Large Carpenter Bees

by Nicholas Muringani

Order: Hymenoptera (ants, bees, and wasps)

Family:  Apidae (bees)

Genus: Xylocopa (large carpenter bees)

How to identify:

As with most insects, large carpenter bees have six legs and four wings. In North America, they are typically large bees (about one inch in length), comparable in size to bumble bees (Bombus). Both groups have hairy (black and /or yellow) thoraxes and abdomens, but large carpenter bees are glossy on the tops of their abdomens (Cotinis et al., 2023; Donald & Richard, 1970).

Advanced ID: Xylocopa in North America are large (20-26 mm) with pubescent thorax and ventral abdomen. Twelve-segmented antennae. The distance between the eye and mandible is very short (absent malar space). The jugal lobe of the hind wing is either absent or shorter than the submedian cell; the front wing has three submarginal cells, the second of which is triangular (Grissell et al., 2017; Donald & Richard, 1970).

Ecology

Metamorphosis Type: Complete metamorphosis: egg, larva, pupa, adult. Larvae often look very different from adults (e.g., caterpillar and butterfly, maggot and fly)

Geographic Range: Although they are most diverse in tropical regions, large carpenter bees inhabit temperate areas and dry desert environments across every continent except Antarctica (Buchmann & Minckley, 2019).

Habitat: Large carpenter bees typically inhabit forests, woodlands, parks, and gardens, where both flowers and dead wood are readily available. They excavate nests in dead wood (logs, snags, or dead parts of live trees) or bamboo. They may burrow into human-made structures, such as wooden walls or fences, but they prefer unpainted and non-pressure-treated wood (Buchman, n.d.; Potter, 2018).

Social Behavior: There are various levels of “social” behavior in the Hymenoptera order.  

Eusocial (true social) behavior is seen in insects like honey bees and ants, where 

(a) There are overlapping generations (e.g., a queen and her daughters) working together, and the needs of the individual are less important than those of the colony. 

(b) There is a division of labor (a caste system), and not all individuals reproduce.

(c) The colony forms some nest for at least a portion of the year (Elzinga, 2004).

Solitary behavior is seen in more than 90% of bee species in North America. In these bees, an adult female constructs her nest without assistance. She gathers food without help, provisions the nest, lays an egg, and leaves her young to develop on their own. Some individuals may live near each other (sometimes even sharing a tunnel entrance), but each nest belongs to one individual female, somewhat like an apartment building. These species typically only live for a year, and a significant portion of that year is spent as an adult (Xerces, n.d.). 

Large carpenter bees are considered both solitary and “primitively social,” because their behavior lies in between the two categories. They are relatively long-lived for insects (up to three years). The mother constructs her nest and provisions it without assistance. However, she may continue to live in the nest even after her young become adults; furthermore, her female adult offspring may continue to live in the nest for a time, even foraging and providing food to their nest mates. There is no caste system in this species, as each individual is capable of reproducing (Buchman, n.d.).

Trophic Level: Herbivore: consumes plants. Large carpenter bees have a variety of plants that they visit to feed on nectar (Buchman, n.d).

Food: Large carpenter bees consume pollen, and they do this by using their specialized mouthparts. The mouthparts they use first are the mandibles, which they use to cut into flowers. They then use their “tongues” that consist of the galea, labial palp, setae, and glossa, which all work together to extract nectar from plants (Buchman, n.d).

Why should we care?

Human Uses: The decomposition of wood by carpenter bees can contribute to the overall health of the ecosystem. The released nutrients support the growth of plants and other organisms, promoting biodiversity by providing essential resources for various species within the ecosystem (Keasar, 2010).

Pollinators: Large carpenter bees are important pollinators of wildflowers and crops, including (but not limited to) tomatoes, eggplants, blueberries, and cranberries. During this process, large carpenter bees will seek nectar from plants and accumulate pollen on their bodies. As they move from one plant to the next, they help the plants reproduce (Buchman, n.d.; McGlynn, 2009; Keasar, 2010).

Conservation Status: There are no indicators that large carpenter bees are vulnerable, threatened, endangered, or invasive.

How We Can Help:

There are many ways we can support pollinators.

1. 1. Plant a pollinator garden using native plants. Even a small garden can make a big difference, including in urban areas.  Use this website and this Urban Habitat Assessment tool to get started. Arrange your plants in clusters (rather than individual plants separated throughout the garden). Many species are active in the fall, so include plants that flower throughout the season (NJ Division of Fish, Game, and Wildlife, n.d.). 
   2. Leave deadwood (preferably unpainted and non-pressure-treated) in your yard or nearby wood for large carpenter bee nests.
   3. Avoid pesticides in your garden (Xerces Society, n.d.), and purchase more organic foods to support organic farmers. 
   4. Sign the Pollinator Protection Pledge and/or add your garden to the Homegrown National Park, and put up a sign to let others know.  We can make a difference.

Did you know?

• Some flowers (e.g., blueberries, cranberries, tomatoes, eggplants, etc.) have sealed anthers (the parts that hold pollen). These require a special pollination method from specialized bees (and one hoverfly) called “buzz pollination.” The insects (including large carpenter bees) use their strong thoracic muscles to sonicate (vibrate and shake) the anthers, releasing a cloud of pollen (Buchman, n.d; Campanell & Kuzovkina, n.d; Vallejo-Marín, 2018). For more information, see this video: This Vibrating Bumblebee Unlocks a Flower’s Hidden Treasure | Deep Look
• In a typical pollination mutualism, flowers provide nectar, and insects pollinate them. Some flowers are tubular to limit the size of the pollinators; only another small pollinator can visit (rather than a large insect who could be covered in pollen from many other flowers), increasing the likelihood of pollination. However, a number of large insects (like large carpenter bees) developed a special behavior to overcome the flower’s defenses; they bite into the base of the flower tube to drink the nectar. This cheats the mutualism by avoiding pollinating the flower (Boggs, 2022; Irwin et al., 2010).

Images Cited

Photo 1: Judy Gallagher. 2018. Creative Commons License | Link. 

Photo 2: Mefisher. 2019. Creative Commons License | Link 

Photo 3: Judy Gallagher. 2012. Creative Commons License | Link 

Photo 4: Bob Peterson. 2013. Creative Commons License | Link 

Photo 5: Matthew Beziat. 2017. Creative Commons License | Link 

Photo 6: Matthew Lindsey. 2023. Creative Commons License. | Link. 

Photo 7: Johnny N. Dell. 2008. Creative Commons License | Link. 

Photo 8: A. Thom-Wolf. 2019. Creative Commons License | Link.  

Photo 9: Judy Gallagher. (2017). Creative Commons License | Link 

Photo 10: Dane Larsen. (2015). Creative Commons License | Link

Photo 11: Royal Tyler, Monday. 2016. Creative Commons License | Link. 

Photo 12: Judy Gallagher. 2014. Creative Commons License | Link. 

Photo 13: Karen Hine. 2018. Creative Commons License | Link.

Photo 14: Allen Szalanski. 2011. Creative Commons License | Link. 

Photo 15: Ed Phillips. (2016). All Rights Reserved   https://www.flickr.com/photos/ed_phillips/25696114322/ 

Photo 16: Zinni. (2020). Creative Commons License | Link 

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