SHARP-EATMAN
NATURE
PHOTOGRAPHY
ID GUIDE TO WILD BEES
OF THE NATIONAL BUTTERFLY CENTER
Mission, Texas
EUCERA LONGHORN BEES
Eucera / Tetraloniella
LONGHORN BEES
Genus Eucera or Xenoglossa
Formerly Genus Tetraloniella
Before 2018, the bees featured on this page were classified for decades as Tetraloniella, a genus coined by the American entomologist William Harris Ashmead in 1899.
In 2001, entomologist Walter Laberge undertook a comprehensive study of Tetraloniella. For this work, titled "Revision of the bees of the genus Tetraloniella in the New World,” LaBerge examined 6,504 specimens of Tetraloniella, boiling them down to 35 distinct species, which he described in painstaking detail. Among them were Tetraloniella eriocarpi, Tetraloniela wilmattae and Tetraloniella panenalbata. shown on this page.
LaBerge's description of the genus Tetraloniella is still helpful today -- it accurately characterizes all of the longhorn bees featured below.
Laberge characterized Tetraloniella as follows: They are small to moderate-sized bees that superficially resemble longhorn bees of the genus Melissodes. The abdomens of Tetraloniella are often banded by pale hairs. Females usually have dense, and sometimes feathery, pollen-collecting (scopal) hairs on their hind legs. Males have long antennae, and yellow or pale markings on the mandibles. The male's clypeus and labrum (the mouthparts situated above and between the mandibles) are pale or yellow. Some males have toothlike projections on either side of the sixth segment (T6) of the abdomens.
Renaming of the genus Tetraloniella
In 2018, entomologists Dorchin et al. described the classification system for Eucerini (the longhorn bee tribe) as sprawling and messy, and they recommended a rehaul. Dorchin et al. proposed, among other changes, that bees occupying the genus Tetraloniella be resituated in the genus Eucera. New World Tetraloniella like those shown on this guide page were reclassified as Eucera (Xenoglossodes). This is the nomenclature that has been adopted on this page.
Renaming of the genus Eucera
FIve years after Dorchin et al, scientific nomenclature for Eucera underwent a new shift. A 2023 publication by Freitas et al. proposed the reclassification of some species of Eucera (Xenoglossodes), placing them in the resurrected genus Xenoglossa. Such species include, among others, Xengolossa albata (a sister species to Xenoglossa paenalbata, shown here).
As of 2026, popular entomology databases struggling to keep up with nomenclature changes (or simply waiting them out) classify former Tetraloniella species inconsistently. Bugguide.net, for example, lists three former Tetraloniella under the nomentclature Xenoglossodes albatus, Xenoglossodes eriocarpi and Xenoglossodes wilmatte. ITIS (Integrated Taxonomic Integration System) still retains Tetraloniella albata, Tetraloniella eriocarpi, Tetraloniella fasciatella, Tetraloniella paenalbata and Tetraloniella wilmattae. iNaturalist lists Xenoglossa albata but retains Tetraloniella eriocarpi, Tetraloniella fasciatella, Tetraloniella paenalbata and Tetraloniella wilmattae. The Discover Life Bee Species Guide and World Checklist retains Tetraloniella albata and Tetraloniella paenalbata but no longer lists former Tetraloniella eriocarpi, T. wilmattae or T. fasciatella under any genus.
A male Eucera fasciatella
TRAITS OF TETALONIELLA
LaBerge described Tetraloniella as moderate-sized bees that often have abdomens girded by bands of pale hairs.
Female tetraloniella usually have dense, and sometimes feathery, pollen-collecting (scopal) hairs on their hind legs.
Male tetraloniella have long antennae. On males, the clypeus and labrum (the face-parts above and between the mandibles) are yellow or pale.
A female Eucera paenalbata
Recommended reading:
Dorchin A, López-Uribe MM, Praz CJ, Griswold TL, Danforth BN. 2018. Phylogeny, new generic-level classification, and historical biogeography of the Eucera complex (Hymenoptera: Apidae). Molecular Phylogenetics and Evolution 119:81–92.
Freitas FV, Branstetter MG, Franceschini-Santos VH, Dorchin A, Wright KW, López-Uribe MM, Griswold TL, Silveira FA, Almeida EAB. 2023. UCE phylogenomics, biogeography, and classification of long-horned bees (Hymenoptera: Apidae: Eucerinae), with insights on using specimens with extremely degraded DNA. Insect Systematics and Diversity 7(4), 3: 1-21.
*TAXONOMY OF EUCERA
Order: Hymenoptera
Family: Apidae
Subfamily: Eucerinae
Tribe: Eucerini
Genus: Eucera
Subgenus: Xenoglossodes
Species shown below:
Eucera (Xenoglossodes) eriocarpi Tetraloniella eriocarpi -
Eucera (Xenoglossodes) fasciatella Tetraloniella fasciatella
Eucera (Xenoglossodes) paenalbata Tetraloniella paenalbata -
Eucera (Xenoglossodes) wilmattae Tetraloniella wilmattae -
Eucera (Former Tetraloniella) Species of the Lower Rio Grande Valley
Wilmatte's Longhorn Bee
Eucera (Xenoglossodes) wilmattae
Family: Apidae
Size: 10 mm - 2/5"
Associated plants at NBC:
Skeleton-leaf goldeneye
(Viguiera stenoloba)
Blanketflower
(Gaillardia pulchella)
Hoary blackfoot
(Melampodium cinereum)
Texas palafox
(Palafoxia texana)
Mexican hat
(Ratibida columnifera)
Tiny Tim
(Thymophylla tenuiloba)
Cowpen daisy
(Verbesina encelioides)
Plant Family: Asteraceae)
When and where seen:
NBC (Hidalgo Co.)
November 2018; April-May 2019, November 2023
Dos Venadas Ranch
Rio Grande City (Starr Co.)
April 26, 2023
This is a male Wilmatte's longhorn bee. The bee has a furry appearance, opaque black eyes and long antennae. Its hair is generally paler than that of the female bee.
The male Wilmatte's longhorn bee has pale-yellow mandibles and a pale-yellow labrum. The bee's clypeus is bright yellow.
Pale hairs cover much of the bee's head and thorax.
A female Wilmatte's longhorn bee: this is a golden bee with relatively short antennae and black eyes.
The female bee's face and thorax are covered with pale golden-brown hairs.
Dorsal view of female bee
A male Wilmatte's longhorn bee (Eucera wilmatte)
A female Wilmatte's longhorn bee
This species was named after Wilmatte Porter Cockerell, who first recorded it in 1917, in an article titled "Collecting Bees in Southern Texas." Cockerell discovered a single female specimen in Port Isabel, Texas, about 80 miles from Mission, where the National Butterfly Center is located. Cockerell noted that the bee was feeding on a "yellow composite" (an aster-family flower).
More than 100 years later, Wilmatte's longhorn bees still visit yellow composites at the National Butterfly Center.
Wilmatte's longhorn bees are enchanting insects. Males have bright yellow faces and exceptionally long antennae, which they curl inward at the tips like the ends of a mustache. Female bees' heads and bodies are are clothed in golden hair; males are covered in ivory hairs.
Both males and females eyes that are the opaque black of apple seeds. This trait is visible to the naked eye, and helps the casual naturalist distinguish this species easily from Melissodes longhorn bees of the Lower Rio Grande Valley, which have brightly-colored (usually green or blue) eyes.
Wilmatte's longhorn bees fly from April through November in the Valley. They are found in Cameron, Hidalgo and Starr Counties. This species' documented population is centered in South Texas. It ranges into Mexico, as least as far south Nuevo Leon, and has been sighted as far west as New Mexico. In the Valley, this species visits aster-family flowers nearly exclusively.
Fasciatella longhorn bee
Eucera (Xenoglossodes) fasciatella
Family: Apidae
Size: 10.5 mm (male)
Associated plant:
Shrubby blue salvia
(Salivia ballotiflora)
Plant family:Laminacaea
When and where seen:
May 30, 2021
Falcon State Park
Roma (Starr County)
A male Eucera fasciatella
A male Eucera fasciatella: males of this species have exceptionally long antennae.
Frontal view of male bee
The male bee has a wide face with a large ivory area, shaped like a crown topped by two knobs. The pale area covers the clypeus and extends more than halfway to the antennae.
The clypeus’s lower edge is rimmed with brown. The mandibles each have an ivory spot near the base, and are reddish toward the tips.
A male Eucera fasciatella
The shape and color of the ivory facial markings of the male Eucera fasciatella distinguish it from all other male longhorn bees of the Lower Rio Grande Valley.
In 1970, upon discovering this species, LaBerge placed the fasciatella longhorn bee in a new genus, which he named Pectinapis. Some females of this genus had comb-like hairs above the clypeus; all had hairy facial depressions above the clypeus. LaBerge speculated that female Pectinapis used their novel facial apparatus to rake pollen from flowers. He noted that some anthophorine (digger) bees had similar facial hairs, which they used to gather pollen. (The most common Valley species with such clypeal hairs is Anthophora capistrata, which collects pollen principally from salvia.)
Michener later reclassified Pectinapis fasciatella in Bees of the World: he felt that the bee's unusual facial characteristics did not merit the conjuring of a new genus. He cast this species into the same genus as Wilmatte’s longhorn bees, rechristening it Tetraloniella (Pectinapis) fasciatella.
Goldenweed longhorn bee
Eucera (Xenoglossodes) eriocarpi
Family: Apidae
Size: 7-9 mm (male and female)
Associated plants:
Texas palafoxia
(Palafoxia texana)
Arkansas dozedaisy
(Aphanostephus skirrhobasis)
Plant family: Asteraceae
When and where seen:
April 26, 2023
Dos Venadas Ranch
Rio Grande City, TX (Starr Co.)
A male Eucera eriocarpi
A male Eucera eriocarpi
Frontal view
Close-up of face: the clypeus of the male Eucera eriocarpi is ivory or pale yellow with a gold band on the bottom rim.
This is a female Eucera eriocarpi found by biologist Sam WIlhelm in north Texas in May, 2016. (All photos in this strip are Copyright 2026 Sam Wilhelm.)
The female Eucera eriocarpi is a black-eyed longhorn bee clothed with pale and golden hairs. It closely resembles the female E. wilmatte shown in this guide's previous entry.
Both the top and sides of the female Eucera eriocarpi's thorax are covered with light golden hairs (without any brown hairs).
A female Eucera eriocarpi
Photo Copyright 2026 Sam Wilhelm
Eucera eriocarpi is a medium-small black-eyed longhorn bee covered with golden or pale hairs. This species closely resembles E. wilmattae shown above. Eucera eriocarpi is uncommon in the Valley. It is nonetheless fairly widespread: it ranges through the southwestern United States, southward into much of Mexico, and westward into into Texas and Kansas. The male bee shown here was found in Starr County. The photographs of the female bee, found in North Texas, were supplied by biologist Sam Wilhelm.
The male Eucera eriocarpi is covered with mostly ivory hairs; on some individuals of the species, the hairs may be pale-rust or golden. The male bee has very long antennae, which appear red to the naked eye; underneath they are yellow or orange. The male's clypeus and labrum are yellow. The male Eucera eriocarpi can be distinguished from the male E. wilmattae in the field by examining the antennae: on E. wilmattae, the top 3 1/2 segments of the antennae are dark; male Eucera eriocarpi lack this trait.
Female Eucera eriocarpi and E. wilmatte can be separated n part by three traits. (1) On the female Eucera erocarpi, the pale hair bands on the abdomen run together; on E. wilmatte, the tergal bands are more distinct and separated. (2) On the female E. eriocarpi, the yellow area on the clypeus is broader than it is in E. wilmattae. (3) The labrum of E. eriocarpi is all pale; on the female E. wilmattae, the labrum is partly or entirely black.
Woolly-white longhorn bee
Eucera (Xenoglossodes) paenalbata
Family: Apidae
Size: 10.5 mm (female)
Associated flora:
Mexican hat
Rabatida columniferra
Cowpen daisy
Verbesina enceloides
Family: Asteraceae
When seen:
June 21 2021
Campos Viejos Ranch,
Rio Grande City (Starr Co.)
A female woolly-white longhorn bee (Eucera paenalbata)
Eucera paenalbata is a small bee with a robust build; white and pale-orange thorax hairs; golden-pink tegulae; and pale-blue eyes.
Dorsal view of female bee and the pale-rust hairs on its thorax
Close-up of the female's vertex & thorax
Frontal view of female bee
A female woolly-white longhorn bee
Eucera paenalbata is a small and pretty longhorn bee, with pale-blue eyes; white and light-orange thorax hairs; golden-pink tegulae; and an abdomen clothed in pale hairs. This species’ scientific name (paen- or “almost”) is a nod to Eucera albata, a similar white-and pinkish-gold bee first described by Cresson in 1872.
LaBerge first described the woolly-white longhorn bee in 2001, christening it Tetraloniella paenalbata. Like Eucera wilmattae shown above, Eucera paenalbata exhibits the characteristics of the former genus Tetraloniella: the female bee’s hind-leg scopal hairs are dense and plumose. The male Eucera paenalbata has a pale clypeus and labrum, and its mandibles are pale at the base.
This species ranges from Colorado and Kansas through Texas and Tamaulipas, and as far south as Mazatlán. LaBerge recorded Eucera paenalbata feeding on purple dalea (Dalea lasiathera), a pea-family plant. The female bee found here was foraging on the composite flowers Mexican hat and cowpen daisy.
CITE THIS PAGE: Sharp, Paula and Ross Eatman. "Eucera." Wild Bees of the National Butterfly Center of Mission, Texas. 15 Jan. 2019, http://www.wildbeestexas.com. Accessed [day/month/year guide accessed].