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.

Exomalopsis mellipes - (c) Copyright 2018 Paula Sharp

A female Exomalopsis, showing the bushy scopal hairs typical of the genus

Anthophorula compactula bee - (c) Copyright 2019 Paula Sharp

A male Anthophorula

Traits distinguishing Exomalopsis vs. Anthophorula bees

Exomalopsis hind leg & scopal hairs - (c) Copyright 2018 Paula Shap

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

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

Red Prickly Poppy

Argemone sanguinea

Plant family: Papaveraceae

When seen:  April 2019  

Anthophorula compactula bee - (c) Copyright 2019 Paula Sharp

A female Anthophorula compactula

Detailed Photographs
of female bee: 

Detailed Photographs
of male bee: 

Anthophorula compactula bee - (c) Copyright 2019 Paula Sharp

A male Anthophorula compactula

Anthophorula compactula bee - (c) Copyright 2019 Paula Sharp

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 marginal 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

(Viguiera stenoloba)

Seaside goldenrod

(Solidago sempervirens)

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)

Exomalopsis snowi - (c) Copyright 2018 Paula Sharp

A female Exomalopsis snowi

Exomalopsis snowi - (c) Copyright 2018 Paula Sharp

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

(Solidago sempervirens)

Spanish needles

(Bidens alba)

Plant family:  Asteraceae

Prickly Malvastrum

(Malvastrum coromandelianum)

Plant Family:  Malvaceae

Texas Sage 

(Leucophyllum frutescens)

Whitebrush

(Aloysia-gratissima)

Plant Family:  Verbenaceae

When found: 
September and November 2018,
& July and October 2019

Exomalopsi mellipes - bee - (c) Copyright 2018 Paula Sharp

A female Exomalopsis mellipes

Exomalopsis mellipes - (c) Copyright 2019 Paula Sharp

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 

Exomalopsis analis (female) - (c) Copyright 2018 Paula Sharp

A female Exomalopsis analis on crucita

Exomalopsis analis (female) - (c) Copyright 2018 Paula Sharp

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

(Solidago sempervirens)

Spanish needles

(Bidens alba)
(Family Asteraceae)

Silver-leafed nightshade
Solanum elaeagnifolium
(Family Solanaceae)

When found:

September & November 2018

July & October 2019

Exomalopsis similis (female) - (c) Copyright 2018 Paula Sharp

A female Exomalopsis similis

Exomalopsis similis (female) - (c) Copyright 2018 Paula Sharp

A female Exomalopsis similis on the head of a dime:  this is a small bee.

Exomalopsis similis bee - (c) Copyright 2019 Paula Sharp

A male Exomalopsis similis 

Exomalopssis birkmanni

Family:  Apidae

Size:  11 mm  (female)

Associated plant at NBC:  

Texas sage

(Leucophyllum frutescens)

Family:  Scrophulariaceae

When seen:  October 2019  

Exomalopsis brmanni bee - (c) Copyright 2019 Paula Sharp

A female Exomalopsis birkmanni

Exomalopsis birkmanni - (c) Copyright 2019 Paula Sharp

A female Exomalopsis birkmanni

Permissions and Copyright Information:   All images on this site are (c) Copyright 2018-2019 Paula Sharp and Ross Eatman.  All rights reserved. All photographs are protected by registered copyright.  Please contact Sharp-Eatman Nature Photography for written permission before using any of these images for any purpose. 

Last updated November 2019

 1-15-19