SHARP-EATMAN
NATURE
PHOTOGRAPHY
ID GUIDE TO WILD BEES
OF THE NATIONAL BUTTERFLY CENTER
Mission, Texas
LARGE & SMALL CARPENTER BEES
Xylocopa & Ceratina
Large Carpenter Bees
Genus Xylocopa
Large carpenter bees are essential pollinators of tomatoes, eggplants and peppers – crops that cannot be pollinated by honey bees. Plants in the tomato family require vibratile or “buzz "pollination, a skill that large carpenter bees possess -- that is, they vibrate their flight muscles while grabbing hold of flowers, in order to shake pollen from their anthers. Large carpenter bees' size and attendant ability to carry prodigious pollen loads also make them highly effective crop pollinators.
The National Butterfly Center has an unusually diverse array of large carpenter bee species. While many northeastern states, for example, harbor only one species of large carpenter bee (the eastern carpenter), the NBC has several. Some of these are featured below. Two of them (Strand's carpenter bee and Griswold's carpenter bee) are notable for marked sexual dimorphism within a single species. Females tend to be entirely black, while males are covered with golden-brown hairs that make them look a little like flying teddy bears. In many other large carpenter bee species, both males and females are predominantly black.
Nesting behavior and "nectar robbing"
Female large carpenter bees build tubular nests within plant materials or in rotted wood. The bees scrape fibers from the walls of their tunnels to form a kind of particle board used to divide their nests into separate egg chambers. The bees nonetheless do not eat wood; they feed exclusively on pollen and nectar.
One interesting aspect of large carpenter bee behavior is “nectar robbing”. Within most bee species, females are the sole pollen-gatherers, but both male and female bees survive by drinking nectar from blossoms. Because large carpenter bees are so hefty, they have difficulty entering a variety of flowers to obtain nectar. Instead of crawling into a flower with a narrow, tubular neck, a large carpenter bee may use its sharp mouth-parts to slice holes in the base of a blossom – the bee then "steals" nectar by lapping it from the flower's anthers through this hole.
At the National Butterfly Center, large carpenter bees are frequent visitors of plants such as esperanza, scarletbush and Turk's cap, all of which have deep-throated blossoms. On any given day, if you lingered by any of these plants, you might well see large black bees sidling up to the blossoms to engage in nectar robbing.
Some carpenter-bee critics complain that nectar robbing allows carpenter bees to take nectar from flowers without coming into contact with the anthers in a way that leads to pollination. In addition, after a carpenter bee robs nectar from a flower, other pollinators may shun the depleted blossoms. Thus, the "robbed" flower never gets pollinated.
Nonetheless, there is some evidence that nectar robbing actually may boost pollination and aid other pollinator species. Smaller bees, including honey bees, often take advantage of the holes slit into the sides of blossoms by carpenter bees. The holes’ existence encourages multiple trips by such smaller bees to the flowers, leading to increased pollen-gathering.
As shown in the accompanying photo strip, at the National Butterfly Center, green metallic sweat bees often take advantage of holes slit in esperanza blossoms by carpenter bees.
Other studies have shown that this benefit is not reserved for smaller bees alone – butterflies also take advantage of nectar-robbing entrances to gain easier access to flowers.
A female large carpenter bee on a red Turk's cap blossom
A female carpenter bee extracts nectar from an esperanza blossom by using her jaws to cut a hole in the calyx.
After the carpenter bee leaves, an Augochloropsis sweat bee stops to drink nectar through the hole snipped by the carpenter bee.
Smaller sweat bees benefit from a carpenter bee's nectar robbing
TAXONOMY OF LARGE CARPENTER BEES
Order: Hymenoptera
Family: Apidae
Subfamily: Xylocopinae
Tribe: Xylocopini
Genus: Xylocopa
Species shown here:
Xylocopa micans (Southern carpenter bee)
Xylocopa griswoldi (Griswold's carpenter bee)
Xylocopa strandi (Strand's carpenter bee)
Xylocopa tabaniformis parkinsoniae
(Parkinsonia carpenter bee)
Large Carpenter Bee Species of the National Butterfly Center
Strand's Carpenter Bee
Xylocopa strandi
Family: Apidae
Size: 19-22 mm (female)
Food plants at NBC:
Scarletbush
(Hamelia patens)
Family: Rubiaceae
Flame acanthus
(Aniscacanthus quadrifidus var. wrightii)
Family: Rubiaceae
Wax mallow (Malvaviscus arboreus var. drummondii)
Family: Malvaceae
When seen:
Sept. - Nov. 2018-2019
A female Strand's carpenter bee. This bee is found in Mexico and Texas. It is slightly smaller than Griswold's carpenter bee, which also appears at NBC. Strand's carpenter bees are frequently seen hovering around red firebush and Turk's cap in NBC butterfly gardens.
According to entomologist Paul Hurd, the outer teeth on the jaws of a Strand's carpenter bee are narrower than the inner teeth. This feature allows the bees to scrape fibers efficiently from bamboo and related plants. It also helps distinguish Strand's carpenter bee from similar species such as Griswold's carpenter bee shown below.
Carpenter bee species are distinguished in part by the color and degree of iridescence on their wings. This Strand's carpenter bee has dark wings with light hints of blue and purple iridescence.
A male Strand's carpenter bee. Males have green eyes, and brownish hairs cover their heads and bodies. (Photo Copyright 2020 Cin-Ty Lee)
The male bee's wings and tegulae (plates where the wings join the thorax) are brown. (Photo Copyright 2020 Cin-Ty Lee)
The faces of male Strand's carpenter bees have distinctive pale markings. (Photo Copyright 2020 Cin-Ty Lee)
A female Strand's carpenter bee (Xylocopa strandi) on scarletbush
A male Strand's carpenter bee (Photo Copyright 2020 Cin-Ty Lee)
The photographs shown here of a male Strand's carpenter bee were taken at Rice University in Houston, Texas, by photographer Cin-Ty Lee. Within the United States, Strand's carpenter bees are found only in Texas: they range from the border to Harris County. Strand's carpenter bees are principally a neotropical species. They occur throughout Mexico and have been documented as far south as Costa Rica.
Griswold's Carpenter Bee
Xylocopa griswoldi
Family: Apidae
Size: 26 mm (female)
Food plants at NBC:
Silverleaf nightshade
(Solanum elaeagnifolium)
Plant Family: Solanaceae
Wax mallow
(Malvaviscus arboreus var. drummondii)
Plant Family: Malvaceae
Esperanza
(Tecoma stans)
Plant Family: Bignoniaceae
Flame Acanthus
(Anisacanthus quadrifidus var. wrightii)
Plant family: Acanthaceae
Passionflower
(Passiflora incarnata)
Plant family: Passifloraceae
When seen:
September & November 2018
July & October 2019
A female Griswold's carpenter bee. Females are covered entirely with black hairs, and have dark wings with shimmering violet, magenta and blue highlights.This species is generally larger than the Strand's carpenter bee shown in the preceding guide entry, but females of the two species appear nearly identical to the naked eye.
A female Griswold's carpenter bee on esperanza
The tip of the abdomen of a female Xylocopa griswoldi, from above
Sternum (underside of abdomen) of a female Xylocopa griswoldi
A female Xylocopa griswoldi on esperanza
A male Xylocopa griswoldi (Photo Copyright 2022 Beth Willoughby)
A male Xylocopa griswoldi (Photo Copyright 2018 Tripp Davenport)
Male Griswold's carpenter bees differ greatly in appearance from females. Females are black and covered with black hairs, and their wings are dark with purplish -to-magenta highlights. Male Griswold’s carpenter bees are yellowish-orange with reddish-gold hairs and have brown wings with reddish veins. Females have dark faces and dark eyes; males have green eyes and pale-yellow masks. The photographs shown here of male Griswold's carpenter bees were taken by photographers Tripp Davenport and Beth Willoughby. Griswold's carpenter bee is a common visitor to the National Butterfly Center. This species is endemic to southeastern Texas, northeastern Mexico and the eastern slope of the Gulf of Mexico.
Food plants at NBC:
Esperanza
(Tecoma stans)
Family: Bignoniaceae
Retama
(Parkinsonia aculeata)
Family: Fabaceae
Scarletbush
(Hamelia patens)
Family: Rubiaceae
Flame acanthus
(Anisacanthus quadrifidus var. wrightii)
Plant family: Acanthaceae
Passionflower
(Passiflora incarnata)
Plant family: Passifloraceae
Guayacan
(Guaiacum angustifolium)
Family: Zygophyllaceae
When seen:
Nov. 2018
June-July & Oct.-Dec. 2019
Feb. 2020
Parkinsonia Carpenter Bee
Xylocopa tabaniformis parkinsoniae
Family: Apidae
Size: 18- 20 mm (female & male)
A female Xylocopa tabaniformis of the subspecies parkinsoniae. Bees of the species X. tabaniformis are sometimes called "Horsefly-like carpenter bees". Female bees of this handsome subspecies, however, do not really resemble horseflies.
This is Parkinsonia aculeata, the plant after which this bee was named. This flowering tree is known locally as retama.
Parkinsonia carpenter bees have bold, interrupted bands of white hair on their abdomens.
A male Xylocopa tabaniformis parkinsoniae -- males have bug eyes, a trait that makes them resemble horseflies somewhat.
Like the females, males of this species have black abdomens banded by white hairs.
Close-up of male bee's abdomen, from behind.
A female Parkinsonia carpenter bee (Xylocopa tabaniformis parkinsoniae)
A male Parkinsonia carpenter bee (Xylocopa tabaniformis parkinsoniae)
This carpenter bee subspecies sometimes appears mislabeled under the common name “Parkinson’s carpenter bee,” presumably a mistranslation of the bee’s Latin name, Xylocopa tabaniformis parkinsoniae. The subspecies name “parksinsonae” does not derive from a person named Parkinson, but instead from the plant Parkinsonia aculeta, known in the Lower Rio Grande Valley as retama. This bee was named by Wilmatte Cockerell, who included the first decription of the subspecies in her 1917 publication “Collecting Bees in Southern Texas”. Cockerell found the bee feeding on Parkinsonia aculeta.
The Parkinsonia carpenter bee subspecies is a member of the species Xylocopa tabaniformis, sometimes collectively referred to as horse-fly like carpenter bees. This species contains more than ten subspecies of varying appearances, all found within North, Central and South America. Of these, only the Parkinsonia carpenter bee is endemic to the Lower Rio Grande Valley. Two other subspecies of X. tabaniformis occur within the United States – X. tabaniformis orpifex and X. tabaniformis androleuca. Both of these are predominantly black and lack the distinctive pale bands found on X. tabaniformis parkinsoniae.
Parkinsonia aculetata, the plant after which this carpenter bee subspecies was named
Southern Carpenter Bee
Xylocopa micans
Family: Apidae
Size: 15-19 mm (female);
16-19 mm (male)
Food plant at NBC:
Flame Acanthus
(Anisacanthus quadrifidus
var. wrightii)
Mexican shrimp plant
(Justicia brandegeana)
Plant family: Acanthaceae
When seen:
September 2018
June-July and October 2019
March 2020
A male southern carpenter bee
Alternate view of a male southern carpenter bee
The bee's thorax hairs are golden brown, and its abdomen is black.
A female southern carpenter bee (Xylocopa micans): although these are common throughout parts of the southern United States, they are relatively uncommon at the National Butterfly Center, where Xylocopa griswoldi (Griswold's carpenter bee) predominates.
The thorax of a southern carpenter bee: note the white hairs rimming the back of the bee's thorax
Close-up of pits on the bee's trhorax
A male southern carpenter bee (Xylocopa micans)
Face of a male southern carpenter bee (Xylocopa micans)
A female southern carpenter bee (Xylocopa micans)
Cobalt small carpenter bee
Ceratina (Calloceratina) cobalta
Family: Apidae
Size: 7-8 mm
Food plants at NBC:
Alamo vine
(Mirremia dissecta)
Family: Convolvulaceae
When seen:
November 2018
A female Ceratina cobaltina curled around the anthers of an alamo vine flower
The bee's abdomen bells out near the back and narrows abruptly at the tip, a trait common to small carpenter bees.
Ceratina cobaltina are a bright blue-green.
A male Ceratina cobaltina: like the females, males of these species are a brilliant blue-green. (Photo: Copyright 2020 Victor Engel)
A male Ceratina cobaltina from behind: note the raised ridge on the back of the bee's head, a characteristic of Ceratina generally. (Photo: Copyright 2020 Victor Engel)
Face of a male Ceratina cobaltina. Flanked by two ivory triangles, an inverted pale T covers the lower half of the bee's face. The bases of the bee's jaws are also pale. (Photo: Copyright 2020 Victor Engel)
A female Ceratina cobaltina gathering pollen from an alamo vine flower
A male Ceratina cobaltina emerging from a blossom. (Photo Copyright 2020 Victor Engel)
The photographs of the male Ceratina cobaltina shown here were taken in Austin in March 2020 by photographer Victor Engel. Ceratina cobaltina is a neotropical species endemic to Mexico. It was first documented in Hidalgo County in 1970, and has since moved northward in Texas. The bee is believed to have arrived in Austin's Travis County as an adventive species transported on firewood.
Texas Small Carpenter Bee
Ceratina (Zadontomerus) texana
Family: Apidae
Size: 5 mm (male)
Food plants at NBC:
Texas palafox
(Palafoxia texana)
Family: Asteraceae
When seen:
November 2018
A male Texas small carpenter bee (Ceratina texana) on Texas palafox
A male Texas small carpenter bee on Texas palafox.
The male bee has a distinctive pale mark on its clypeus described by entomologist H. V. Daly as "hat-shaped". The male bee's labrum is also pale, with dark dots on either side. The bee's face is heavily pitted.
Dorsal view of bee. A hallmark trait of males of this small species is the reddish coloring of the tarsi (lower leg segments).
This is a female Ceratina texana. Small carpenter bees of the subgenus zandotomerus are weakly metallic. Pale markings on the female bee shown here are confined to the face, legs and pronotum.
The female Texas small carpenter bee has a bell-shaped ivory mark on its clypeus, and its face is heavily pitted. Its lower legs are reddish.
Dorsal view of bee
Face of a male Texas small carpenter bee,
with its characteristic pale "hat-shaped" mark.
A female Texas small carpenter bee
SMALL CARPENTER BEES
Genus Ceratina
Most people think of carpenter bees as the large, black-bodied bees that tunnel through wood, like those shown above on this guide page. Carpenter bees, however, also include an array of small, greenish bees of the genus Ceratina, which are key pollinators of a vast range of garden plants and commercial crops.
Given that they are so different in size and general appearance, why do small and large carpenter bees share the same name? Both possess qualities common to their subfamily Xylocopinae.
According to Charles D. Michener, author of the 953-page The Bees of the World, both small and large carpenter bees engage in the practice of storing food for adult bees, rather than for young only. Such behavior is unusual in the bee world. Small and large carpenter bees also share distinctive physical characteristics: among others, both have faces that are are flat in front.
Behavior of small carpenter bees
Small carpenter bees construct nests in burrows within dead wood or plant material, creating dividers for egg chambers by scraping fibers from tunnel walls. These pollinators do not bore holes in wooden parts of buildings like many large carpenter bees and are not considered pests. Instead, small carpenter bees build solitary nests in the dead stems of pithy plants.
Ceratina of North America generally range from about 8 millimeters long to less than half that length. Because of their diminutive size, small carpenter bees are able to enter small-mouthed flowers unreachable by larger bees. Females carry pollen on brushes located on their hind legs.
Identifying traits:
Small carpenter bees are slender and relatively hairless: many varieties look a bit like greenish winged ants. As noted above, small carpenter bees have flat faces; they also have dark, short antennae. Many small carpenter bees have abdomens that bell outward in the middle and taper abruptly at the end, giving them a club-shaped appearance.
There are 24 documented species of small carpenter bees in the United States and Canada; at least 13 are found in Texas. They include several species in the subgenus Zadontomerus shown in the accompanying photographs. This subgenus includes, among others, the Texas small carpenter bee found at the National Butterfly Center and featured below.
In most of the country, Ceratina are small, dark-green bees, easy to overlook, despite the fact that they are ubiquitous, energetic pollinators of backyard flower gardens. In the Lower Rio Grande Valley, however, Ceratina can be far more conspicuous, in the way of neotropical insects. Cobalt small carpenter bees, found at the National Butterfly Center, are impossible to miss: they are brilliant blue-green and look like jewels resting in the mouths of flowers.
Most Ceratina are dark green, and so small that they easily escape notice.
This carpenter bee is a mere 7 mm long.
TAXONOMY OF SMALL CARPENTER BEES
Order: Hymenoptera
Family: Apidae
Subfamily: Xylocopinae
Tribe: Ceratinini
Genus: Ceratina
Subgenus: Calloceratina
Species shown below:
Ceratina cobaltina (cobalt small carpenter bee)
Subgenus: Zandontomerus
Species shown below:
Ceratina texana (Texas small carpenter bee)
Small Carpenter Bee Species of the National Butterfly Center
CITE THIS PAGE: Sharp, Paula and Ross Eatman. "Ceratina and Xylocopa." Wild Bees of the National Butterfly Center of Mission, Texas. 15 Jan. 2019, http://www.wildbeestexas.com. Accessed [day/month/year guide accessed].