Eastern carpenter bee

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Eastern Carpenter Bee
Carpenter bee.jpg
Female Xylocopa virginica on Salvia
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Apidae
Subfamily: Xylocopinae
Genus: Xylocopa
Subgenus: (Xylocopoides)
Species: X. virginica
Binomial name
Xylocopa virginica
Linnaeus, 1771
  • X. v. krombeini
  • X. v. texana
  • X. v. virginica

The Xylocopa virginica, more commonly known as the eastern carpenter bee, extends through the Eastern United States and into Canada. They nest in various types of wood and eat pollen and nectar.[1] The eastern carpenter bee differs from other bee species in that it does not have a queen. While typically bees have one queen which primarily reproduces and allows the workers to forage, in Xylocopa virginica, this method is replaced by a system in which dominant females are responsible for reproduction, foraging, and nest construction.[2]

Description and Identification[edit]

Female X. virginica

The bee is similar in size to bumblebees, but has a metallic, mostly black body with a slight purple tint.[3]The X. virginica males and females have generally the same mass, but can be differentiated visually by the male's longer body and the female's wider head. Additionally, the males have larger thoracic volumes for given masses. [4] Females of different social standing can also be told apart based on morphology. Primary females are larger than secondary or tertiary females, and additionally primary females have more mandibular and wing wear.[1]

Taxonomy and Phylogeny[edit]

X. virginica belongs to the genus Xylocopa, which consists of over 400 species.The distribution of the genus Xylocopa stretches over most continents. They are usually found in tropical and subtropical climates,[5] while X. virginica is found mostly in temperate climates.[1]

Distribution and Habitat[edit]

The eastern carpenter bees belong to temperate and cold zones.[1] Because X. virginica builds its nests in wood structures, it is common for them to nest in constructed furniture or buildings.[6] The X. virginica is the most common large carpenter bee in North America, and they nest in small groups, so their nests are fairly common.[4]

The primary difference in the appearances of a bumblebee and X. virginica is the conspicuous black, round spot surrounded by yellow hairs atop the thorax.


X. virginica build their nests in wood, bamboo culms, agave stalks, and other comparable materials, but they prefer to nest in milled pine or cedar lumber. The nests are built by scraping wood shavings off of the wall. These shavings are then used to create partitions between plant cells. The entrance cuts into the wood perpendicular to the grain, but they are built parallel beyond the entrance. These nests may be either social, containing groups of two to five females, or solitary. Social nests are more common, despite the fact that brood productivity is actually lower when females choose to nest together[2]

The nests are usually round and have an average of 1-4 tunnels.[1] They have multiple branches with each adult female living and laying eggs in a separate branch, but females share one common entrance. Because the nests are extremely costly to build, it is common for females to try to reuse old nests.[2]

The female bee pushes castings out of the entranceway and maintains the hibernaculum.
The Eastern Carpenter Bee


Carpenter bees are not solitary bees, but are not truly social either. The weak form of sociality they exhibit, with one female doing the majority of the work, and caring for her sisters, may be a transitional step in the evolution of sociality.[7]

Dominance Hierarchy[edit]

Female X. virginica can have solitary nests, but they usually nest in social groups. The social order of X. virginica is broken into three groups: primary, secondary, and tertiary. Primary females act as the dominant within a nest and are in charge of reproduction, providing food for the larvae, and laying all the eggs. This is different from many bee species in which there is a queen that focuses her energy solely on laying eggs while relying on provisions provide by subordinate bees. Secondary females may sometimes participate in oviposition, and they reinforce this potential role by helping provide for the larvae or performing nest maintenance. Tertiary females rely on the provisions provided by primary females and quietly await overwintering while remaining inactive.[2]

Studies have shown that primary females are usually the bees that have overwintered twice, while tertiary bees have only overwintered once. Tertiary bees will most likely survive a second overwintering to become primary female the following year. Secondary bees may survive a second winter, but that is unlikely if they actively forage after their first overwintering.[2]

Division of Labor Among the Sexes[edit]

Not all females do the same work in a social nest. This is evident based on the varying levels of wear on the wings and mandibles of females of various social standing. Although many nests have more than one female, it is usually the older, primary female who will perform the nesting activities, such as digging and lining the cells.[1]

Males often have long period of hovering flying or fast pursuit of intruders while females flight activity is usually very directed, such as flights to flowers and food sites. Larger females have an advantage because they can carry larger amounts of pollen or nectar back to the nest and can fly longer distances.[4]


X. virginica survive mostly on honey and pollen. Newly emerged bees don’t have food stored in their nest, but they are occasionally brought honey.[1]

Nectar Robbing[edit]

Carpenter bees have been known to exhibit nectar robbing behavior. This happens when the bee pierces the corolla of long tubed flowers, thus accessing nectar without making contact with the anthers - thus bypassing pollination. In some plants this reduces fruit production and seed number. In other plants, defensive mechanisms have allowed for pollination to occur despite corollary perforation.[8]

Mating Behavior[edit]

Each nest usually has one mated individual.[1] Mating occurs in April and is often accompanied by a bobbing dance that involves about a dozen males and only a few females.[6]

Males require female activity, specifically flight, in mating. Occasionally before mating, the couple will face each other and hover for a few minutes. When the male contacts the female, he mounts her back and attempts to push his abdomen under hers. Copulation occurs at this instant, and it is almost always followed by more mating attempts. If, during copulation, the female lands, the couple will disengage and the male will hover waiting for the female to take flight again.[1]

Larger males are usually more successful in mating. Because of their competitive advantage due to their size, males will likely claim a territory near female nest sites. Smaller males will stay at foraging sites or other areas they think females may pass so they can mate with reduced competition.[4]

Kin Selection[edit]

Research has shown that, regardless of sex, X. virginica show more aggression toward non-nestmates than nestmates, indicating that they can recognize each other. By living in social groups with inclusive fitness, offspring can be raised with the help of the nest community rather than in solitary.[9]

The ability of X. virginica to recognize housemates allows primaries and secondaries to exclude tertiary bees from their nests. Tertiary bees are a burden on resources because they don’t perform any useful activities, but they benefit from the food and shelter provided by the primary females.[2]

Life Cycle[edit]

Eggs are laid starting farthest from the exit hole. Researchers suggest that there is a mechanism that synchronizes the emergence time of young that are laid at different times by causing the younger eggs to develop faster. This mechanism prevents bees that would emerge sooner from removing their siblings and decreasing their potential competition.[1]

Bees that have newly emerged have a soft cuticle and white wings. The wings later transition to brown, then to a bluish black. The larvae learn to fly only 3–4 days after emergence, but they remain in their nest for at least two weeks. These larvae eat honey but not pollen, and will develop within one month. Between the larvae and adult stage, there is a juvenile stage in which the bees remain in their nest and are usually found among siblings.[1]


Territorial Behavior in Males[edit]

Males will establish territories near an active nest entrance. For males that are near the nest entrance, their boundaries are usually linear and several meters long. For males that are farther from the exit, their boundaries are usually in the shape of a square and shorter in length. Males can stay in one territory for as long as two weeks. Although they do most of their foraging and resting during the night, they take small breaks throughout the day as well. After these breaks, they often have to fight off intruders that have taken advantage of their absence.[1]

Flight near the nest are usually uniform and involve a lot of hovering. Flights protecting their territory could be as short as a few minutes, but may extend beyond an hour. Studies have shown a fascinating pattern in territory protection. Males won’t notice another individual unless they are flying at high speeds. When other individuals hover near the nest, it is highly unlikely that the male will pursue, whereas, if another male comes into a territory at a high speed, the territorial male will chase after him.[1]


Female eastern carpenter bees have glands that allow them to mark the entrances of nests. Males also have these glands, and they are in equal size, but they produce no marking substance.[1]


The male bee is unable to sting, though they will commonly approach human beings, especially if they wave or move parts of their body. The female, on the other hand, will sting if provoked[10] While the pain level of these stings is not well-documented, researchers have testified that X. virginica will sting if handled.[6]

Human Importance[edit]


X. virginica has many advantages acting as crop pollinators. Their active seasons are quite long, and the forage on a wide variety of plant species. Also, because the start of their activity season is dependent on temperature, it is very easy for greenhouse workers to manipulate the beginning of foraging activity.[11] However, in comparison to species such as the honey bee, their smaller nest makes them less powerful as pollinators.[12]

Destructive Behavior[edit]

Because X. virginica builds its nests in various types of wood, it presents the disadvantage of weakening wood in manmade structures. They are also able to produce an excrement upon exiting their tunnels that may splash on the sides of buildings and negatively affect the aesthetic appeal of that structure. However, when weighed against the benefits X. virginica has as pollinators, this problem is easily overlooked.[6]

Eastern carpenter bee pollinating a bull thistle flower

Further reading[edit]

  • Mitchell, Theodore B. (1962): Bees of the Eastern United States. Vol. II, The North Carolina Agricultural Experiment Station, Tech. Bul. No.152, pp. 557 (p. 507 ff)
  • Balduf WV, 1962. Life of the carpenter bee, Xylocopa virginica (Linn.) (Xylocopidae, Hymenoptera). Annals of the Entomological Society of America 55:263-271.
  • Barrows EM, 1983. Male Territoriality in the Carpenter Bee Xylocopa virginica. Animal Behaviour 31: 806-813.
  • Barthell JF, Baird TA, 2004. Size variation and Aggression among Male Xylocopa virginica (L.) (Hymenoptera: Apidae) at a Nesting Site in Central Oklahoma. Journal of the Kansas Entomological Society 77:10-20.
  • Gerling D, Hermann HR, 1976. Biology and Mating Behavior of Xylocopa virginica L. (Hymenoptera, Anthrophoridae). Behavioral Ecology and Sociobiology 3:99-111.
  • Sabrosky CW, 1962. Mating in Xylocopa virginica. Proceedings of the Entomological Society of America 64:184.
  • Rau,Phil, 1933. The Jungle Bees and Wasps of Barro Colorado Island: with notes on other insects, Chapter VIII: The Behavior of the Great Carpenter Bee, Xylocopa virginica with notes on the genesis of certain instincts.


  1. ^ a b c d e f g h i j k l m n Gerling, Dan; Hermann, Henry R. (1978-06-01). "Biology and mating behavior of Xylocopa virginica L. (Hymenoptera, Anthophoridae)". Behavioral Ecology and Sociobiology 3 (2): 99–111. doi:10.1007/BF00294984. ISSN 0340-5443. 
  2. ^ a b c d e f Richards, Miriam H. (2011-06-14). "Colony Social Organisation and Alternative Social Strategies in the Eastern Carpenter Bee, Xylocopa virginica". Journal of Insect Behavior 24 (5): 399–411. doi:10.1007/s10905-011-9265-9. ISSN 0892-7553. 
  3. ^ Grissell, E.E. (July 1999). "Large Carpenter Bees, Xylocopa spp. (Insecta: Hymenoptera: Apidae: Xylocopinae)" (PDF). UF/IFAS. 
  4. ^ a b c d Skandalis, Dimitri A.; Tattersall, Glenn J.; Prager, Sean; Richards, Miriam H. (2009-01-01). "Body Size and Shape of the Large Carpenter Bee, Xylocopa virginica (L.) (Hymenoptera: Apidae)". Journal of the Kansas Entomological Society 82 (1): 30–42. doi:10.2317/JKES711.05.1. ISSN 0022-8567. 
  5. ^ Leys, Remko; Cooper, Steve J. B.; Schwarz, Mike P. (2002-10-01). "Molecular phylogeny and historical biogeography of the large carpenter bees, genus Xylocopa (Hymenoptera: Apidae)". Biological Journal of the Linnean Society 77 (2): 249–266. doi:10.1046/j.1095-8312.2002.00108.x. ISSN 1095-8312. 
  6. ^ a b c d Balduf, W. V. (1962-05-01). "Life of the Carpenter Bee, Xylocopa virginica (Linn.) (Xylocopidae, Hymenoptera)". Annals of the Entomological Society of America 55 (3): 263–271. doi:10.1093/aesa/55.3.263. ISSN 0013-8746. 
  7. ^ "Eastern Carpenter Bee". Encyclopedia of Life. Retrieved 5 April 2015. 
  8. ^ "Large Carpenter Bees as Agricultural Pollinators". www.hindawi.com. Retrieved 2015-10-01. 
  9. ^ Peso, Marianne; Richards, Miriam H. (2010-03-01). "Knowing who's who: nestmate recognition in the facultatively social carpenter bee, Xylocopa virginica". Animal Behaviour 79 (3): 563–570. doi:10.1016/j.anbehav.2009.11.010. 
  10. ^ "Carpenter Bees (Entomology)". Entomology (Penn State University). Retrieved 2015-10-01. 
  11. ^ "Large Carpenter Bees as Agricultural Pollinators". www.hindawi.com. Retrieved 2015-09-27. 
  12. ^ Dukas, Reuven; Real, Leslie A. (1991-08-01). "Learning foraging tasks by bees: a comparison between social and solitary species". Animal Behaviour 42 (2): 269–276. doi:10.1016/S0003-3472(05)80558-5. 

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