ID GUIDE TO WILD BEES
OF THE NATIONAL BUTTERFLY CENTER

Mission, Texas

LARGE  &  SMALL  CARPENTER  BEES
Xylocopa  & Ceratina

Strand's Carpenter Bee

Xylocopa strandi

Family:  Apidae

Size:  19-22 mm  (female)

Food plants at NBC:  

Firebush

(Hamelia patens)
Family:  Rubiaceae

Turk's cap

(Malvaviscus drummondii)
Family:  Malvaceae

​When seen:

Sept. - Nov.  2018-2019 

Xylocopa strandi - Strand's Carpenter Bee - (c) Copyright 2018 Paula shrp

A female Strand's carpenter bee on firebush

Xylocopa strandi; Strand's carpenter bee; Copyright 2020 Cin-Ty Lee

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.

 

Mexican Carpenter Bee

Xylocopa mexicanorum

Family:  Apidae

Size:  26 mm  (female)

Food plants at NBC: 
 

Silverleaf nightshade

(Solanum elaeagnifolium)
Plant Family:  Solanaceae

Turk's cap

(Malvaviscus drummondii)
Plant Family:  Malvaceae

Esperanza

(Tecoma stans)
Plant Family: Bignoniaceae

Flame Acanthus 

(Anisacanthus quadrifidus)
Plant family:  Acanthaceae

Passionflower 

(Passiflora incarnata)
Plant family: Passifloraceae

When seen:

September & November 2018
July & October 2019
 

Xylocopa mexicanorum; Mexican carpenter bee - (c) Copyright 2019 Paula Sharp

A female Xylocopa mexicanorum on esperanza

Xylocopa mexicanorum; Mexican carpenter bee male; Copyright 2018 Tripp Davenport

A male Xylocopa mexicanorum   (Photo Copyright 2018 Tripp Davenport)

Male  Mexican carpenter bees differ greatly in appearance from females.  Females are entirely black with dark, iridescent wings, while males are covered with reddish gold hairs and have brown wings.  Females have dark faces and dark eyes; males have green eyes and pale-yellow masks.  The photograph shown here of a male Mexican carpenter bee was taken by photographer Tripp Davenport at the National Butterfly Center in July, 2018.

 

Food plants at NBC:  

Esperanza

(Tecoma stans)
Family: Fabaceae

Retama

(Parkinsonia aculeata)
Family:

Firebush

(Hamelia patens)
Family:  Rubiaceae

Flame Acanthus 

(Anisacanthus quadrifidus)
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)

Xylocopa tabaniformis parkinsoniae; Parkinsonia carpenter bee; Parkinson's carpenter bee; (c) Copyright 2019 Paula Sharp

A female Parkinsonia carpenter bee (Xylocopa tabaniformis parkinsoniae)

Parkinsonia carpenter bee - Xylocopa tabaniformis parkinsoniae - (c) Copyright 2019 Paula Sharp

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 first described 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 aculeata; Retama; Copyright 2020 Paula Sharp

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

Xylocopa micans southern carpener bee; (c) Copyright 2020 Paula Sharp

A male southern carpenter bee (Xylocopa micans)

Xylocopa micans southern carpener bee; (c) Copyright 2020 Paula Sharp

Face of a male southern carpenter bee (Xylocopa micans)

Xylocopa micans - (c) Copyright 2018 Paula Sharp

A female southern carpenter bee (Xylocopa micans)

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 “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 the Mexican 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 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 yellow esperanza and red firebush 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 pollen-gathering. 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 considerable 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 photo strip at right, 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.

Xylocopa mexicanorum; Mexican carpenter bee - (c) Copyright 2019 Paula Sharp

A female large carpenter bee on a red Turk's cap blossom

Smaller sweat bees benefit from a carpenter bee's nectar robbing

TAXONOMY OF LARGE CARPENTER  BEES

Order:   Hymenoptera

Family:   Apidae

Subfamily:  Xylocopinae

Genus:   Xylocopa

Species shown here: 
    Xylocopa micans (Southern carpenter bee)
    Xylocopa mexicanorum (Mexican carpenter bee)
    Xylocopa Strandi (Strand's carpenter bee)
    Xylocopa tabaniformis parkinsoniae
         
(Parkinsonia carpenter bee)

Large Carpenter Bee Species of the National Butterfly Center

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 at right.  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 Ceratina, 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.

A female Texas small carpenter bee

TAXONOMY OF SMALL CARPENTER  BEES

Order:   Hymenoptera

Family:   Apidae

Subfamily:  Xylocopinae

Genus: Ceratina

Subgenus:  Calloceratina (Beautiful ceratina) 

Species shown below: 
    Ceratina cobaltina (Cobalt Ceratina)

Subgenus:  Zandontomerus

Species shown below: 
    Ceratina texana (Texas small carpenter bee)

Cobalt Ceratina
or Beautiful 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

Cobalt ceratina - Ceratina cobalta - (c) opyright 2018 Paula Sharp

A female cobalt ceratina gathering pollen from an alamo vine flower

Ceratina cobaltina male - (c) Copyright 2020 VIctor Engel

A male cobalt ceratina emerging from a blossom.   (Photo Copyright 2020 Victor Engel)

The photographs of the male cobalt ceratina 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

Ceratina texana small carpenter bee - (c) Copyright 2019 Paula Sharp

A male Texas small carpenter bee on Texas palafox

Ceratina texana small carpenter bee - (c) Copyright 209 Paula Sharp

Face of a male Texas small carpenter bee,

with its characteristic pale "hat-shaped"  mark.

Ceratina ; (c) Copyrigt 2020 Paula Sharp

A female Texas small carpenter bee

Small Carpenter Bee Species of the National Butterfly Center

All images protected by registered copyright.
  Permissions Information

 

Last updated June 2020

 1-15-19