SHARP-EATMAN
NATURE
PHOTOGRAPHY
Globe Mallow Bee
Diadasia (Coquillettapis) diminuta
Family: Apidae
Size: 6 - 8 mm
Associated plants at NBC:
False spiked mallow
(Malvastrum americanum)
Teabush
(Melochia tomentosa)
Plant Family: Malvaceae
When seen:
September & November 2018
May 2019
DIADASIA CHIMNEY BEES
Diadasia
ID GUIDE TO WILD BEES
OF THE NATIONAL BUTTERFLY CENTER
Mission, Texas
DIADASIA CHIMNEY BEES
Genus Diadasia - Tribe Emphorini
Diadasia are small-to-moderate-sized, often beautiful bees. Most are a tawny color, with abdomens that are either striped with pale bands or covered with pale-gold hairs. Female Diadasia have bushy pollen-collecting hairs on their hind legs and distinctive brushes of long hairs on their forelegs. Males often have elongated hind legs.
Diadasia often appear in popular literature under the name “chimney Bees,” because they build small chimney-shaped turrets outside of their tunnel entrances. The function of these chimneys is debatable. Diadasia have been observed disassembling the chimneys, after egg-laying, and using them to plug nest entrances. Some sources hold that the chimneys prevent flooding; keep debris out of the bees' tunnels; and even serve to discourage invaders such as velvet ants.
Like most of the wild bees in this guide, Diadasia are solitary -- that is, each bee builds and provisions its own nest. Diadasia nests tend to take the form of shallow vertical burrows in the ground. Some Diadasia soften the earth with nectar to make nest-digging easier.
In Texas, Diadasia overwinter in the ground and then emerge during spring blooming periods to begin building nests. Despite their solitary status, many Diadasia species are gregarious and form aggregations (or groups) when nesting. Depending on the species and environmental conditions, Diadasia may nest more than once in a given year.
At the National Butterfly Center, male Diadasia rinconis appear before female bees emerge. Multiple male bees often gather together inside golden prickly poppies in late March, shortly before before Texas prickly pear begins to bloom. Prickly poppy is a good pollen source but produces little nectar. Given that male bees (unlike females) do not gather pollen, male Diadasia probably shelter in the poppies because the large blossoms furnish comfortable resting places and protection from wind and rain. Even after prickly pears are in full bloom in the area, male Diadasia rinconis can be found sleeping in the mornings in yellow prickly poppies at the NBC.
A female Diadasia chimney bee: note the brush of long hairs on the underside of the bee's front femur, a defining trait of female Diadasia.
Male Diadasia rinconis "cactus bees" resting inside a golden prickly poppy
Diadasia and Specialist Plants
Diadasia often appear under such common names as “sunflower bee,” “cactus bee" or "mallow bee." These names reflect the fact that most Diadasia are "oligolectic," or pollen specialists that feed on a narrow range of flora. Thus, particular species of Diadasia become inextricably linked with particular plants. Accordingly, Diadasia enavata is sometimes called “a sunflower chimney bee,” because it pollinates plants of the sunflower family nearly exclusively.
A number of Diadasia species belonging to the subgenus Coquillettapis visit cactus flowers. In Texas, such species include Diadasia rinconis; the very similar Diadasia australis; Diadasia opuntiae; and Diadasia piercei. Some of these are strict cactus specialists and some visit other varieties of flowers. Diadasia pierci, for example, collects pollen predominantly from prickly pear cactus. Diadasia opuntiae, whose Latin name might be translated to “prickly pear chimney bee,” visits sunflowers as well as cactus. Diadasia rinconis and Diadasia australis, perhaps the most common visitors to prickly pear cactus in the the Valley, also visit an array of flowers from several plant families, among them members of the poppy, mallow, aster, pea and verbena families.
Some Texas Diadasia are closely associated with plants of the mallow family. Diadasia tropicalis, for example, is a mallow specialist. Diadasia diminuta (also known as the globe mallow bee), and Diadasia ochracea both visit mallows of many genera, and are most often found in the Valley on mallows. (Neither of these two species is a strict mallow specialist, however; both frequent flowers of other plant families as well.)
In other regions of the United States, there are Diadasia that specialize in varieties of morning glory; aster-family flowers; evening primrose; and clarkia. According to Charles D. Michener's The Bees of the World, Diadasia that specialize on mallow and evening primrose tend to be small, with a covering of "uniform, pale hairs" on their abdomens. By contrast, Diadasia that specialize on cactus or sunflowers tend to be robust and to have "distinctively banded" abdomens.
Where to find Diadasia
Diadasia tend to prefer hard-packed and sandy soils and are most likely to appear in arid grasslands and desert habitats. They are found only in the Americas. There are roughly 45-50 Diadasia species, 25 of which appear north of Mexico. All but one occur west of the Mississippi, and most inhabit the southwestern United States. Within Texas, at least thirteen Diadasia species have been documented.
As a general rule, Diadasia ochracea and the sunflower chimney bee Diadasia enavata are the Diadasia species most likely to be seen at locations distant from the Mexican border. Diadasia ochracea is found in California, Mexico and throughout the southwestern United States. The sunflower chimney bee has the largest distribution of any Diadasia. It ranges from as far north as western Canada, as far west as Washington state and California and as far east as Mississippi. Diadasia tropicalis, by contrast, is found within the United States only near the Mexican border.
A male "cactus bee" (Diadasia rinconis) inside a prickly pear blossom
A male "sunflower bee" (Diadasia enavata)
TAXONOMY OF DIADASIA CHIMNEY BEES
Order: Hymenoptera
Family: Apidae
Subfamily: Eucerinae
Tribe: Emphorini
Genus: Diadasia
Species shown below:
Diadasia diminuta (Subgenus Coquillettapis)
Diadasia enavata (Subgenus Diadasia)
Diadasia ochracea (Subgenus Dasiapis)
Diadasia rinconis (Subgenus Coquillettapis)
Diadasia tropicalis (Subgenus Dasiapis)
Diadasia Species of the National Butterfly Center
Associated plants at NBC:
Texas Prickly Pear
(Opuntia engelmannii)
Plant Family: Cactaceae
Golden Prickly Poppy
(Argemone aenea)
Plant Family: Papaveraceae
When seen:
March - April 2019
Rincon Chimney Bee
Diadasia (Coquillettapis) rinconisFamily: Apidae
Size: 11-12 mm (male); 12 mm (female)
A male Diadasia rinconis
A male Diadasia rinconis on a prickly pear blossom. Males bees of this species are covered with tawny hairs and have pale-green eyes.
A male Diadasia rinconis bee negotiating the petal of a prickly pear blossom.
Male Diadasia rinconis bees resting inside a prickly poppy
A Diadasia rinconis chimney bee in a prickly pear blossom
Close-up of bee
A female Diadasia identified by bee expert Jack Neff as either D. rinconis or D. australis. According to Neff, the author of multiple articles on D. rinconis, female D. riconis and D. australis are impossible to differentiate with the naked eye. Their nests often overlap so that the two similar species are found commingling with one another.
Female Diadasia rinconis/australis differ greatly in appearance from male D. rinconis. The abdomens of females are boldly striped with bands of pale hair. The eyes of the female bees are blue-gray.
Alternate view of female bee
Face of a female Diadasia rinconis / D. australis.
The female bee's jaws are entirely dark.
A male Diadasia rinconis stretching its long legs to negotiate a prickly pear blossom
A female Diadasia rinconis / Diadasia australis chimney bee
A scrum of Diadasia males, commonly called a "beeball".
Photo copyright 2020 John Yochum
The image above, taken by photographer and state park ranger John Yochum, depicts a Diadasia rinconis "bee ball". What is a bee ball?
Male Diadasia rinconis patrol flowers and nest entrances in search of mates. A detailed 1992 study of Diadasia rinconis by Neff and Simpson described males lingering at nest entrances for extended periods, waiting for females to emerge and vying with other males for the opportunity to couple. The nest-side activities of male Diadasi rinconis were intense: they strove to drive rivals from nest holes, to break up mating pairs and and even to couple with other males. As soon as a female bee emerged from her nest, a male bee guarding the entrance would pounce on her.
Where males were abundant, a group of them would pile together into a scrum onto the female. She would emerge between 30 to 90 seconds later with a male riding on her back, buzzing and rubbing legs with her. Known colloquially as “bee balls,” such scrums of male Diadasia rinconis are still a common sight in April in Hidalgo County during prickly pear blooms.
Globe Mallow Bee
Diadasia (Coquillettapis) diminuta
Family: Apidae
Size: 6 - 8 mm
Associated plants at NBC:
False spiked mallow
(Malvastrum americanum)
Teabush
(Melochia tomentosa)
Plant Family: Malvaceae
When seen:
September & November 2018
May 2019
A female globe mallow bee (Diadasia diminuta)
These are small bees covered with pale beige hairs. Females have blue-gray eyes.
Rear view of abdomen of a female Diadasia diminuta
This is a male globe mallow bee. Like their female counterparts, males of this species are covered with light-beige hair and have blue eyes.
Face of a male globe mallow bee
A female globe mallow bee (Diadasia diminuta)
A male globe mallow bee (Diadasia diminuta) on a dime
Ochraceous Chimney Bee
Diadasia (Dasiapis) ochracea
Family: Apidae
Size: 8 mm (female)
Associated plants at NBC:
False spiked mallow
(Malvastrum americanum)
Plant Family: Malvaceae
When seen:
September & November 2018
A female ochraceous chimney bee (Diadasia ochracea)
This is a female Diadasia ochracea. Note that the bee's front femur has a dense brush of long hairs. According to entomologist Charles D. Michener, this is a defining trait of female Diadasia.
Female Diadasia use their front and middle legs to pack pollen onto the scopal hairs of their hind legs. The hind legs of female Diadasia tend to look very bushy.
Note the pale spot near the base of the mandible of this female Diadasia (Dasiapis) ochracea. A defining trait of the subgenus Dasiapis is that all of its members have yellow on the base of the mandibles or the clypeus (the face part above the jaws).
Diadasia ochracea chimney bees are a pale tawny color. Their thorax hairs are so pale as to appear white from some angles.
Tropical Chimney Bee
Diadasia (Dasiapis) tropicalis
Family: Apidae
Size: 7-8 mm (male)
Associated plants at NBC:
Rio Grande Abutilon
(Abutilon hypoleucum)
Spiked Malvastrum
Malvastrum americanum
var. Americanum
Teabush
(Melochia tomentosa)
Plant family: Malvaceae
When seen: April & July 2019
A male tropical chimney bee (Diadasia tropicalis)
A male Diadasia tropicalis sleeping on Rio Grande abultilon: the bee's legs are mostly reddish. This trait helps distinguish this species from Diadasia ochracea, which is very similar and which belongs to the same subgenus (Dasiapis).
A male Diadasia tropicalis: Male and female bees of the subgenus Dasiapis have a pale spot at the base of each jaw.
Front view of a male Diadasia tropicalis
Close-up of the face of the male Diadasia tropicalis: Male Diadasia of the subgenus Dasiapis (such as D. tropicalis and D. ochracea) have pale markings on the clypeus and sometimes on the labrum (the face parts above and between the jaws.)
The pale markings on the face of male D. tropicalis are often not visible in the field, because pale hairs may hide most of the bee's face.
Rear view of the reddish legs and abdomen of a male Diadasia tropicalis.
A male tropical chimney bee
A male tropical chimney bee
Sunflower Bee
Diadasia (Diadasia) enavata
Family: Apidae
Size: 12-15 mm (male & female)
Associated plants at NBC:
Common sunflower
(Helianthus annuus)
Cowpen Daisy
( Verbesina encelioides)
Plant family: Asteraceae
When seen:
November 2018, April 2019
June 2019
A male sunflower chimney bee (Diadasia enavata)
Face of male Diadasia enavata: note that the face is longer than it is wide.
Dorsal view of bee's abdomen and thorax
A female Diadasia enavata
Alternate view of female bee
Female Diadasia enavata have bushy yellow scopal hairs on their hind legs. When covered with sunflower pollen, the female bee's leg hairs appear bright yellow-orange.
A male sunflower bee (Diadasia enavata)
A female sunflower chimney bee (Diadasia enavata)
A female sunflower bee (Diadasia enavata)
CITE THIS PAGE: Sharp, Paula and Ross Eatman. "Diadasia." Wild Bees of the National Butterfly Center of Mission, Texas. 15 Jan. 2019, http://www.wildbeestexas.com. Accessed [day/month/year guide accessed].