SHARP-EATMAN
NATURE
PHOTOGRAPHY
Panamanian Masked Bee
Hylaeus (Hylaeana) panamensis
Family: Colletidae
Size: 4.5 mm (female)
Associated plants at NBC:
Texas palafox
(Palafoxia texana)
Plant Family: Asteraceae
When Seen:
November 2019
ID GUIDE TO WILD BEES
OF THE NATIONAL BUTTERFLY CENTER
Mission, Texas
MASKED BEES
Hylaeus
Masked Bees
Genus Hylaeus
Masked bees, sometimes called "yellow-faced bees," comprise the genus Hylaeus, and belong to the same bee family -- Colletidae -- as the cellophane bees shown on the previous page of this guide. Masked bees are found throughout the world, on every continent except Antarctica.
Masked bees are easy to overlook -- they are small and slender and easily mistaken for black ants. Typically, masked bees have dark bodies; yellow designs or "masks" on their faces; parti-colored yellow-and-black legs; and yellow markings on their thoraxes. The bees' abdomens are usually entirely black, a trait that helps distinguish them from dark-bodied wasps, which often have abdomens striped with yellow or other colors.
Many Hylaeus build tunnel-like nests in dead plant stems. (Some construct nests in pre-existing cavities like nail holes; in burrows made by beetles or other bees; or even in the cells of wasp nests.) Because of their preference for woody nesting materials, bees of the genus Hylaeus (Latin for "of the woods") often abound near woodland habitats.
Unusual pollination practices of masked bees
Most female bees carry pollen on scopal hairs located on their legs or under their abdomens. Female masked bees, however, carry pollen internally, in stomach-like organs. Upon arrival at their nests, female bees regurgitate the pollen and store it for future offspring. When nesting, female Hylaeus secrete a substance said to have a texture similar to polyester, which the bees use to coat the brood cells in which they deposit their eggs.
Masked bees have short tongues. The bees' small size allows them to enter into deep-throated flowers to harvest pollen and nectar, unlike large short-tongued bees. In the Valley, Hayleaus show a strong preference for small-flowered plants such as goldenrod, palafox and fleabane.
Identification information:
There are more than a dozen species of masked bees in Texas. Most are small to very small, between 4 to 6 mm. In most species, females are larger than their male counterparts.
Differentiation among species is difficult to undertake with the naked eye, because the bees are so small and nuances in their appearance minute. Species identification usually requires the aid of a macro lens or other magnifier.
One trait that helps to distinguish masked bee species from one another is the nature and size of the yellow or white "masks" or markings on the bees' faces. These vary from one species to another. Some examples are shown in the accompanying photo strip.
Facial markings also differ on male and female masked bees of the same species: markings of males tend to cover a large area of the face, while on females, the markings are smaller and often restricted to two bands or to two roughly triangular shapes on either side of the bee's face.
Other markings on the bees' bodies are also used to differentiate species. For example, masked bees often have yellow or pale marks on the tegulae (where the wing joins the body); near the tegulae; and on their legs. Many masked bees have a collar of yellow lining the front of the thorax (the pronotum). The size and placement of such markings differ from species to species.
Three species from the Lower Rio Grande Valley, representing two subgenera, Prosopis and Hylaeana, are shown below. The subgenus Prosopis is holarctic (found throughout northern continents of the world). Both the modest masked bee and affiliated masked bee shown below belong to this subgenus. As noted below, differentiating between these two species is tricky.
Hylaeana is a largely subtropical subgenus, represented by a single species within Texas -- the Panamanian masked bee, shown below. The Panamanian masked bee is striking when viewed with magnification, because it has a partly-orange clypeus (the face part above the jaws). Hylaeus species within the United States that have such exotic coloring are unusual and tend to inhabit the southernmost part of the country.
A female Panamanian masked bee (Hylaeus panamensis)
COMPARISON OF FACIAL MARKINGS
OF SIX MASKED BEES NATIVE TO TEXAS
This photo strip shows the faces of masked bees found in Texas. This first image is of a female affiliated masked bee (Hylaeus affinis)
A female Panamanian masked bee (Hylaeus panamensis)
A male modest masked bee (Hylaeus modestus)
A female modest masked bee (Hylaeus modestus)
A female Cresson's masked bee (Hylaeus cressoni)
A male slender-faced masked bee (Hylaeus leptocephalus).
(Top row, left to right): a female affiliated masked bee; a female Panamanian masked bee; a male modest masked bee; and (bottom left) a female modest masked bee; a female Cresson's masked bee; and a male slender-faced bee. Male bees tend to have masks that cover their entire faces, while females have a pair of roughly-triangular markings that rim their compound eyes. Masks tend to be pale yellow or white. On some species such as the Panamanian masked bee, the clypeus (the face part above the bee's jaws) may be orange or yellow. Differences in facial markings are used to identify Hylaeus species, although in some cases -- such as the female affiliated vs. female modest masked bee -- such differences may be subtle.
TAXONOMY OF HYLAEUS BEES
Order: Hymenoptera
Family: Colletidae (plasterer and masked bees)
Genus: Hylaeus (masked bees)
Subgenus: Hylaeana
Species found at the NBC:
Hylaeus panamensis (Panamanian masked bee)
Subgenus: Prosopis
Species found at the NBC:
Hylaeus affinis (Affiliated masked bee)
Hylaeus modestus (Modest masked bee)
Panamanian Masked Bee
Hylaeus (Hylaeana) panamensis
Family: Colletidae
Size: 4.5 mm (female)
Associated plants at NBC:
Texas palafox
(Palafoxia texana)
Plant Family: Asteraceae
When Seen:
November 2019
A female Hyaleus panamensis
The"mask" of the female Panamanian masked bee is comprised of two roughly triangular pale-yellow shapes bracketing a yellow-and orange patch that covers part of the clypeus (the face part above the bee's jaws).
Dorsal view of the female bee's head and thorax: note the broken yellow pronotal collar at the front of the bee's thorax.
The female bee also has pale-yellow markings on its legs; on the pronotal lobe; and its tegula.
A female Panamanian masked bee (Hylaeus panamensis)
Face of a female Panamanian masked bee
The Panamanian masked bee is considered a neotropical species, and is found from Panama through the southwestern United States. John L. Neff, President of the Central Texas Melittological Institute, has noted that within Texas, this species occurs near the border, principally in Hidalgo and Cameron Counties; he has seen one specimen from Edwards County.
Masked bees of the subgenus Hylaeana run small even for Hylaeus (3.5 – 4.5 mm). They have pitted thoraxes and abdomens whose first two segments (T1-T2) are smooth and relatively unpitted.
The orange clypeus of the female bee shown here is a notable trait. Only a handful of North American masked bees have partly or mostly orange-yellow clypeuses. (Among these are Hylaeus flammipes, H. formosus, H. rudbeckia and H. volusiensis) .
Associated plants at NBC:
Texas palafox
(Palafoxia texana)
Plant Family: Asteraceae
When Seen:
November 2019
Affiliated Masked Bee
Hylaeus (Prosopis) affinis
Family: Colletidae
Size: 6.5 mm (female)
A female affiliated masked bee (Hylaeus affinis)
A female Hylaeus affinis
Dorsal view of female Hylaeus affinis: note the yellowing markings on the pronotal collar (at the front of the thorax)
Face of female Hylaeus affinis
Close-up of vertex
Face of a female Hylaeus affinis masked bee
Female masked bees of the species Hylaeus affinis and Hylaeus modestus (shown below) are very similar. The challenge of distinguishing them illustrates how difficult it can be to parse out different Hylaeus bees into separate species. Female affiliated and modest masked bees are similar in size and have nearly identical facial masks; usually have yellow markings on the pronotal collar; and have pale markings on their legs. Both species visit a wide range of plants and are found throughout the United States.
One minute trait that sometimes helps distinguish female Hylaeus affinis from Hylaeus modestus females is that on H. affinis, there are pale markings on the female bee's tegulae (the plates where the wings join the body), and on the smaller, tegula-like structures partly hidden under the tegulae. These are shown in the photo strip above left. Female Hylaeus modestus bees lack yellow markings on these body parts.
Modest Masked Bee
Hylaeus (Propsopis) modestus
Family: Colletidae
Size: 5-7 mm (male)
4.5-7 mm (male)
Food plants at NBC:
(Croton humilis)
Plant Family: Euphorbiaceae
When seen:
November 2018
A male modest masked bee (Hylaeus modestus)
A male modest masked bee found at the National Butterfly Center.
Dorsal view of the male modest masked bee
Note the yellow pronotal collar on the front of the male bee's thorax.
Note also the yellow markings on tthe legs of the male Hylaeus modestus. The markings on both the pronotal collar and the legs of the male Hylaeus affinis are similar.
This female modest masked bee (Hylaeus modestus) was not found at the NBC. It is shown here simply to illustrate differences in males and females of this species.
Both male and female modest masked bees usually have a collar of yellow at the front of the thorax. This is a female bee.
Female modest masked bees have two roughly triangular patches of yellow on their faces, rather than masks that cover the entire face like their male counterparts.
A male modest masked bee
A female modest masked bee
As noted in the entry above, female modest masked bees (Hylaeus modestus) and female affiliated masked bees (Hylaeus affinis) are very similar.
Male modest masked bees can be told from male Hylaeus affinis by examining the bees' antennal scapes (the lowest antennal segments). The scapes of Hylaeus modestus males are black, while those of H. affinis males have yellow markings on them.
The Hylaeus modestus male typically has a yellow facial mask whose outer edges follow the inner edge of the bee’s compound eyes, from bottom to top. Although the male bee’s antennal scapes are black, the rest of each antennae is dark above and golden brown below. Most, but not all male Hylaeus modestus have yellow markings on the pronotal collar. On some male modest masked bees (but not the females), there is a yellow mark on each tegula (the node where the bee’s wing meets its body) and on the smaller tegula-like plate partly hidden underneath it.
Masked Bee Species of the National Butterfly Center
CITE THIS PAGE: Sharp, Paula and Ross Eatman. "Hylaeus." Wild Bees of the National Butterfly Center of Mission, Texas. 15 Jan. 2019, http://www.wildbeestexas.com. Accessed [day/month/year guide accessed].