they are usually alone, sipping nectar from a flower, or you may find them on the ground, stalking the long-horned bee world, looking for a good nest to invade.

 

There are approximately 13 species of Triepeolus cuckoo bees in New York State.  ​The species shown at right, Triepeolus remigatus, preys on hoary squash bees (Peponapis pruinosa), a kind of long-horned bee prevalent in Stone Barns' squash beds.  Triepeolus remigatus cuckoo bees have also been recorded preying on large squash bees (Xenoglossa strenua); Centris bees; and Dieunomia heteropoda sweat bees.

Female Triepeolus remigatus cuckoos do not collect pollen from flowers. They do, however, drink nectar from a variety of plants, among them squash and melon flowers, ironweed, mountain mint, catmint, clover, bee balm and various composite flowers of the aster family.

Triepeolus remigatus cuckoos frequent the cut-flower fields and bee gardens of Stone Barns in middle and late July, when squash flowers are in full bloom and squash bees appear in large numbers to pollinate them.  Triepeolus remigatus cuckoo bees at Stone Barns are most often found nectaring on blue cornflowers, orange cosmos and sunflowers.  These bees appear occasionally in the Visitor Garden of Rockefeller State Park Preserve, feeding on coreopsis. 

Identification Information:   Most New York Triepeolus species have striking black-and-white stripes on their abdomens and black-and-white patterns on their thoraxes. The white markings on these bees are formed by short, appressed hairs.  ​The species shown here, Triepeolus remigatus, has a distinctive black anchor-shape on its back, as shown in the photo at right.  ("Remigatus" is Latin for "having oars," a possible reference to the anchor-shape, which might alternately be viewed as two joined oars.)  

 

Because Triepeolus remigatus females do not collect pollen, they lack scopal hairs on their legs and thus closely resemble their male counterparts.  As is true of female bees generally, female Triepeolus remigatus bees differ from males in having 12 antennae segments instead of 13 and 6 abdominal segments instead of 7.  The pattern on the abdomen of the female Triepeolus remigatus thus differs somewhat from that of the male bee, as shown in the photo strip at right.

The  wings of the Triepeolus remigatus cuckoo are transparent dark brown.  The bee's eyes are dark gray.  Its head and antennae are black; in New York specimens, the antennae may have reddish basal segments.  In the Southwest, parts of the bee's head and thorax may be reddish as well.  In the Northeast, the legs of Triepeolus remigatus cuckoos are black, sometimes with dark-brown lower segments.  In the southwestern United States, the legs may be reddish.  

Triepeolus donatus Cuckoo Bee *

Triepeolus donatus
2/5 - 1/2" 
 (medium-sized)

* not yet documented within RSPP 

This species of Triepeolus has not yet been found in the park or Stone Barns.  It has appeared, however, in a power line easement only a few miles away, and is included in this guide as a second example of the genus Triepeolus, in the hope that this species might be identified in the park in the future.

Triepeolus donatus cuckoo bees are cleptoparasites of thistle long-horned bees (Melissodes desponsus), which are locally common in the hardscabble areas where thistles thrive. The power line easement where this bee was discovered is a strip of mown property with hard-packed soil mixed with gravel, overgrown with a mixture of tough native flowers and invasives --  thistles, ironweed, goldenrod, knapweed and toad flax.  Thistle long-horned bees (shown in the photo strip at right) abound in this area.

The bee shown here was found feeding on thistles and knapweed. Triepeolus donatus cuckoos also have been recorded drinking nectar from a variety of other flowering plants, among them Joe Pye weed, knotweed, beggar's ticks, coreopsis, sunflowers, black-eyed Susans, verbena and asters.

 

Triepeolus donatus cuckoo bees once were believed to be cleptoparasites principally of the mallow bee, Melitoma taurea, which is found in the southeastern United States.  Bug guide.net, however, notes that entomologist John S. Ascher recorded in 2004 that Triepeolus donatus cuckoos parasitize thistle long-horned bees as well.  The cuckoos enter the long-horned bees' brood cells by slitting holes in them and then laying eggs in their hosts' nests.

Identification information.  Unlike the Triepeolus remigatus cuckoo bee, the Triepeolus donatus has striking green eyes and lacks an anchor-shaped design on its thorax. The pale hairs that form designs on the bee's thorax and abdomen are white to light gray.

 

The abdomen of the Triepeolus donatus cuckoo is banded with pale hairs.  The bee's thorax sports a design common to many Triepeolus  species -- two short parallel lines of pale hairs that run perpendicular to a collar of white hairs at the front end of the thorax.  (On the weather-beaten specimen shown here, the design is worn; it is more prominent on younger bees.)  On Triepeolus donatus cuckoos, the two lines do not quite touch the white collar; this minute trait is used to distinguish this species from other Triepeolus species, on which the lines connect with the collar. 

 

​TAXONOMY 

Triepeolus cuckoo bees are closely related to bees of the Epeolus genus featured below.  Bees of both genera are wasplike in appearance; have crisply-defined markings; and have abdominal hairs that are short and appressed.  Both Epeolus and Triepeolus cuckoos belong to the tribe Epeolini of the cuckoo bee family Nomadinae.  According to Wilson & Carril, authors of The Bees in Your Backyard, the name Epeolus “likely means ‘without a tail,'” a possible reference to minute attributes of the bees’ abdomens.  (The prefix “Tri” of Triepolus is an obscure reference to the tri-partite mouth structure of the Triepeolus bee and its general resemblance to Epeolus bees.)

Family:  Apidae
Subfamily:   Nomadinae

Tribe:  Epeolini

Genus:  Triepeolus

Subgenus:  none
Species:  
Triepeolus remigatus,  Triepeolus donatus

A male Tripeolus remigatus cuckoo bee

The Tripeolus remigatus cuckoo bee has a distinctive black anchor-shape on its thorax

The Tripeolus donatus cuckoo bee has green eyes and lacks an anchor shape on its thorax.

All photos (c) 2014 - 2017 Sharp-Eatman Nature Photography

Two-banded Epeolus Cuckoo Bee

Epeolus bifasciatus
1/4" - 1/3" (small to medium-small)

Epeolus bees are a variety of cuckoo bee that parasitizes the nests of cellophane bees of the genus Colletes.  Cellophane bees protect their nests from moisture by lining their brood- cell walls with a plastic-like substance.  The female Epeolus bee has spikes on the ends of her abdomen that allow her to break through the walls' plastic seal in order to penetrate cellophane bee nests. The Epeolus bee then exudes a glue-like substance, which she uses to append her own eggs to cellophane bee brood-cell walls.  When the Epeolus larvae hatch, they feed on the pollen provisions left by the mother cellophane bee for her offspring.

There are about 100 species of Epeolus bees worldwide; 9 reside in New York State alone. The species shown here is the two-banded Epeolus cuckoo bee (Epeolus bifasciatus).  Entomologist Charles Robertson noted in his 1926 publication, "Phenology of Inquiline and Nest-malting Bees," that he believed Epeolus bifasciatus cuckoos targeted the nests of broad-footed cellophane bees (Colletes latitarsis).  (These tomatillo pollinators are shown on the cellophane bee page of this guide.)

Epeolus bifasciatus bees feed on the nectar of an array of flowers, including, for example, black-eyed Susans, wild carrot, melilot, mountain mint, milkweed, thistles, catmint, goldenrod and coreopsis. The bee shown here was found foraging on a variety of black-eyed Susan in Stone Barns’ bee garden during the last week of July, 2017.  This is the single specimen of a two-banded Epeolus found at Stone Barns, although broad-footed cellophane bees are well-established at this location.

As noted in the above guide entry on Triepeolus remigatus cuckoo bees, Epeolus cuckoo bees are closely related to bees of the Triepeolus cuckoo bee genus.  Both Epeolus and Triepeolus cuckoos are cleptoparasites belonging to the tribe Epeolini of the cuckoo bee family Nomadinae.  

Identification Information:  All 9 species of Epeolus cuckoos found in New York State are dark, with black abdomens that are boldly striped with pale bands of dense, short hairs. Several have red legs or red markings on their thoraxes or faces.  New York Epeolus species often can be told apart by the positioning and form of their abdominal hair bands.

The Epeolus bifasciatus cuckoo has two distinctive bands of short, pale-yellow hairs on its primarily black abdomen.  These bands are located toward the base of the first abdominal segment (T-1) and toward the outer edge of the second abdominal segment (T-2).  The bee’s hind abdominal segments fold into one another in a plate-like way, a little like the body of a shrimp, as shown in the photographs at right.  The bee’s wings are distinctively dark.

The two-banded Epeolus bee’s head and thorax are primarily black and heavily pitted.  The pronotal collar lining the front of the bee’s thorax is pale yellow.  The bee also has various parts that are colored a striking dark red.  The tubercles (the two nodes at the front of the thorax) are a dark rust-red, as are the tegulae (where the wing attaches). The axillae and scutellum (at the back of the bee’s thorax) are also a dark-rust color.  The basal portions of the bee’s antennae (the scape, pedicel and F-1 and F-2) are reddish; the remaining antennal segments are black. These details are highlighted in the photo strip at right.

The individual bee shown here is somewhat unusual:  according to the Discover Life Database, Epeolus bifasciatus bees in the northeastern and midwestern United States tend to have black legs, and a black labrum, clypeus, propodeum (back portion of thorax) and pygidium (abdominal tip). Conversely, these features tend to be red on Epeolus bifasciatus cuckoos found in the southeast and reddish-orange on those of the Southwest.  Nonetheless, this New York bee specimen has legs that are primarily a dark reddish-orange; reddish jaws; and a narrow reddish stripe on its face, located just above the mandibles.

Male and female bees of this species closely resemble each other.  The bee shown here is a male.

​TAXONOMY  -  Epeolus bifasciatus

Family:  Apidae
Subfamily:   Nomadinae

Tribe:  Epeolini

Genus:  Epeolus

Subgenus:  none

Species:  Epeolus bifasciatus

A Male Two-Banded Epeolus Cuckoo Bee

All photos (c) 2014 - 2017 Sharp-Eatman Nature Photography

Sphecodes Cuckoo Bee

1/5- 2/5" (very small to moderate-sized)

Johnson's Sphecodes

Sphecodes johnsonii

Hercules Sphecodes

Sphecodes heraclei heraclei

Buttercup Sphecodes 

Sphecodes ranunculi

Mandibular Sphecodes* 

Sphecodes mandibularis
*not yet documented within RSPP

Sphecodes means "like a wasp" in Greek.  Sphecodes bees' slender, relatively hairless bodies  lead many people to mistake them for wasps.  In fact, Sphecodes are solitary bees that are harmless to humans:  they do not swarm or build collective nests the way some aggressive wasps do. 

 

Sphecodes are cleptoparasites that invade the nests of Halictus, Lasioglossum and green metallic sweat bees – and occasionally bees of other genera as well (such as Colletes, Perdita and Andrena mining bees). Sphecodes belong to the same family as Halictus and Lasiglossum sweat bees (Halictidae) but occupy a separate genus (Sphecodes).

Most of the cuckoo bees shown on this guide page 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 their nests to lay eggs. Occasionally, adult Sphecodes bees move into the nests of their hosts and cohabit with them.

Identification:  There are 72 recorded Sphecodes species in the United States and Canada.  In the northeastern United States, Sphecodes bees tend to be slender, with black heads; black thoraxes; and 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.  Identification of individual species is problematic, because many Sphecodes (particularly males) have yet to be systematically documented and catalogued in keys and databases available to the rank-and-file naturalist.

Four species of Sphecodes bees are shown here:  Johnson's Sphecodes, and Hercules Sphecodes, have appeared in the park in late summer, feeding on goldenrod.  The very small Sphecodes mandibularis was found in a railroad access nine miles away during the same period, also feeding on goldenrod.   Sphecodes rununculi is a spring bee that appeared in the park in May, 2017, nectaring on raspberry blossoms.

 

Johnson’s Sphecodes (Sphecodes johnsonii)
has been documented principally in New York and New England, although it has been found in the upper Midwest as well. Both females and males of this species are moderately large -- between 3/10" and 2/5". 

 

Female Johnson's Sphecodes bees have red-tipped black abdomens and black heads and thoraxes. Males are entirely black.  (Sexual dimorphism of this kind is a fairly common trait of Sphecodes cuckoos -- many females have abdomens that are red or partially red, while their male counterparts have black abdomens.)  Both male and female Johnson's Sphecodes bees have roughly-textured thoraxes and relatively short antennae on which the first flagellomere (the third antenna segment from the bottom) is broader than it is long.

The male Johnson's Sphecodes was officially documented only recently, during a 2014 survey conducted on Gardiners Island in Suffolk County, New York, by entomologist John S. Ascher, biologist Sarah Kornbluth and island resident Robert G. Goelet.  The male bee shown here was found in the park in September, 2016.

Johnson's Sphecodes bees favor goldenrod, which flowers during this period.  These bees also have been documented feeding on wild carrot and buckwheat.  When not foraging for nectar, Johnson's Sphecodes bees can be observed flying low over the ground, looking for the nests of host bees.

Hercules Sphecodes (Sphecodes heraclei) appears in the park in early fall, feeding on goldenrod.  This bee parasitizes the nests of Halictid sweat bees.  The male Hercules Sphecodes has distinctive scalloped antennae and a circular bump on its vertex (the top of its head), behind the bee’s ocelli (small eyes).  This last trait is diagnostic of the species.  The male bee shown here was a little more than 1/3” long.  

​Hercules Sphecodes have been documented feeding on nectar of such plants as goldenrod, heather, winged sumac, New Jersey tea, black-eyed Susans and wild carrot.  The male bee featured here was spied nectaring on goldenrod along the edge of Rockefeller Park's Swan Lake in mid-September, 2016.  More Hercules Sphecodes were discovered in the same area in mid-September, 2017.

There are two recognized subspecies of the Hercules Sphecodes bee.  The one shown here is Sphecodes heraclei heraclei.  Males of this subspecies are entirely black. Females have black heads and thoraxes, and predominantly red abdomens with black terminal segments. Males of the second subspecies, Sphecodes ignitus, have abdomens whose upper portions are red.  Females have red thoraxes and black-tipped red abdomens.

The buttercup Sphecodes (Sphecodes ranunculi) shown at third right, is a slender bee, a little more than 1/3 inch long (9 mm).  Both males and females of this species have black heads and thoraxes, and narrow abdomens that are entirely red.  These bees are difficult to distinguish with the naked eye from several other Sphecodes species with red abdomens (among them S. clematidis, S. hydrangea, S. prosphorus, and S. aroniae).  As shown in the photo strip at bottom right, differences among species hinge on minute characteristics such as the length of the bee's first antennae segments and the width of its leg segments.  

 

Sphecodes ranunculi has been documented foraging on predominantly spring-blossoming plants such as American holly; members of the apple, plum and pear families; dewberry and wineberry; blueberry; red osier dogwood; black chokecherry; gooseberry; winter cress; and wild roses.  Despite its name, ranunculi (Latin for "of the buttercup") , this bee has not been observed feeding in the park on buttercups, which emerge in May in our area. The bee shown here was found in mid-May, 2017, nectaring on wild raspberries cultivated in hilltop fields at Stone Barns Center for Food and Agriculture.

The mandibular Sphecodes (Sphecodes mandibularis) is the smallest of the cuckoo bees shown here -- the male bee shown at fourth right is barely 1/5" long.  Females of this species have entirely red abdomens.  Males have black with partly red abdomens:  the male's first three segments are part-red and part-black; the remaining four are entirely black.  Both males and females have black heads, thoraxes, heads, legs and antennae.

Very little literature is readily available on this minute species. It was first documented by the entomologist Ezra Townsend Cresson in 1872.  The Discover Life database notes that mandibular Sphecodes feed on goldenrod, sumac, ox-eye daisies, narrow-leaf spiraea, wild hydrangea, members of the rose family and caneberry blossoms and the invasive Japanese knotweed.

 

The bee shown here was found in mid-September, nectaring on goldenrod in a sandy area bordered by a railroad access and a swamp, situated 9 miles north of Rockefeller State Park Preserve.  This area was heavily frequented by eight-spotted Perdita mining bees, ligated sweat bees and various Lasioglossum sweat bees. This Sphecodes species has not yet appeared in the park.

Distinguishing Sphecodes bees from sweat bees:  Sphecodes cuckoo bees can be mistaken easily for small, dark sweat bees of the family Halictidae.   Sphecodes bees, however, differ from sweat bees in a few general respects:   (1) Sphecodes bees lack hairbands on their abdomens, a trait shared by many Halictus and Lasioglossum sweat bees. (2) As is true of other female cleptoparasites shown on this guide page, 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. (3) Sphecodes males do not have yellow on the clypeus (the face-part above the jaws, yellow in many sweat bee males).  (4) 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 bottom right) is strongly arched, and the bees’ wing veins generally are well-defined.

TAXONOMY  -  Johnson's Sphecodes Cuckoo Bees

Family:  Halictidae

Subfamily:  Halictinae

Tribe:  Halictini

Genus:  Sphecodes

Species:  Sphecodes johnsonii
                Sphecodes heraclei
                Sphecodes mandibularis
                Sphecodes ranunculi

A Johnson's Sphecodes Cuckoo Bee (female) - 1/3"

Johnson's Sphecodes

A Johnson's Sphecodes Cuckoo Bee  (male) - 2/5"

A Hercules Sphecodes Cuckoo Bee  (male) - .35"

Hercules Sphecodes

A Buttercup Sphecodes  (male) - .35"

Buttercup Sphecodes 

A Mandibular Sphecodes  (male) -  1/5"

Mandibular Sphecodes 

Stelis Louisae Cuckoo Bee

Stelis louisae (Subgenus Dolichostelis)

1/3" (small to medium-sized)

Both Stelis cuckoos and the bees on which they prey belong to the bee family Megachilidae.  The species Stelis louisae specifically targets the bellflower resin bee  and other members of its subgenus. 

 

Stelis louisae cuckoos steal into resin bee nests after removing the resin seals those bees cement onto the entrances of their egg chambers. Once inside the nests, Stelis louisae cuckoos destroy the host eggs or larvae and lay their own eggs in the hijacked chambers.  According to entomologist Charles D. Michener's The Bees of the World, when Stelis louisae cuckoo bees leave their hosts'  nests, the cuckoos replace the entrances' resin seals.  Upon hatching, the cuckoo larvae devour provisions left by the mother resin bee for her own slaughtered offspring.

 

Like the other cuckoo bees on this page, Stelis louisae cuckoos do not gather pollen and are not endowed with scopal brushes for carrying pollen.  The bees do, however, sip nectar, and can be found foraging on sunflowers, wild indigo, mountain mint, fleabane,  goldenrod and other flowers.  The bee shown here was feeding on mountain mint and Joe Pye weed.

 

This cuckoo bee belongs to the family Megachilidae and the subfamily Megachilinae, which also include leafcutters and resin bees.  Stellis louisae cuckoos, however, belong to a separate tribe (Anthidiini) and subgenus (Dolichostelis), and do not gather leaves or resin for making nests in the manner of leafcutter and resin bees. 

 

Identification information:  Bees of the subgenus Dolichostelis have an elongate (slender) shape, and are black with pale or yellow markings and coarse punctures on their bodies.  Stelis louisae bees specifically have yellow face markings edging their compound eyes; yellow lines tracing the rims of their thoraxes; and yellow stripes banding their abdomens.  Stelis louisae bees' legs are reddish and their wings transparent brown.  The  reddish coloration of the bees' legs is less pronounced in New York than in the bees' southern range.

 

The Stelis louisae cuckoo can be distinguished from other cuckoo bees of its subgenera by the broken yellow line on its second abdominal segment, as shown in the photo strip at right. The yellow markings on Stelis louisae also tend to have an orangish tinge.  The bee shown in the photographs here is a female. Both females and males have broad yellow stripes along the inner rims of their compound eyes.  The male additionally has a thick yellow mark on the bottom of its face that joins the two stripes. 

 

 

TAXONOMY  -  STELIS LOUISAE CUCKOOS

Family:  Megachilidae

Subfamily:  Megachilinae

Tribe:  Anthidiini

Genus:  Stelis

Subgenus: Dolichostelis

Species:  Stelis Louisae

All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography

Nomad Bee

1/4" - 7/16" (small to medium-sized)

Neighborly Nomad Bee
Nomada vicina

 

Beautiful Nomad Bee
Nomada bella

Spotted Nomad Bee

Nomada maculata

 

Slender Nomad Bee

Nomada gracilis

Yellow Nomad Bee

Nomada luteoloides

 

Articulated Nomad Bee
Nomada articulata

Nomad bees have the flashy appearance of custom-detailed race cars.  They have sleek bodies, often adorned with well-defined stripes and crisp markings, and are easily mistaken for wasps.  These cuckoo bees emerge in early spring in Rockefeller Park and Stone Barns and disappear at the beginning of summer.  They re-emerge again months later, when cooler September weather sets in. 


Like other cuckoo bees on this page, the nomad is a  variety of cleptoparasite -- that is, to feed their young, nomad bees steal resources from other bees.  Nomad bees lay eggs in the nests of ground-nesting bees -- in our area, usually Andrena mining bees.  When the nomad eggs hatch in Andrena nests, the nomad larvae – which have large, sickle-like mouth parts -- kill off the Andrena larvae and eat the provisions stored in the nest by the Andrena mother.  According to The Xerces Society Guide to Attracting Native Pollinators, male nomad bees can imitate the scent of Andrenas and have the capacity to transfer this scent to female nomads during mating.  This allows the female bees to sneak more easily into Andrena nests to hijack their food supplies. 

Some nomad bees are generalists that parasitize the nests of multiple Andrena species.  Other nomads target specific Andrena species.  The neighborly nomad bee, for example, targets the nests of hairy-banded mining bees (Andrena hirticincta). The spotted nomad bee (Nomada maculata), preys on neighborly mining bees (Andrena vicina).  The beautiful nomad bee (Nomada bella) is a cleptoparasite of Andrena imitatrix.  Nomad bees also exist that prey on Agapostemon, Halictus, and Lasioglossum sweat bees.  Some nomad species target  Colletes bees, long-horned bees in the genus Eucera or bees in the genus  Melitta.

Nomad bees drink nectar from flowers, but do not collect pollen, because their cleptoparasitic lifestyle renders provisioning their own nests with pollen unnecessary. Nomad bees in our area feed on a variety of flowering trees and wildflowers.  The bees shown here were found on willow, claytonia, bloodroot, fleabane, wild blackberries,  marsh marigold, winter cress, wild geranium, millkweed, goldenrod and the flowering fragrant herb valerian. 

 

Although nomad bees are solitary, it is not unusual to see several within close range of one another in the park, flying low over the ground in search of Andrena bees.  And generally, when you spot a nomad bee, you soon will find Andrenas in the vicinity.  At times, however, you may spy many nomad bees patrolling an area but not glimpse a single Andrena  -- this is because the Andrenas are hidden in their nests under leaflitter, debris and dirt.  The nomad bees have no nests of their own:  they are scouting around for Andrena nests to steal into.

Species Identification Information:   Approximately 50 species of nomad bees are found in New York State.   Most nomad bees in our area have striking red or reddish-brown antennae; red or green eyes; reddish legs; slender wasp-like bodies; and red or black abdomens with yellow markings. Many have yellow-and-red or yellow-and-black markings on their heads and thoraxes.  General coloration varies from one type of  nomad bee to another and can be used in part to help identify  species.  Female nomad bees have specialized hair patches on the tips of their abdomens.  The pygidial plate (abdomen tip) of male nomad bees is pronounced and often notched.

​​The six varieties shown here reveal the remarkable species variation among nomad bees.  Although these six share a similar general shape and appearance, they vary greatly in coloration.  The first five belong to the species group known as red-horned nomad bees (ruficornis). The sixth, Nomada articulata, belongs to the closely related species group erigeronis.

The neighborly nomad bee (Nomada vicina), shown top right, is a late-summer nomad bee.  It appears in  early and mid-September, when goldenrod is in full bloom -- during the same weeks when the cukoo's host, the hairy-banded Andrena , emerges.  The neighborly nomad bee shown here is predominantly black, with a black-and-yellow banded abdomen, dark antennae, reddish-brown eyes and red-legs.  This bee is a male.  Females of the same species appear quite different -- they are predominantly red, with red legs and -- as the genus name red-horned nomad bee implies -- the bees have red antennae as well.  This trait is common to most nomad bees in the ruficornis species group.  Both male and female neighborly nomad bees have red tegulae (where the wing attaches) and red turbercules on the rear third of the thorax. Males also have yellow markings on their faces and yellow scapes (the bottom segments of each antennae). The bee shown here was found drinking nectar from goldenrod -- the preferred plant of hairy-banded  Andrenas as well.

The beautiful nomad bee (Nomada bella), shown second right,  is one of the very earliest wild bees to emerge in spring in our area. The male bee shown here appeared during the first week of April, 2017, in woodlands where no plants other than willow trees were visibly in bloom. The bee was flying low to the ground over leaf-litter, presumably looking for signs of females of its species. Males of this variety of red-horned nomad bee are distinguished by broad yellow abdominal stripes and by an almost entirely black thorax without the colorful tubercules  sported by typical nomad bees of our area.   Beautiful nomad bees also have distinctive silvery hair on their faces (on the labrum and clypeus) and green eyes.  The thoraxes of male bees are densely covered with whitish hair. Beautiful nomad bees, as noted above, parasitize the nests of Andrena imitatrix mining bees.  These nomads feed on willow blossoms and on dandelions. 

 

The female spotted nomad Bee (Nomada maculata) at third right is carnelian-red with distinctive gold markings on its red abdomen, red antennae and red eyes.  Males of this species look quite different -- they have predominantly black heads and thoraxes with red tubercules; abdomens with red, yellow and black markings; red-and-black legs; and dark red antennae.  This nomad bee emerges between March and June in our area and preys specifically on the mining bee species  Andrena vicina.  This cuckoo can be found nectaring on dandelions, winter cress, willow, spurge, winterberry, shadbush, common milkweed and blueberry and apple blossoms.

The fourth bee at right, a Slender Nomad bee (Nomada gracilis), is predominantly red with a black, red and yellow abdomen.  It has red antennae and red eyes. This is a small nomad bee that emerges as early as March, feeding on willow tree blossoms.  We could find no specific information regarding species targeted by this nomad bee.  We have seen slender nomad bees digging into the nests of unknown hosts in the gardens of Stone Barns during the spring (as shown in the photograph at right).  This nomad bee is discussed in earlier literature under its former name, Nomada inepta.
 

The fifth bee at right, the Yellow Nomad Bee (Nomada luteoloides), is the most common spring nomad bee in the preserve. This bee has a  black face with prominent yellow mask-like markings; a black thorax with yellow tubercules and markings; a striped black-and-yellow-abdomen; yellow legs; greenish eyes; and dark reddish antennae.  Yellow nomad bees appear in April and May and nectar on willow, apple, blueberry, trout lily, plantain and garlic mustard.  Entomologist John S. Ascher notes at bugguide.net that nomads are cleptoparasites of Andrena of the subgenus Melandrena, which includes, for example, Dunning's and Carlin's Andrenas, and neighborly, confederate and plum mining bees (shown on the Andrena page of this guide).

The sixth bee is a male Articulated Nomad Bee (Nomada articulata), a member of the species group Erigeronis.  This femlae of this species is almost entirely red.  As shown in the photo strip at right, the male bee looks quite different -- it has a mostly black head and thorax; red eyes; dark-red antennae; and an abdomen that is red with yellow markings. In our area, this bee is seen most commonly in June, when it feeds on a fairly broad range of plants, including, among others,  willow, fleabane, ox-eye daisies, cinquefoil and strawberries.  This is the single nomad species shown here that does not target Andrenas. According to entomologist John S. Ascher, via bugguide.net, the articulated nomad bee parasitizes the nests of green metallic sweat bees belonging to the genus Agapostemon.

When identifying individual species of nomad bees, entomologists consider a number of factors, among them size; general coloration; small visual details not readily observed by the naked eye;  and the region and time of year in which the bees emerge.

TAXONOMY  -  RED-HORNED NOMAD BEES

Family:  Apidae

Subfamily:  Nomadinae

Tribe: Nomadini

Genus:  Nomada

Species Group:  Ruficornis
Species:  Nomada  vicina, Nomada bella, Nomada gracilis,
               Nomada luteoloides, Nomada maculata

TAXONOMY  -  NOMADA ARTICULATA

Family:  Apidae

Subfamily:  Nomadinae

Tribe: Nomadini

Genus:  Nomada

Species Group:  Erigeronis
Species:  Nomada articulata

Neighborly Nomad Bee  (Nomada vicina)  (male)  - 1/ 3"

Beautiful Nomad Bee  (Nomada  bella)  (male)  - 1/ 4"

Spotted Nomad Bee  (Nomada maculata)  (female)  - 1/ 4"

Slender Nomad Bee  (Nomada gracilis)  (female)  -  3/10"

Yellow Nomad Bee  (Nomada luteoloides)  (male)  -  1/2"

Articulated Nomad Bee (Nomada articulata) (female) - 1/3"

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REFERENCES:  For a comprehensive list of references used in compiling this guide, click here:

 8-23-15