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

Hylaeus panamensis masked bee - Copyright 2019 Paula Sharp

A female Panamanian masked bee

Hylaeus panamensis masked bee - Copyright 2019 Paula Sharp

Face of a female Panamanian masked bee

Masked bees of the subgenus Hylaeana are small (3.5 – 4.5 mm) ; and have pitted thoraxes; and  have abdomens whose first two segments 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) Hylaeus formosus belongs to the same subgenus (Hylaeana) as the Panamanian masked bee, but within the United States is found only in Florida, and its first abdominal segment is reddish orange.  The Panamanian masked bee, by contrast, has an entirely black abdomen.


The Panamanian masked bee is considered a neotropical species, and is found from Panama through the southwestern United States.  Jack 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.

Associated plants at NBC: 

Texan palafox

(Palafoxia texana)   
Plant Family: Asteraceae


When Seen:

November 2019

Affiliated Masked Bee

Hylaeus (Prosopis) affinis

Family:  Colletidae

Size:      6.5 mm (female)

Hylaeus affinis masked bee - Copyright 2019 Paula Sharp

A female Hylaeus affinis masked bee

Hylaeus affinis masked bee - (c) Copyrigth 2019 Paula Sharp

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 pronotal collars (at the front of the thorax); 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 nodes 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  

Masked bee - Hylaeus modestus - (c) Copyright 2019 Paula Sharp

A male modest masked bee

Hylaeus modestus - modest masked bee - (c) Copyright 2019 Paula Sharp

A male modest masked bee

Hylaeus modestus modest mske bee - (C) Copyrght 2019 Paula Shap

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' antenna scapes (the bottom antennal segments).   The scapes of Hylaeus modestus males are black, while those of  H. affinis males have yellow markings on them.

The H. 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 H. modestus bees have a yellow pronotal collar (at the front of the thorax.) 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. 


Mission, Texas


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 bees build tunnel-like nests in dead plant stems; others 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.

Unusual pollination practices of masked bees


Unlike most bees, female masked bees do not carry pollen on scopal hairs located on their hind legs or undersides.  Instead, female masked bees carry pollen internally, in stomach-like organs.  Upon arrival at their nests, female bees regurgitate the pollen and store it for future offspring.


Female masked bees build nests in the stems of pithy-stemmed plants. The bees secrete a substance said to have a texture similar to polyester, with which they coat the brood cells in which they deposit their eggs. Because of their preference for woody nesting materials, bees of the genus Hylaeus (Latin for  "of the woods")  often abound near woodland habitats.


Masked bees have short tongues, but according to the Xerces Society's Guide to Attracting Native Pollinators, the bees' small size allows them to enter into deep-throated flowers to harvest pollen and nectar, unlike large short-tongued bees.  Masked bees at the National Butterfly Center show a strong preference for small-flowered plants such as goldenrod, palafox and fleabane. 

Identification information:


There are more than a dozen species of maskeld 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 at right.


Facial markings also differ in male and female masked bees:  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 representing two subgenera, Prosopis  and Hylaeana, have been documented at the National Butterfly Center.  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 the United States -- 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 county.

A female Panamanian masked bee (Hylaeus panamensis)

Comparison of facial markings of six Texas masked bees:  (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 seem negligible.


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: 
affinis (Affiliated masked bee) 

      Hylaeus modestus (Modest masked bee)

Masked Bee Species of the National Butterfly Center

Last updated January 2020