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 “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 - Large carpenter bee  - (c) Copyright 2018 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
         
(Parkinson's carpenter bee)

Large Carpenter Bee Species of the National Butterfly Center

Strand's Carpenter Bee

Xylocopa strandi

Family:  Apidae

Size:  22 mm  (female)

Food plants at NBC:  

Firebush

(Hamelia patens)
Family:  Rubiaceae

Turk's cap

(Malvaviscus drummondii)
Family:  Malvaceae

When seen:

September & November 2018  

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

A female Strand's carpenter bee on firebush

Detailed Photographs: 

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 mexicanorm carpenter bee -  (C) Copyright 2019 Paula Sharp

A female Xylocopa mexicanorum on esperanza

Food plants at NBC:  

Esperanza

(Tecoma stans)
Family: Bignoniaceae

Firebush

(Hamelia patens)
Family:  Rubiaceae

Flame Acanthus 

(Anisacanthus quadrifidus)
Plant family:  Acanthaceae

Passionflower 

(Passiflora incarnata)
Plant family: Passifloraceae

When seen:

November 2018,
June-July and October 2019
 

Parkinsonia Carpenter Bee
Xylocopa tabaniformis parkinsoniae

Family:  Apidae

Size:  18- 20 mm  (female & male)

Xylocopa tabanifomis - (c) Copyright 2019 Paula Sharp

A female Parkinson's carpenter bee (Xylocopa tabaniformis parkinsoniae)

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

A male Parkinson's carpenter bee (Xylocopa tabaniformis parkinsoniae)

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

Xylocopa micans - (c) Copyright 2018 Paula Sharp

A female southern carpenter bee (Xylocopa micans)

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, green 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 hairless:  many varieties look a bit like greenish winged ants.  As noted above, small carpenter  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 small carpenter bee of the subgenus Zadontomerus

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)

Small Carpenter Bee Species of the National Butterfly Center

Cobalt Carpenter Bee
or Beautiful Carpenter Bee

Ceratina (Calloceratina) cobalta

Family:  Apidae

Size:  7 mm  (female)

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 carpenter bee, a species of the small carpenter bee genus Ceratina 

WJPEG-Ceratina-F-NBC-#319-Palafoxia-call

A male Texas small carpenter bee on Texas Palafoxia

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.

Permissions and Copyright Information:   All images on this site are (c) Copyright 2018-2019 Paula Sharp and Ross Eatman.  All rights reserved. All photographs are protected by registered copyright.  Please contact Sharp-Eatman Nature Photography for written permission before using any of these images for any purpose. 

Last updated November 2019

 1-15-19