Valley Carpenter Bee: Facts & Behaviors

When you first encounter the Valley Carpenter Bee, it can be frightening. The bees are large, the whole genus of them is. They are about a third as long as a hummingbird.

Metallic black, bulky, inch-long females buzz like black helicopters, humming from flower to blossom. Do you want to find out more? keep reading to find out more!


How Do I Describe the Valley Carpenter Bee?

Valley Carpenter Bee
Picture of a Valley Carpenter Bee

When you first encounter the Valley Carpenter Bee, it can be frightening. The bees are large, the whole genus of them is. They’re about a third as long as a hummingbird.

Metallic black females, inches long, hum like black helicopters, humming from flower to blossom. Rarely seen males are golden, fuzzy and have gold-green eye colour.

The Valley Carpenters are the largest bee in California. They are often called “black bumblebees”, but they are distant cousins of bumblebees, just like honeybees.

Males lack stingers, but females are aggressive and will sting when provoked. The males have a large thoracic pheromone gland that produces pheromones to attract females.


Read also: Do Carpenter Bees Sting?


Where is the Habitat of the Valley Carpenter Bee?

The primary habitats of mainland X. sonorina are:

  • Valleys
  • Foothills with deciduous trees dominated by oaks

It is believed that humans helped this species colonize the Pacific islands.

When X was introduced to the Hawaiian Islands is unknown. Sonorina may have been introduced to the Hawaiian Islands before 1874 when British entomologist Frederick Smith first named the species.

Sonorina can be found in all the main Hawaiian Islands, as well as the Mariana Islands. In tropical agriculture, X. Sonorina is used to pollinate Passiflora Edulis, which is a passion fruit species.

Hawaii is located in the Pacific Ocean more than 2,000 miles (3,219 kilometres) from the nearest landfall in North America. This distance is too great for biological dispersal by natural means. It has been suggested, therefore, that humans may have helped X. Sonorina was the species that brought X to Hawaii.

After the colonization of Hawaii, X. Sonorina was also introduced to the Mariana Islands, China and Japan but it did not succeed.

Anecdotally, the species has been reported on Midway Atoll as well as in Java, New Guinea and the Philippines. However, only Midway records have specimens that confirm the report.

The two species are:

  • Xylocopa darwini: is found in the Galápagos Islands, 604 mi (972 km) west of South America, with the mainland of Ecuador as the closest land mass.
  • Xylocopa clarionensis: found on Clarión Island in the Revillagigedo Islands, 700 mi (1,127 km) from the coast of Mexico. X. clarionensis is thought to be most closely related to Xylocopa sonorina.


How Do I Describe the Lifecycle of the Valley Carpenter Bee?

In the spring females may mate with the males, then disperse to start new nests or clean and enlarge old tunnels that were used in the winter. The larvae are fed by a mixture called “beebread” in each cell of the female provision.

Each cell is separated with a sawdust partition and an egg is placed on top of the pollen mass. During the winter, young adult male bees and females hibernate within the tunnels.


How Do I Describe the Behavior of the Valley Carpenter Bee?

How Do I Describe the Behavior of the Male Valley Carpenter Bee?

The males of Sonorina X. Sonorina appear to optimize their mate-finding activity by the predictions of the ideal free distribution theory.

The theory goes that those who are fittest will try to occupy the territory with the greatest amount of resources, while others will occupy a territory that is lacking in resources until both areas are occupied.

Species like X. Sonorina have patches with different qualities resulting from “the constant but variable input of females searching for mates over afternoons and during flight seasons”.


How Do I Describe the Pheromones of the Male Valley Carpenter Bee?

The large mesosoma X gland is located in male X. Sonorina produces volatile components called pheromones that are attractive to women. These pheromones have a long-range attraction and are used to advertise males.

The gland is only active during the season and males overwintering do not have any detectable attractant. The pheromones are used by sonorina to mark the centre of their territory.


Read also: What Do Carpenter Ants Eat?


How Do I Describe Territoriality In Male Valley Carpenter Bees?

It is unlikely that a male will meet a female, so it would be beneficial for both sexes if the male produced attractants.

Attractants can be male signals, such as a loud buzzing or the addition of odours to flowers. These signals may be used by males when they patrol along long paths or hover at a particular site.

The female may react by choosing among the males. Males can produce quantitatively and qualitatively different pheromones that reflect their fitness.

Males can use pheromonal signals to move their territory from the resource site to prominent locations such as trees, hills, and other protrusions.

Pheromones can direct the female to the territory established by the males. The female bees will mark their signal at a short distance to attract them towards the male territory, just before they copulate.

The competition between males to gain access to non-resource areas may result in adaptations which continue to evolve, until one male gains an advantage.

X is affected by a variety of factors. sonorina fidelity rates. First, a high mortality rate of male residents is significantly associated with frequent turnover and decreased site loyalty.

The second factor is the density of males. The competition for territory control increases as the ratio of rivals and suitable territories increases.

For X. Sonorina’s low territorial occupancy and high male density on a few “lek” days resulted in a decrease in fidelity.

The quality of territorial sites is another aspect that influences site fidelity. The extent of site fidelity should be reduced by fluctuating or decreasing territory values.

In determining the value of a territory, it is important to consider how consistent female territorial preferences are during mating season. When males no longer have the ability to reproduce, they are expected to abandon their territories.


How Do I Describe the Behavior of the Female Valley Carpenter Bee?

Virgin females will make exploratory flights foraging and may be attracted by visual and olfactory cues.

The female mate-searching behaviour could involve her waiting at the flower where she finds the markings of the male or flying towards a marked area from afar.


How Do I Describe Nesting In Female Valley Carpenter Bees?

Even when the bees are in the presence of the other sex, the reproductive phase is dormant.

Second, the nesting cycle is characterized by unmated females. Mating also occurs after territorial flight by males, but before nest establishment.

Carpenter bees are named for the fact that they excavate their nests in a variety of woods. The common name of the species refers to California’s Central Valley, where the bees are often found.

X. Sonorina nests in telephone poles and fence posts. And structural timbers. Bees tunnel through the wood using their mandibles. They do not ingest wood during the process and avoid painted or stained wooden surfaces.

The tunnels are 6-10 in long (15-25 cm), and they consist of a series of partitioned hive cells. The majority of X nests are X. Sonorina contains a female and her brood.

Because Xylocopa is not aggressive species, the primary way to defend is by building well-constructed partitions in the cells, blocking the entrance of the nest with various methods, covering the partitions with liquids or sacrificing the entire brood from a nest which has been compromised by parasites.


How Do I Describe Pollination By the Female Valley Carpenter Bee?

These bees are reliant on flowers for food and water. They visit certain plants in a particular pattern throughout the day and pollen is used by the females for their brood.

Female bees collect pollen by touching the anthers of most flowers with their hind legs. However, in the case of closed anthers such as those of Solanaceae, buzz pollination is used, whereby the pollen comes out of the anther after the vibration of the indirect flight muscle of the bee.

The foraging behaviour of X. Sonorina makes a series of quick movements between flowers. In a 1996 study using Asystasia gangetica (Chinese violet), X. Sonorina visits 16 flowers in a minute, spending an average of 1.5 seconds at each one. It usually flies towards the flower and lands on its petals before moving down to the corolla.

A second study revealed that X. Sonorina is a primary and a secondary nectar “robber”. Since it “took the nectar through perforations, and did not touch stigmas while doing so,”

When the carpenter bee visits flowers so deep that it can’t reach the nectar using its tonques, it will make perforations near the base of the tubular ovary of the flower and then pollinate the flower.


Read also: Click Beetle In House: Identification and Control


How Do I Describe Thermoregulation By the Valley Carpenter Bee?

The valley carpenter bee is able to adapt to a wide range of environments by changing its foraging habits and flying at different altitudes based on the temperature.

The bees maintain a thoracic temp of between 33.0 and 46.5 degrees Celsius while travelling through an environment with temperatures ranging from 12.0 to 40.0%.

The heat is transferred to the head and abdomen during thoracic and pre-flight heating. The increase in temperature of the head can be attributed to passive conduction while that of the abdomen can be attributed to the physiological heat transfer within the body.

Xylocopa shares the same circulatory anatomy as honeybees and bumblebees. They have a similar aortic coil to bumblebees that acts as a cooling coil, allowing heat to be transferred from the head and abdomen to the blood.

Valley carpenter bees are characterized by large heads that provide a greater surface area to cool convectively.



This bee may have been nesting around or in your home before. Valley Carpenters nest in wood, causing homeowners to fear hordes of bees drilling through heavy timber.

Do not think they will break into every flower. The majority of flowers are easily accessible and do not require robbery by apiary criminals.

The Valley Carpenter Bee, in fact, is an essential native pollinator for passionflowers. They can collect more pollen than honey bees because of their size.

They have been found to be more effective pollinators than honey bees in agricultural settings. Research has shown that they can be used as supplemental pollinators to support many different agricultural products.

Thanks for reading!

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