SHARP-EATMAN
NATURE
PHOTOGRAPHY
ID GUIDE TO WILD BEES
OF THE NATIONAL BUTTERFLY CENTER
Mission, Texas
ANTHOPHORULA & EXOMALOPSIS
Exomalopsis Species of the National Butterfly Center
THE BEE TRIBE EXOMOLOPSINI
Genus Anthophorula
Genus Exomolopsis
If you live in more northern parts of the United States, you may never have had the pleasure of encountering an Exomalopsis. These are beautiful bees. They are uniquely colorful: their legs may be rust-orange or multi-colored, and their eyes are brilliant green or blue-gray. Their abdomens are dark and ringed with pale hairs. Females have luxuriant scopal hairs on their hind legs evocative of the groomed fur of champion show dogs. Males tend to have very long antennae, and partly-yellow jaws. Exomalopsis are frequent visitors to the National Butterfly Center during the spring and fall.
These bees deserve a name that reflects their elegant beauty. Nonetheless, they instead bear the hefty label “Exomalopsis”. In Greek, Exomalopsis literally means “not bad-looking”. (Exo= without; mal=bad; opsis=appearance). Thus, loosely translated, one might call the Exomalopsis the "not-so-ugly bee".
Anthophorula is a close cousin of Exomalopsis: together, these two genera comprise the bee tribe Exomalopsini. Anthophorula is a genus of hairy bees that often have dark abdomens banded with pale hairs. Like female Exomalopsis, female Anthophorula have lush scopal hairs on their back legs. Males sport long antennae and often have yellow facial markings.
Anthophorula tend to run smaller than most Exomalopsis. (In Greek, the name Anthophorula means "little flower bearer".) Anthophorula tend to appear at the National Butterfly Center in early April, shortly before prickly pear cactus blooms in Hidalgo and Starr Counties.
Anthophorula vs. Exomalopsis
Exomalopsis and Anthophorula share a trait that the legendary entomologist, Charles D. Michener, noted was common to all members of the tribe Exomalopsini: they have a long row of erect, well-separated hairs lining the inner side of each compound eye orbit.
Other minute differences, shown in the accompanying photo strip, separate these two genera. According to Michener: (1) The clypeus (the face part above the jaws) of the male Exomalopsis is always dark. The Anthophorula male’s clypeus, however, may be yellow. (2) The hind knee plates are larger on Exomalopsis males than on Anthophorula males. (2) The stigma of the forewing is proportionately larger in Exomalopsis; in Anthophorula, the stigma is less than half the length of the marginal cell, with some exceptions. (A few species of Anthophorula also have two marginal cells instead of three.)
Exomalopsis and Anthophorula behavior
Both Exomalopsis and Anthophorula are solitary and nest in the ground. In both genera, each female bee provisions her own individual nest, digging out oval egg chambers and coating them with a thin waterproof lining. Females store pollen for offspring on a “foot,” a small mound of dirt slightly elevated from the nest floor, to protect against moisture.
Despite their solitary status, Exomalopsis and Anthophorula may live communally, with several females inhabiting a single burrow that shares a common entrance. Within at least one Exomalopsis species, E. solani, females even aid one another in storing pollen. Such behavior is relatively rare among bees.
Pollinator plants
Many Exomalopsis are pollinator generalists. At the NBC, Exomalopsis are frequent visitors to an array of wild and garden flowers, most notably crucita, croton, mallows and small-flowered Asteraceae.
Anthophorula are also often generalist pollinators; some, however, specialize in pollinating such plants as gumweed and leafy spurge, while others exhibit a preference for plants in the aster and buckwheat families. The Anthophorula compactula shown below has appeared nearly exclusively on prickly pear cactus, twisted rib cactus and red prickly poppy at the National Butterfly Center and abutting areas. Nonetheless, this species is known to visit a broad spectrum of plants.
Some Exomalopsis and Anthophorula are capable of vibratile ("buzz") pollination and are thus good pollinators of crops in the tomato family (Solanaceae). Plants in this family, which includes peppers, eggplants and potatoes, require this special pollination method (in which the bee vibrates its wing muscles to shake pollen loose from a flower's anthers). This capability is an important trait, because honey bees cannot buzz pollinate and thus cannot be relied on to pollinate such crops. At the National Butterfly Center, Exomalopsis can be observed visiting the wildflower silver-leaf nightshade, a member of the Solonaceae family.
Species range and Identification information:
Both Exomalopsis and Anthophorula are found only in the Western Hemisphere. Ten species of Exomalopsis inhabit the United States. At least 7 have been documented previously in Texas: Exomalopsis analis, E. birkmanni, E. mellipes, E. snowi, E. solani, E. solidagnis and E. tibialis. All but the last of these appear in the Valley.
Little photographic documentation of Exomalopsis and Anthophorula species is widely available, and thus identifying them can be challenging for naturalists and pollinator enthusiasts. The Exomalopsis and Anthophorula species shown here were identified through the aid of Texas bee expert John L. Neff, President of the Central Texas Melittological Institute. Explanations of distinguishing traits of individual Exomalopsis and Anthophorula species found at the NBC are given below, together with detailed photographs.
A male Anthophorula
A female Exomalopsis, showing the bushy scopal hairs typical of the genus
ANTHOPHORULA vs. EXOMALOPSIS
This is an Exomalopsis. Note the luxuriant scopal hairs on the bee's hind legs. The bee also has pale hairs bands ringing a dark abdomen. These traits are common to many members of the tribe Exomalopsini, which includes both Exomalopsis and Anthophorula bees. The Exomalopsis shown here is 10 mm (2/5 in.) long.
This is an Anthophorula: it is a mere 5.5 mm (1/5 in.) long. Anthophorula tend to be smaller than Exomalopsis.
View of vertex and thorax of an Exomalopsis. The thoraxes of both Exomalopsis and Anthophorula are often shiny and relatively hairless.
This is an Anthophorula. Both Anthophorula and Exomalopsis have short parallel hairs that line the inner edges of their compound eyes.
Face of female Exomalopsis. Both the male and female Exomalopsis have a dark clypeus (the part above the jaws).
By contrast, male Anthophorula, like that shown here, may have yellow clypei.
Leg of a female Exomalopsis
TAXONOMY OF EXOMALOPSINE BEES
Order: Hymenoptera
Family: Apidae
Subfamily: Eucerinae
Tribe: Exomalopsini
Genus: Exomalopsis
Species shown below:
Anthophorula (Anthophorula) compactula
(Compact Anthophorula)
Anthophorula (Anthophorula) completa
(Complete Anthophorula)
Exomalopsis (Exomalopsis) analis
(Ringed Exomalopsis)
Exomalopsis (Exomalopsis) mellipes
(Honey-footed Exomalopsis)
Exomalopsis (Exomalopsis) similis
(Similar Exomalopsis)
Exomalopsis (Phanomalopsis) snowi
(Snow's Exomalopsis)
Exomalopsis (Stilbomalopsis) birkmanni
Birkmann's Exomalopsis)
Exomalopsis (Stilbomalopsis) solani
(Solanum Exomalopsis)
Anthophorula Species of the Lower Rio Grande Valley
Compact anthophorula
Anthophorula (Anthophorula) compactula
Family: Apidae
Size: 4.5 mm-5.5 (male)
6-7 mm (female)
Associated plants
Prickly Pear Cactus
(Opuntia engelmannii)
Twisted-rib cactus
(Thelocactus setispinus)
Plant family: Cactaceae
Red Prickly Poppy
Argemone sanguinea
Plant family: Papaveraceae
When seen:
April - June
NBC (Hidalgo Co.)
Dos Venados Ranch
Rio Grande City, TX (Starr Co.)
This is a male compact Anthophorula.
The male Anthophorula compactula has a yellow clypeus. This is a trait common to many male Anthophorula species. Males of this species have green eyes.
Male bees of the species Anthophorula compactula have distinctive black-and-yellow markings on their antennae scapes (lower antennal segments).
The rear surfaces of the male bee's antennae are striped yellow-and-black.
This is a female compact Anthophorula. Female bees of this species have bright pale-blue eyes. Note that the scopal hairs on the bee's outer hind legs are predominantly pale.
Face of a female compact Anthophorula.
Profile of female bee's head.
This female bee is collecting pollen from the sticky stamens of twisted rib cactus.
A male Anthophorula compactula
A female Anthophorula compactula
A male Anthophorula compactula on the head of a dime
In the Lower Rio Grande Valley, this beautiful small bee emerges in spring. Male Anthophorula compactula appear in early April in Hidalgo and Starr Counties, feeding on Texas prickly pear cactus. Female bees surface about ten days after males. They usually are found collecting pollen from three different plants -- red prickly poppies, Texas prickly pear and twisted rib cactus.
An important distinguishing characteristic of this species is a minute trait relating to the bee's wings: each forewing of the male and female Anthophorurla compactula has only two submarginal cells. This trait aids in distinguishing this species from the similar Anthophorula completa shown below. Other notable traits that help in identifying Anthophorula compactula include: (1) male bees have extensive yellow masks on their lower faces; (2) male bees' antennae are striped black-and-yellow on their hind surfaces; (3) female bees have black scopal hairs, sometimes commingled with reddish -brown hairs, on their lower hind legs.
Complete anthophorula
Anthophorula (Anthophorula) completa
Family: Apidae
Size: 4.5-5.5 mm (male)
6-6.5 mm (female)
Associated plants:
Silver bladderpod
(Physaria argyraea)
Plant family: Brassicaceae
Wrinkled globemallow
(Sphaeralcea hastulata)
Plant family: Malvaceae
When and where seen:
April 17, 2023
Dos Venadas Ranch
Rio Grande City, TX (Starr Co.)
A male Anthophorula completa
The male Anthophorula compactula is a small bee with mostly pale hair on its head, thorax and legs. Its abdomen banded by pale hairs.
The male bee has extensive yellow facial markings, green eyes, and gold-and-black antennae.
Dorsal view of bee
Close-up of vertex and thorax of a male Anthophora completa
A female Anthophorula completa: to the naked eye, females of this species look nearly identical to female Anthophorula. compactula
The female Anthophorula compactula is a small hairy bee with a banded abdomen.
Face of a female Anthophorula completa: the female bee's face is black and covered partly with pale hairs; its antennae are short and golden-brown; and its eyes pale blue.
Dorsal view of bee
A female Anthophorula completa
Anthophorula completa originally was considered a variation of Anthophorula compactula: to the naked eye, females appear nearly identical. Nonetheless, Anthophorula compactula and A. completa can be differentiated easily by examination of their wings under magnification: the forewings of Anthophorula compactula have two submarginal cells, while those of A. completa have three. The wings of both are glassy with brown veins; those of Anthophorula compactula darken toward the tips.
Males of the two species also differ in other ways: the antennal scapes of male Anthophorula compactula are a mottled black-and-yellow, while those of A. completa are predominantly black. In addition, on Anthophora compactula, the rear surface of the flagellum is yellow with black stripes. On Anthophorula completa, the dark areas of the flagellum are large, nearly filling the back surface of each segment. The black areas of the antennae of the male Antophorula completa bell outward, giving the antennae a scalloped look, and the flagella themselves are curved.
Female Anthophorula compactula and Anthophorula completa show only subtle differences from each other, even under magnification (apart from the variation in forewing submarginal cells). On female Anthophorula compactula, the hair on the scutum (front section of the thorax) is mosslike and light-colored; on A. completa, the hair on the scutum is longer and brownish. On Anthophorula completa, the inner hind-leg scopal hairs are dusky and black; on A. compactula. they may be reddish. The female Anthophora compactula may be as large as 7 mm, while the female A. completa tends to run smaller.
Anthophorula completa and Anthophorula compactula have a similar range -- both are found predominantly in the western and southwestern United States. In the Valley, Anthophorula compactula is commonly associated with cacti. Anthophorula completa is more likely to be found on mallows.
Food plants at NBC:
Crucita
(Chromolaena odorata)
Skeleton-leaf goldeneye
Seaside goldenrod
Plant family: Asteraceae
Low croton
(Croton humilis)
Plant family: Euphorbiaceae
Texas ebony
(Ebenopsis ebano)
Plant family: Fabaceae
When found:
June, November
Snow's Exomalopsis
Exomalopsis (Exomalopsis) snowi
Family: Apidae
Size: 8 mm (female); 7 mm (male)
A female Snow's Exomalopsis (Exomalopsis snowi)
On this species, the tegulae (the plates where the bee's wings join its body) and most of the scopal hairs are orange.
The bands of hair on the abdomen of the female Exomalopsis snowi are pale gold: The presence, completeness, color and positioning of such abdominal bands are traits that help distinguish one Exomalopsis species from another. Note that the black portions of the first and second segments are shiny rather than dull and pitted -- this minute trait helps distinguish this species from Exomalopsis mellipes, shown below.
A female Exomalopsis snowi
A male Exomalopsis snowi
A male Snow's Exomalopsis (Exomalopsis snowi)
As is true of male bees generally, male Exomalopsis do not gather pollen and thus lack scopal hairs on their legs.
Male Exomalopsis snowi have thick pale hairs covering their faces.
Honey-footed Exomalopsis
Exomalopsis (Exomalopsis) mellipes
Family: Apidae
Size: 10 mm (female)
8-9 mm (male)
Food plants at NBC:
Crucita
(Chromolaena odorata)
Seaside goldenrod
Romerillo
Plant family: Asteraceae
Prickly Malvastrum
(Malvastrum coromandelianum)
Plant Family: Malvaceae
Cenizo
(Leucophyllum frutescens)
Plant family: Scrophulariaceae
Whitebrush
(Aloysia-gratissima)
Plant Family: Verbenaceae
When found:
June-July, September - November
A female Exomalopsis mellipes
This species is distinguished from other Exomalopsis in part by the colors of its leg hairs and tegulae (the plates where the wing joins the body). Note that some of the outer scopal hairs on the bee's hind legs are orange and dark-brown. The bee's tegulae are orange.
Rear view of the female bee's abbdomen
The male Exomalopsis mellipes has reddish legs, a reddish abdomen and red tegulae (the plates where the wings meet the body). The scapes (lowest segments) of the bee's antennae are red, as is most of the front surface of the rest of each antenna.
The male bee's eyes are green.
Rear view of the male bee's abdomen and hind legs
A female Exomalopsis mellipes
A female Exomalopsis mellipes
A male Exomalopsis mellipes
Ringed Exomalopsis
Exomalopsis analis
Family: Apidae
Size: 8-9 mm (female)
Food plants at NBC:
Crucita
Chromolaena odorata
(Family Asteraceae)
Whitebrush
(Aloysia-gratissima)
Plant Family: Verbenaceae
June, November
A female ringed Exomalopsis (Exomalopsis analis): to the naked eye, this bee appears much darker overall than the other Exomalopsis species shown on this page.
Alternate view of female bee
A female ringed Exomalopsis seen from above. Note the dark and light hairs on the bee's lower hind legs.
The first segments of the bee's abdomen are black, wide and relatively hairless, contributing to the bee's overall dark appearance.
A female Exomalopsis analis on crucita
A female Exomalopsis analis from above
Similar Exomalopsis
Exomalopsis similis
Family: Apidae
Size: 6-7 mm (female), 4-5 mm (male)
Food plants at NBC:
Resinbush
Viguiera stenoloba
Seaside goldenrod
Romerillo
(Bidens alba)
(Family Asteraceae)
Silver-leafed nightshade
Solanum elaeagnifolium
(Family Solanaceae)
When found:
June-July, Sept. - Nov.
This is a female Exomalopsis similis. The patch of bright orange hairs on the back of the bee's thorax is visible even to the naked eye, and aids in identifying this species in the wild.
A female Exomalopsis similis on the head of a dime: this is the smallest of the six Exomalopsis species shown here.
Face of a female Exomalopsis similis
A male Exomalopsis similis
This is a small male Exomalopsis, between 5-6 mm.
The male Exomalopsis similis has dark tegulae, a dark abdomen striped with pale hairs and a yellowish tuft of hair at behind the scutellum.
A female Exomalopsis similis
A female Exomalopsis similis on the head of a dime: this is a small bee.
A male Exomalopsis similis
Solanum Exomalopsis
Exomalopsis solani
Family: Apidae
Size: 10 mm (female)
Associated plant at NBC:
Shrubby blue salvia
(Salvia ballotiflora)
Family: Laminaceae
Silverleaf nightshade
Solanum elaeagnifolium
(Family Solanaceae)
When seen: October-November
Female Exomalopsis solani
A female Exomalopsis solani on shrubby blue salvia. This species is a generalist pollinator, but it is associated with plants of the Solanaceae family, which includes such nightshades, tomatoes and peppers.
The bee's scutum is smooth and shiny, except toward the front, which is somewhat pitted. The tibia of each middle leg is covered predominantly with dark hairs.
Hind and middle legs of female bee: note the pale coloring of the hind-leg hairs. Exomalopsis birkmanni, shown below, closely resembles E. solani, but has bright orange hairs on its hind legs rather than pale ones like the E. solani shown here.
Rear view of abdomen of female Exomalopsis solani
Female Exomalopsis solani
Birkmann's Exomalopsis
Exomalopssis birkmanni
Family: Apidae
Size: 11 mm (female)
Associated plant at NBC:
Cenizo
(Leucophyllum frutescens)
Family: Scrophulariaceae
When seen: October 2019
A female Exomalopsis birkmanni on cenizo: to the naked eye, this species closely resembles Exomalopsis solani (shown above). The only visible difference is that E. birkmanni has bright orange scopal hairs on the hind legs and a bright orange tuft of hairs behind the scutellum.
Note the brilliant orange scopal hairs on this female bee's hind legs.
Profile view of bee
Dorsal view of female bee: the bee has a bare, somewhat shiny scutum (and a rust-colored tuft of hair on the hind edge of the scutellum).
A male Exomalopsis birkmanni: this bee was one of many males mobbing female Exomalopsis birkmanni as they visited cenizo.
Alternate view of male bee, on cenizo
Rear view of male bee
A female Exomalopsis birkmanni
A female Exomalopsis birkmanni
A male Exomalopsis birkmanni
Exomalopsis Species of the Lower Rio Grande Valley
CITE THIS PAGE: Sharp, Paula and Ross Eatman. "Anthophorula and Exomalopsis." Wild Bees of the National Butterfly Center of Mission, Texas. 15 Jan. 2019, http://www.wildbeestexas.com. Accessed [day/month/year guide accessed].