ID GUIDE TO WILD BEES - NEW YORK

CELLOPHANE BEES

CELLOPHANE BEES:    Bees of the genus Colletes line the cells of their nests with a waterproof material which, when dry, resembles clear plastic.  Accordingly,  they are sometimes called “cellophane bees”  or, alternately, “polyester bees”.   Cellophane bees are equipped with unusual forked tongues, which they use to paint the plastic-like material onto their nest walls in order to keep their nests dry.  The bees produce the material from a special abdominal organ called the Dufour’s gland, named after French naturalist Léon Jean Marie Dufour, who first recorded his fascination with the bees’ fabrication of plastique in 1835

 

According to  the Xerces Society's Guide to Attracting Native Pollinators, cellophane bees also spray their egg-cell walls with a natural fungicide and bacteriacide, linalool, secreted from a gland in the bees' mandibles.  After coating their cells, the bees fasten their eggs onto the cell walls rather than leaving them on nest floors where moisture might collect.  The bees provision their cells by mixing pollen and nectar together to make a liquid “bee bread” for their offspring; these provisions are stored in cellophane sacs that look a little like elongated plastic sandwich bags.  The special measures taken by the bees to protect their eggs against water and fungus allow them to build nests near stream banks and other areas with wet soils.

 

Cellophane bees are solitary.  They construct individual nests in the ground, excavating tunnels that exit through small round holes.  Despite their solitary status, the bees tend to build their nests near one another.  Groups of nesting cellophane bees sometimes number into the tens of thousands.  These bees, however, are non-aggressive and do not form swarms.  They are important pollinators of spring trees, crops and wildflowers. 

A Broad-footed cellophane bee flying amid tomatillo blossoms. 

Broad-footed Cellophane Bee
Colletes latitarsis

3/10" - 2/5" (medium-sized)

The tomatillo is a plant originating in Mexico and bearing green tomato-like fruits encased in papery husks.  Cultivated by the ancient Aztecs as long ago as the 14th Century, the tomatillo has made its way into the United States and into our gardens and cuisine.  At the heart of this plant's long history is the beautiful broad-footed cellophane bee, a pollinator that specializes in the flowers of tomatillos (Physalis philadelphica) and other native plants of the genus Physaylis.


Broad-footed cellophane bees appear at Stone Barns Center for Food and Agriculture in mid-August, when tomatillo plants in the mixed flower-and-vegetable gardens are in bloom.   They remain in the garden for just a few weeks, through the end of summer.

 

These bees are occasionally seen as well on Chinese lantern (Physalis alkekengi), a plant that grows in Stone Barns’ cut-flower fields during the same period.  Chinese lantern, although Asian in origin, is a relative of the Mexican tomatillo.  The two plants greatly resemble one another. Chinese lanterns have bright orange papery calyxes similar to the tomatillo's green calyx, as shown in the photo strip at right.  Broad-footed cellophane bees also can be found pollinating the closely-related native plant known as ground cherry (Physalis heterophylla), which grows in late summer along park trails. 

 

Bees that specialize in plants of a particular family or genus are called oligogetic.  Despite the fact that broad-footed cellophane bees are clearly oligolectic, they have been documented foraging at times on other flowers -- among them, goldenrod, snowberry blossoms, tall bellflower, alfalfa, sweet clover, swamp smartweed, spotted water hemlock, bugleweed and yellow passionflower. 

The nests of broad-footed cellophane bees may be preyed upon by the cleptoparasitic two-banded Epeolus, shown on the cuckoo bee page of this guide.

 

Identification:  Broad-footed cellophane bees have dark abdomens striped with clearly delineated white bands; thoraxes rimmed with a mixture of light and dark hair; broad heads; and heart-shaped faces that are covered with pale hair below the level of the antennae.  Their antennae are medium-length and dark and their wings are transparent brown.  Broad-footed cellophane bees are about 1/3" in length or slightly smaller or larger. 

 

The broad-footed cellophane bee can be distinguished from other members of its genus by the extremely broad basitarsi (bottom segments) of its back legs -- as shown in the photo strip at right, the bee's basitarsus is about half as wide as it is long.  Broad-footed cellophane bees also can be identified by their association with tomatillos and related plants.  The unequal cellophane bees shown lower down on this page are somewhat similar in appearance, but they emerge in our area in early spring, long before tomatillos begin bearing fruit.  Their basitarsi are much narrower than those of broad-footed cellophane bees.

 

These bees somewhat resemble Wilkes Andrena bees (shown elsewhere in this guide), but are more robust, have more clearly defined black-and-white striping, and lack the long antennae of those Andrenas.  Finally, while both types of bees nest in the ground and tend to group in aggregations, the aggregations of cellophane bees tend to be denser and more extensive than those of Andrena bees.

 

 

TAXONOMY  -  Broad-footed Cellophane Bee

Order:  Hymenoptera 

Family:  Colletidae (Plasterer and Masked Bees)

Genus:  Colletes (Cellophane bees)

Species:  Colletes latitarsis  (Broad-footed Cellophane Bee)

All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography

Unequal cellophane bee  nests

Unequal cellophane bees are among of the very first pollinators to emerge in spring in the Northeast -- in Westchester County, New York, these bees surface right after the last March snows begin to melt, when the weather is still chilly.  The bees remain visible for only a brief period, usually through the end of April.

 

A telltale sign of unequal cellophane bees' presence is the appearance of groups of thumbtack-sized holes in bare areas of leaf-littered or grassy slopes.  The holes, shown at right, are the entrances to the bees' nests.  The holes typically are surrounded by small mounds of dirt -- this is soil excavated by female bees as they busy themselves digging tunnels in which to build their brood cells. 

 

These  bees are amusing to watch.  The females often hunker down at the mouths of their tunnels, guarding their nests and staring out at the world.  If you observe them carefully, you may see the female bees surface in order to push dirt from their holes with the tips of their abdomens (as shown in the photo strip at bottom right).  The bees' tunnels extend as deep as eighteen inches under the soil.

 

Unequal cellophane bees build nest aggregations under the protective branches of beech trees in the Rockwood Hall section of the Rockefeller State Park Preserve.  Males emerge first, digging their own tunnels to the surface.  They spend their days feeding on nearby blossoming maples and patrolling nesting areas, surveying their territories and searching for mates.  During the night, males sleep in their own individual nest holes.  As female bees emerge, their nests become interspersed with those of the males; male and female nest holes may lie just a few inches from one another.  These bees fly parallel to the ground, just a few inches above it, as they patrol or search for their nest entrances.

 

Unequal cellophane bees are important generalist pollinators of a variety of wild trees and shrubs that blossom in spring -- among them, maple, redbud, willow, viburnum and chokecherry.  These bees also pollinate gooseberries and blueberries.  Both male and female bees can be observed pollinating maple and willow trees in the park.  Unequal cellophane bees also frequent blossoming pussy willows half-submerged in water along the banks of Swan Lake.  The bees sometimes pile close to one another, resting in groups on pussy willow twigs.

 

Identification:   Unequal cellophane bees have dark heads, dark eyes, dark thoraxes (midsections) and predominantly dark legs.  Their heads, thoraxes and legs are covered with mixed pale and dark hairs.  Their abdomens are dark with ivory stripes rimmed with pale hairs.  Like all Colletes bees, unequal cellophane bees have faces that are  “heart-shaped”:  a cellophane bee's eyes slant toward one another and its head tapers downward toward its jaw. 

 

Male unequal cellophane bees are smaller (around 1/3") than females (2/5" -  4/7") and have notably furry- looking faces covered with patches of pale hair. The legs of the male bees may be reddish.  The tarsi (bottom leg segments) of females bees are dark, although their leg spurs may be reddish.  Female cellophane bees carry pollen on the upper parts of their hind legs, like Andrena mining bees.

 

Note on "sand bees" or "sand wasps":  Unequal cellophane bees are sometimes confused with a variety of wasp known locally as a "sand bee," which builds nests in sandy areas of New York lawns. The nests of sand bees (also called sand wasps) resemble those of unequal cellophane bees -- they are single holes surrounded by small mounds -- but the wasps are very different in behavior from cellophane bees. Sand wasps can be aggressive and have a painful sting.  while cellophane bees are nonaggressive.

 

To the extent possible, the nests of cellophane bees should be left undisturbed by lawn mowers and pesticides. Cellophane bees are important pollinators of your yard's trees and shrubs. Their nests are good for soil aeration, and the bees cause little inconvenience, in part because they tend to be short-lived. In our area, unequal cellophane bees disappear before May.  Insecticides tend to be ineffective against them, because the bees' solitary tunnels are unconnected; thus, exterminators' promises to eradicate the bees' "nests" though insecticide applications are misleading.

 

 

TAXONOMY  -  Unequal  Cellophane Bee

Order:  Hymenoptera 

Family:  Colletidae (Plasterer and Masked Bees)

Genus:  Colletes (Cellophane bees)

Species:  Colletes inaequalis  (Unequal
     Cellophane Bee)

A female unequal cellophane bee at the entrance of the tunnel leading to her underground nest.

Unequal Cellophane Bee
Colletes inaequalis

1/3"  -1/2" (medium-sized)

A female unequal cellophane bee 

All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography

All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography

The armed cellophane bee emerges very late in the year in the park, around mid-September.  This species is a wildflower pollinator that favors plants in the family Asteraceae.  The bee shown here was found feeding on wild heath aster (Aster ericoides) in the middle of a field of goldenrod.  Armed cellophane bees also have been observed in the park feeding on tickseed and goldenrod. Like the other cellophane bees shown on this guide page, Colletes simulans armatus bees nest in the ground, each female constructing her own solitary tunnel but often residing in close proximity with tunnel-nests built by other bees of the same species.  And like all cellophane bees, the armed cellophane bee lines its nest cells with a waterproofing substance secreted from the bee's Dufour's gland, which solidifies to form a cellophane-like material.

The species Colletes simulans (literally “the imitative cellophane bee”) is divided into several subspecies in the United States.  Among these are Colletes simulans simulans; the Nevada cellophane bee (Colletes simulans nevadensis), found on the West Coast; the Miami cellophane bee (Colletes simulans miamiensis), found exclusively or principally in Florida; and the armed cellophane bee shown here (Colletes simulans armatus), found in the Northeast.  The armed cellophane bee’s name derives from the fact that it has spines on either side of the front of its thorax (a trait shared by other subspecies of Colletes simulans). These spines, however, tend to be well-hidden under the armed cellophane bee’s thorax hair and not always visible to the casual observer.

Identification Traits:  This bee can be identified in part by the time of year in which it appears – very late summer and early fall.  The unequal cellophane bee shown above in this guide page appears in spring; the broad-footed cellophane bee shown at page top emerges in midsummer when tomatillo plants are in bloom. 

 

The armed cellophane bee and the compact cellophane bee (shown directly above) are more likely to be confused with one another because they appear in the park in roughly the same period. The armed cellophane bee, however, differs visibly from the compact cellophane bee:  the armed cellophane bee is bulkier, has a darker appearance and lacks the compact cellophane bee's generally “furry" look and the light-gold coloration of its face and thorax. The hairs on the armed cellophane bee’s thorax are a mixture of dark and grayish white, and sparse enough that the bee’s black integument (“skin”) underneath shows through, adding to the overall darkness of its appearance.

Like the other cellophane bees on this page, the armed cellophane bee has well-defined bands of white hairs encircling its abdomen. As shown in the photo strip at right, the white bands on the top of the bee’s second and third abdominal segments (T-2 and T-3) are uninterrupted.  In addition, all of the white bands continue onto the armed cellophane bee’s underside.  These two traits help distinguish this species from the similar Colletes nudus – on that species, the abdominal bands on T-2 and T-3 are interrupted and the bands underneath the bee’s abdomen are weakly defined. 

The male armed cellophane bee has a triangular face covered with light hairs.  Long white hairs extend from beneath the bee’s face, under its cheek; these are visible when the bee is viewed from the side.

TAXONOMY  -  Armed  Cellophane Bee

Order:  Hymenoptera 

Family:  Colletidae (Plasterer and Masked Bees)

Genus:  Colletes (Cellophane bees)

Species:  Colletes simulans 
Subspecies:  Colletes simulans armatus
                       (Armed Cellophane Bee)

Armed Cellophane Bee
Colletes simulans armatus

1/3"  - 2/5" (medium-sized)

A male armed cellophane bee

All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography

Compact Cellophane Bee
Colletes compactus

1/3"  -1/2" (medium-sized)

A male compact cellophane bee

Compact cellophane bees are a late-summer species.  They appear in the park at the end of August and early September, feeding on late-blossoming wildflowers such as goldenrod, asters and chrysanthemums.   The male bee shown here was found feeding on goldenrod along sunlit park trails in early September.

Colletes compactus nest in the ground, sometimes showing preference for vertical banks and south-facing or generally sunny slopes.  Female bees leave stacks of excavated dirt called tumuli outside of nest entrances.  The bees construct nests by digging long burrows with side tunnels in which eggs are deposited.  Female bees provision their brood cells with an orange substance made of fermented pollen.  A 1968 study of compact cellophane bees conducted in Westchester County by Jerome G. Rozen, Jr. and Marjorie S. Favreau revealed that compact cellophane bees line their tunnel walls with two layers of waterproof material, an outer fragile layer and a stronger inner layer.

Compact cellophane bees are the specifically-targeted prey of the cuckoo bee, Epeolus pusillus.  According to Rozen and Favreau, this parasitic bee flies into the nest tunnels of compact cellophane bees, where it deposits eggs.  When the cuckoo bee's larvae hatch, they sport long curved mandibles, which they use to destroy cellophane bee eggs.  The Epeolus larvae then devour nest provisions and begin the process of turning into mature bees before the Colletes bees have progressed halfway through their growth process.

 

Identification:   Compact cellophane bees have dark abdomens striped with well-defined white bands of hair.  Their thoraxes have a "furry" look -- they are covered with a mixture of yellowish-white and dark brown hairs. From a distance, viewed with the naked eye, the male bees' thoraxes appear light gold; females' thorax hair is somewhat darker.  Males' faces are covered with pale golden-brown hairs. The hair on the faces of females is a mixture of light and dark gray. Male bees run slightly smaller than females. 

 

These bees resemble the cellophane bees shown above on this guide page. Nonetheless, you are unlikely to confuse the species with each another, because late-summer compact cellophane bees appear in the park long after the spring-emerging unequal cellophane bees have disappeared.

 

A distinctive trait of this species is the bee's long malar space (its cheek, or the distance between the bottom of its eye and its mandible).  In males, this trait is particularly exaggerated and gives the bee's face a delicate, triangular shape that narrows toward the bottom.  Female bees can be identified by two parallel prominent ridges on the underside of the last segment of the abdomen (shown in the photo strip at right). 

TAXONOMY  -  Compact  Cellophane Bee

Order:  Hymenoptera 

Family:  Colletidae (Plasterer and Masked Bees)

Genus:  Colletes (Cellophane bees)

Species:  Colletes compactus  (Compact Cellophane Bee)

All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography

A yellow poplar blossom opening in the last week of May

Thoracic Cellophane Bee
Colletes thoracicus

2/5"  -1/2" (medium-sized)

Thoracic cellophane bees are closely related to the unequal cellophane bees shown above, but emerge  later in the spring. While unequal cellophane bees surface as soon as the snow melts, feeding on maple pollen, Colletes thoracicus bees wait a few weeks longer and emerge to feed on tulip trees (Liriodendron tulipifera).  Also known as yellow poplar, tulip trees blossom in the last weeks of May in our area, leaving a litter of orange-and-green blossoms on forest trails. 

Colletes thoracicus males surface about two weeks earlier than females; females then appear in tandem with the height of the tulip poplar bloom.  The male bee shown here was spied in the second week of May, 2017, in a park meadow bordering a woodland near Swan Lake.  The female bee at second right was found two weeks later, in late May of the same year, in a wooded area located at Stone Barns Center for Food and Agriculture.

 

Colletes thoracicus bees are non-aggressive solitary insects that build individual nests in the ground.  They produce only one generation per year.  Like the other cellophane bees on this guide page, Colletes thoracicus bees line their brood cells with a plastic-like substance secreted from the bees' Dufour's gland, which serves to waterproof their nests.  These bees also give off a citrus-like odor which, according to entomological debates, either has a defensive function or serves to attract mates. 

 

This species is able to copulate in mid-air, and during mating season, both male and female thoracic cellophane bees emit loud buzzing noises. Although they do not act in concert or swarm, when thoracic cellophane bees of large aggregations buzz in unison, they produce a sound similar to that of a beehive.  They are, nonetheless, harmless and highly beneficial pollinators of both native plants and crops.  

Thoracic cellophane bees are native to woodlands, where they tend to nest in bare soil in forest clearings. Their nests often appear in relatively shady areas that receive only a few hours of sun each day.  The female bee shown above right, however, built its nest in an open, sunlit pasture located in the Rockwood Hall section of Rockefeller State Park Preserve.  She was one of a large aggregation of several thousand bees, which occupied an extensive area near the Rockwood Hall foundation in June, 2017.  Colletetes thoracicus bees have been known to build nests in aggregations of more than 100,000 members.  

Thoracic cellophane bees are key pollinators of tulip trees, and highly important to their seed production.  Colletes thoracicus bees additionally pollinate willows and a number of spring-blooming native woodland shrubs, including  holly, serviceberry, chokeberry, chokecherry, Chickasaw plum, huckleberry, longstyle sweetroot and blueberry.  They are also significant pollinators of fruit trees such as apples and plums; and of and caneberries such as blackberries and wineberries.  During late May, female thoracic cellophane bees can be found pollinating cultivated raspberries in the crop fields of Stone Barns Center for Food and Agriculture.

A note on exterminators and cellophane bees:  Colletes thoracicus nesting areas have been reported as reaching larger sizes than those of other cellophane bees on this guide page. Nonetheless, we would recommend leaving the nesting areas of these beneficial insects undisturbed, since they are non-aggressive; because their holes aerate the soil; and because their nesting period is so short-lived.  Colletes thoracicus bees disappear completely by late spring. (It's also kind of entertaining to stand beside their nest areas and to listen to how loud groups of these bees can hum.)  If, however, you desire to curtail the bees' nesting, entomologist S. W. T. Batra recommends planting rye grass over nesting areas. The bees prefer patches of  bare ground, and will not dig holes in established lawns. Insecticide application to nest openings is not effective, because the bees' tunnels do not join underground to form a common hive or nest in the way of yellow jackets and other hornets.  (Thus each application kills only one bee.) Bees' eggs also may be resistant to pesticide. 

Identification:   These are fairly large bees -- females often reach sizes above one-half inch. The one shown here at second right measured 3/5".  Males tend to be slightly smaller.

 

Female Colletes thoracicus have striking rust-orange thoraxes, black abdomens and black legs and antennae.  To the naked eye, female bees' abdomens appear entirely black, without banding, although on close inspection weakly-defined pale and rust-colored hair bands are visible.  The female bees'  faces are covered with some rust-colored hairs.  Both males and females have the heart-shaped faces characteristic of cellophane bees generally. 

Unlike their female counterparts, male Colletes thoracicus bees sport prominent bands of pale hair on their black abdomens. Male thoracic cellophane bees have faces and thoraxes covered with tawny light-gold hairs.  (Their thorax hairs sometimes have a light  orangish cast, but lack the intense rust-red coloration of the females' thoraxes. )  The hairs on the male bees' thoraxes are consistently pale in tone, without intermixed dark hairs -- a trait that helps distinguish them from unequal cellophane bees, shown above on this guide page.  From a distance, male unequal cellophane bees appear yellow-brown with dark abdomens.

TAXONOMY  -  Thoracic Cellophane Bee

Order:  Hymenoptera 

Family:  Colletidae (Plasterer and Masked Bees)

Genus:  Colletes (Cellophane bees)

Species:  Colletes thoracicus  (Thoracic
     Cellophane Bee)

All photos (c) 2014 - 2017 Sharp-Eatman Nature Photography

A female thoracic cellophane bee peering from her nest

A female thoracic cellophane bee perched over a yellow poplar blossom

The four-inch blossom of a yellow poplar in May

A male thoracic cellophane bee

This website's photos and text are protected by registered copyright. All photos are © 2014-2017 Paula Sharp & Ross Eatman, all rights reserved.  To inquire about possible use of photos, see Permissions. 

 

REFERENCES:  For a comprehensive list of references used in compiling this guide, click here:

 8-23-15
 

This female bee is excavating tunnels leading to her nest -- she is using her abdomen to push dirt she has dug up away from her nest's entrance.