ID GUIDE TO WILD BEES
OF THE NATIONAL BUTTERFLY CENTER
Mission, Texas
SHARP-EATMAN
NATURE
PHOTOGRAPHY
ID GUIDE TO WILD BEES
OF THE NATIONAL BUTTERFLY CENTER
Mission, Texas
EXOMALOPSIS & ANTHOPHORULA BEES
Exomalopsis Species of the National Butterfly Center
THE BEE TRIBE EXOMOLOPSINI
Genus Exomolopsis
Genus Anthophorula
The bee tribe Exomalopsini contains two genera of similar bees: Exomalopsis and Anthophorula.
GENUS EXOMALOPSIS: THE NOT-SO-UGLY BEE
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 bees are frequent visitors to the National Butterfly Center during the 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".
GENUS ANTHOPHORULA: THE SMALLER COUSIN
Anthophorula bees, close cousins in the Exomalopsini tribe, greatly resemble Exomalopsis bees. Anthophorula is a genus of furry bees that often have dark abdomens banded with pale hairs. Female Anthophorula have luxuriant scopal hairs on their back legs. Males sport long antennae and often have yellow facial markings.
As a rule, Anthophorula bees tend to run smaller than Exomalopsis bees. (In Greek, the name Anthophorula means "little flower bearer".) Anthophorula bees tend to appear at the National Butterfly Center in early spring, shortly before prickly pear cactus begins blooming in Hidalgo County.
Anthophora vs. Exomalopsis
Exomalopsis and Anthophorula bees 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 photo strip at right, separate these two genera. According to entomologist Charles D. 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 wing 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 bees 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 bees 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 bees are pollinator generalists. At the NBC, Exomalopsis bees are frequent visitors to an array of wild and garden flowers, most notably skeleton-leaf goldeneye, crucita, croton and mallows.
Anthophorula bees 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 surrounding areas. Nonetheless, this species is known to visit a wide gamut of plants.
Some Exomalopsis and Anthophorula bees are capable of 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 used to pollinate such crops. At the National Butterfly Center, Exomalopsis bees can be observed visiting the wildflower silver-leaf nightshade, a member of the Solonaceae family.
Species range and Identification information:
Both Exomalopsis and Anthophorula bees 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.
There are approximately 40 species of Anthophorula in the United States. Most of these are found in California or the southwest, although one species of Anthophorula, A. pygmaeia, occurs throughout most of the U. S. At least 14 Anthophorula species have been documented in Texas or along the Texas-Mexico border: Anthophorula asteris, A. compactula, A. completa, A. consobrina, A. ignota, A. interrupta, A. lacticincta, A. micheneri, A. morgani, A. nitens, A. parva, A. pygmaea, A. sidae and A. texana.
Little photographic documentation of Exomalopsis and Anthophorula species is available on the Internet, 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 Jack 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 female Exomalopsis, showing the bushy scopal hairs typical of the genus
A male Anthophorula
This is an Exomalopsis bee. 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 bee: it is a mere 5.5 mm (1/5 in.) long. Anthophorula bees tend to be smaller than Exomalopsis bees.
View of vertex and thorax of an Exomalopsis. The thoraxes of both Exomalopsis and Anthophorula bees are often shiny and relatively hairless.
This is an Anthophorula. Both Anthophorula and Exomalopsis bees have short parallel hairs that line the inner edges of their compound eyes.
Face of female Exomalopsis. In Exomalopsis bees, both the male and female have a dark clypeus (the part above the jaws).
By contrast, male Anthophorula bees, like that shown here, may have yellow clypeuses.
Traits distinguishing Exomalopsis vs. Anthophorula bees
Leg of a female Exomalopsis
TAXONOMY OF EXOMALOPSIS BEES
Order: Hymenoptera
Family: Apidae
Subfamily: Apinae
Tribe: Exomalopsini
Genus: Exomalopsis
Species shown below:
Anthophorula (Anthophorula) compactula
(Compact 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 & Exomalopsis Species of the National Butterfly Center
Detailed Photographs
of female bee:
Compact Anthophorula
Anthophorula compactula
Size: 4.5 mm (male); 7 mm (female)
Associated plants
Prickly Pear Cactus
(Opuntia engelmannii)
Twisted-rib cactus
(Thelocactus setispinus)
Plant family: Cactaceae
Argemone sanguinea
Plant family: Papaveraceae
When seen: April 2019
A female Anthophorula compactula
This is a female compact Anthophorula.
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.
This is a male compact Anthophorula.
The male Anthophorula compactula has a yellow clypeus (the face part above the jaws). This is a trait common to many male Anthophorula species.
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.
A male Anthophorula compactula
A male Anthophorula compactula on the head of a dime
In the Lower Rio Grande Valley of Texas, this beautiful small bee emerges in spring. Male compact Anthophorulas appeared at the National Butterfly Center and nearby nature parks in early April 2019, feeding on Texas prickly pear cactus. Female bees surfaced ten days later, and were 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 Athophourla compactula has only two submarginal cells. Other notable traits that help in identifying this Anthophorula include: (1) male bees have yellow masks on their lower faces; (2) male bees' antennae are striped black-and-yellow on their hind surfaces; (3) female bees have black hairs on the lower portion of each hind leg.
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:
November 2018, June 2019
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 nodes where the bee's wings join its body) and most of the scopal hairs are orange.
A male Snow's Exomalopsis (Exomalopsis snowi)
As is true of male bees generally, male Exomalopsis bees do not gather pollen and thus lack scopal hairs on their legs.
A female Exomalopsis snowi
A male Exomalopsis snowi
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
Spanish needles
Plant family: Asteraceae
Prickly Malvastrum
(Malvastrum coromandelianum)
Plant Family: Malvaceae
Texas Sage
(Leucophyllum frutescens)
Plant family: Scrophulariaceae
Whitebrush
(Aloysia-gratissima)
Plant Family: Verbenaceae
When found:
September and November 2018,
& July and October 2019
A female Exomalopsis mellipes
This species is distinguished from other Exomalopsis bees in part by the colors of its leg hairs and tegulae (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.
This is the rear view of the female bee.
The male Exomalopsis snow is a robust bee with reddish legs, a reddish abdomen and red tegulae (the nodes 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 the antennae.
The male bee's eyes are green.
Rear view of 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
When found:
November 2018
June 2019
A female Exomalopsis analis on crucita
A female ringed Exomalopsis (Exomalopsis analis). To the naked eye, this bee appears much darker overall than the other Exomalopsis bees shown on this page.
A female ringed Exomalopsis seen from above. Note the large dark swaths of hair on the bee's 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 from above
Similar Exomalopsis
Exomalopsis similis
Family: Apidae
Size: 6-7 mm (female)
Size: 4-5 mm (male)
Food plants at NBC:
Skeleton-leaf goldeneye
Viguiera stenoloba
Seaside goldenrod
Spanish needles
(Bidens alba)
(Family Asteraceae)
Silver-leafed nightshade
Solanum elaeagnifolium
(Family Solanaceae)
When found:
September & November 2018
July & October 2019
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 four Exomalopsis bees shown here.
Face of a female Exomalopsis similis
This is a small male Exomalopsis, between 5-6 mm.
Male Exomalopsis: the bee has dark tegulae, a dark abdomen striped with pale hairs and a yellowish tuft of hair at the back of the abdomen.
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 2019
Female Exomalopsis solani
A female Exomalopsis solani on shrubby blue salvia. This species is a generalist pollinator, but is associated with members of the genus Solanum, which includes such plants as nightshade, tomato 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. A different bee known as Exomalopsis birkmanni 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 solani
Female Exomalopsis solani
Exomalopssis birkmanni
Family: Apidae
Size: 11 mm (female)
Associated plant at NBC:
Texas sage
(Leucophyllum frutescens)
Family: Scrophulariaceae
When seen: October 2019
A female Exomalopsis birkmanni on Texas sage: to the naked eye, these bees closely resemble Exomalopsis solanum (shown above). The only visible difference is that E. bikmanni bees have bright orange scopal hairs on their legs and a bright orange tuft of hairs behind the thorax.
Note the brilliant orange scopal hairs onthis female bee's hind legs.
Profile view of bee
Dorsal view of female bee: The bee has a bare, somewhat shiny scutum with a rust-colored tuft of hair on its hind edge.
A male Exomalopsis birkmanni. This bee was one of many males mobbing female Exomalopsis birkmanni that were visiting Texas sage.
Alternate view of male bee, on Texas sage
Rear view of male bee
A female Exomalopsis birkmanni
A female Exomalopsis birkmanni
A male Exomalopsis birkmanni