Carpenter bees are large, black and yellow insects that are frequently seen in spring, hovering around the eaves of houses or under decks and porch rails.
These bees are often mistaken for bumblebees but can be distinguished by their black, shiny tail section. Carpenter bees have a unique habit of excavating wood to create their nests, which is why they are named after carpenters.
The Carpenter Bee life cycle begins in April or May when female bees search for suitable nesting sites. They often choose softwoods, like pine or cedar, and create a tunnel-like nest by chewing through the wood.
Inside the nest, the female carpenter bee will lay its eggs and provide each egg chamber with a mixture of pollen and nectar, which serves as food for the developing larvae.
A fascinating aspect of the carpenter bee’s life cycle is its role as an important pollinator for various plants.
This native pollinator is especially effective at “buzz pollination,” using its thoracic muscles to vibrate and dislodge pollen from flowers. This process benefits garden plants, such as eggplant and tomato, as well as wildflowers.
Carpenter Bee Basics
Identification and Appearance
Carpenter bees are often mistaken for bumble bees due to their similar appearance. However, there are some key differences that can help with identification:
- Carpenter bees have a shiny black abdomen, whereas bumble bees have a hairy, often yellowish abdomen1.
- Male carpenter bees may display a yellow or white face, while females have an all-black face2.
Types of Carpenter Bees
There are numerous species of carpenter bees, varying in size and color. Some common types include:
- Xylocopa virginica, which is large and has a dark bluish-green tint3.
- Xylocopa micans, a smaller species with metallic-blue coloring4.
Regardless of their appearance, all carpenter bees share certain characteristics:
- Solitary by nature, each female creates her own nest5.
- Both male and female carpenter bees can be found feeding on nectar from various flowers6.
Carpenter Bee Life Cycle
Eggs and Larvae
Carpenter bees, like other bees, have a life cycle that consists of eggs, larvae, pupae, and adults.
The female carpenter bee creates individual brood cells for her offspring, where she lays her eggs. These cells are provisioned with pollen, serving as a food source for the developing larvae.
Pupae and Adults
After the larval stage, the bee enters the pupal stage, during which it undergoes metamorphosis to become an adult bee.
In about seven weeks, adult carpenter bees emerge from their brood cells and begin their lives as pollinators.
- Males: White markings on the head.
- Females: Lacks white markings on the head.
Mating and Reproduction
Carpenter bees are solitary bees, meaning each female is responsible for creating her own nest and laying her eggs. Mating typically happens in the spring, and a single generation is produced per year.
Seasonal Changes
The seasonal activities of carpenter bees include:
- Spring (April/May): Mating, nest construction, and egg-laying.
- Winter: Adults hibernate in their nests.
Comparison Table: Carpenter Bees vs. Bumblebees
| Feature | Carpenter Bees | Bumblebees |
|---|---|---|
| Abdomen | Shiny black, mostly hairless | Hairy, yellow or black |
| Pollination | Important pollinators | Important pollinators |
| Social Structure | Solitary | Social, live together in a nest |
| Hibernate | Adults hibernate in their nests | Only queen survives for next year |
Nesting and Gallery Construction
Nest Sites
Carpenter bees choose their nest sites strategically, generally on wood surfaces.
They favor eaves, siding, and fence posts for their homes—particularly when they can access cracks, sills, fascia, and nail holes. These spots provide safety and protection while they create their galleries.
Wood Selection and Damage
Carpenter bees have certain preferences when it comes to wood selection. They may excavate both soft and hard woods but tend to avoid painted wood.
Damage to the wood increases when carpenter bees repeatedly use the same nest sites or create new tunnels close to existing ones. Common signs of wood damage include:
- Holes on wood surfaces
- Sawdust beneath the nesting area
- Yellow-brown stains from fecal matter
Tunneling and Nest Expansion
Carpenter bees create their nests by tunneling into the wood grain. They start by drilling a hole on the wood surface—which can be as deep as an inch—and then change direction, creating a long tunnel.
These tunnels, also known as galleries, serve as brood chambers. Female carpenter bees lay eggs and store food within these chambers.
They may expand these galleries over time, which can lead to structural damage in wooden structures.
| Carpenter Bees | Other Wood-Boring Insects | |
|---|---|---|
| Preferred Wood | Soft and hard woods | Specific wood types |
| Wood Damage | Holes, sawdust, and stains | Varies |
| Nesting | Tunnels and galleries | Varies |
Overall, understanding the nesting and gallery construction habits of carpenter bees is essential for detecting their presence and mitigating potential damage to wooden structures.
By knowing their preferred nest sites, wood selection, and tunneling patterns, homeowners can better identify and address any carpenter bee-related issues.
Myths and Misconceptions About Carpenter Bees
Myth 1: Carpenter Bees Lay Eggs in Wood
Truth: While carpenter bees do create tunnels in wood, they don’t actually lay their eggs directly into the wood.
Instead, they construct individual brood cells within the tunnels, where they lay eggs and provide a food supply of pollen and nectar for the developing larvae.
Myth 2: Carpenter Bees are Aggressive and Frequently Sting
Truth: Male carpenter bees are often perceived as aggressive due to their hovering behavior, especially near their nests.
However, males do not have stingers and are harmless. Females do possess stingers but are docile and rarely sting unless provoked or handled.
Myth 3: Carpenter Bees Serve No Purpose and Only Cause Damage
Truth: While carpenter bees are known for tunneling into wood, potentially causing structural damage, they play a crucial role in the ecosystem as pollinators.
Their method of “buzz pollination” is particularly effective for certain plants, contributing to biodiversity and agricultural productivity.
Myth 4: All Carpenter Bees are Solitary
Truth: While carpenter bees are generally solitary, with each female constructing her own nest, there are instances of semi-social behavior.
Some species exhibit cooperative breeding, where multiple females share a nest and divide responsibilities.
Myth 5: Carpenter Bees Hibernate Throughout Winter
Truth: It’s a common misconception that all carpenter bees hibernate during winter. In reality, adult carpenter bees stay active within their nests, but their outdoor activities are limited due to colder temperatures.
Myth 6: Carpenter Bees Only Nest in Decayed or Damaged Wood
Truth: Carpenter bees have a preference for untreated, unpainted wood, but they don’t exclusively choose decayed or damaged wood. They can tunnel into healthy wood structures, which is why preventive measures are essential for homeowners.
Myth 7: Carpenter Bees Eat Wood
Truth: Carpenter bees do not eat wood. They excavate wood to create nesting galleries but consume nectar and pollen as their primary food sources.
Conclusion
In conclusion, the life cycle of carpenter bees is a fascinating journey from egg to adult, marked by unique nesting habits and vital pollination roles.
While they are often mistaken for bumblebees, their distinctive characteristics and behavior set them apart. Despite their potential for causing structural damage, their ecological benefits as proficient pollinators are undeniable.
Dispelling myths and understanding their life cycle and behavior are key to appreciating and coexisting with these remarkable insects.
Footnotes
Reader Emails
Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about carpenter bees. Scroll down to have a look at some of them.
Letter 1 – Eastern Carpenter Bee
Amazing little critters- Bumble Bee
Location: Savannah GA, USA
February 28, 2011 5:01 pm
Hello!
Its spring, my favorite season. The trees in my front yard are blossoming and ironically they smell like dead fish!! But these bumble bees don’t seem to mind it, in fact, I think they love it! Theire are loads of them. Thought you might like to take a look at the pictures. Any idea what type of bee this actually is?
Thanks!
Signature: Daryll
Hi Daryll,
We hope you are not disappointed to learn that this is actually an Eastern Carpenter Bee, Xylocopa virginica.
Letter 2 – Eastern Carpenter Bee
Stumped by a backyard find!
Location: Wake Forest, NC
February 3, 2012 5:34 pm
My dog found this insect in our backyard yesterday 2/2/12. I’ve never seen anything like it. I’m hoping you can help tell me what it is!
Thank you!
Signature: Megan
Hi Megan,
This sure appears to be an Eastern Carpenter Bee, Xylocopa virginica. You can view higher resolution images on BugGuide for comparison.
Letter 3 – Eastern Carpenter Bee
Subject: Xylocopa virginica – Eastern Carpenter Bee (female?)
Location: Naperville, IL
September 1, 2012 9:40 pm
Hi Daniel~
I have dozens of these large bees visiting the butterfly bushes at my house. I have tried to get a good, clear photo of one for several weeks, but they’ve always got their faces in the flowers, and they don’t linger in any one location for very long, so my shots were always blurry, despite bright, sunny mornings.
By bumping up the ISO, I was able to minimize motion blur yet still get good enough depth of field for the photo. And I finally confirmed that these are not bumble bees, but solitary carpenter bees.
I read that males have whitish faces, but since I see only the back-faced variety, I am wondering if I am looking at it in the wrong way. I hope you have a lovely Labor Day weekend.
Signature: -Dori Eldridge
Hi Dori,
Your efforts paid off. We agree that this is an Eastern Carpenter Bee. Since your photo does not show the individual head on, we are relying on your observations that the face is black, though it does appear to be black in the photo as well. BugGuide provides some nice information on the Eastern Carpenter Bee, including:
“Nests (galleries) are built in dry, standing wood. Conifers are preferred. Eggs are laid on masses of pollen and nectar, several (6-8) to a gallery. One generation per year in most of range. Adults emerge in late summer, overwinter, mate and nest in spring. Perhaps two generations per year in Florida.”
Thank you, Daniel! I thought I sent a second, full-face photo of the carpenter bee, but I mustn’t have. My bushes are teeming with them now – late summer emergence. Luckily, they don’t appear to be drilling into my wooden siding. We had an exciting day here yesterday.
A wooly bear caterpillar we found in our garage several weeks ago and kept as a “pet” was a bit overdue in emerging from its cocoon. I had been checking it daily, and yesterday when I lifted the mesh screen door of its box, I immediately saw a tiny exit hole in the cocoon, but no Isabella Tiger Moth. Instead, there was a guilty, but pretty nonetheless, red-eyed tachinid fly.
They seem well represented on whatsthatbug.com, so I won’t bother you with photos, but I did identify it as Leschenaultia bicolor, and in all my years rearing Monarchs, I have never heretofore come across one of these parasitoid flies. It was quite a surprise.
All the best to you,
-Dori Eldridge
