Do Mason Wasps Kill Carpenter Bees? #1 Answer

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Mason wasps often reuse carpenter bee nests, so do mason wasps kill carpenter bees first? Let’s find out!

Mason wasps are indeed a very interesting wasp species, primarily due to their unique nesting habits. 

These wasps do not build their nests from scratch; rather, they make use of existing nest tunnels of other insects and use mud balls to create separate compartments. 

You’ll often come across mason wasps living in nest tunnels dug by carpenter bees, which might make you wonder if they kill these bees. 

Well, the answer is yes; they do kill the occupants of a nest before taking it over. Let’s dive into this article and explore it in detail.

Do Mason Wasps Kill Carpenter Bees? Truth Revealed

What Are Mason Wasps?  

Mason wasps belong to the Eumenine family, a family of wasps known for their diverse variety of nest-building techniques. 

The males of this solitary wasp species are usually about one inch long. The female wasps are a little bigger, ranging from half an inch to 3/4th of an inch.

These types of wasps vary in their appearance, and there are several subspecies in North America. 

For instance, four-toothed mason wasps have black bodies with a white stripe over the abdomen, while red and black mason wasps have reddish markings. 

However, black and white wasps are the most common species of mason wasps. Even the red and black mason wasps often have white spots on their heads.

What Do They Eat?

Like most wasps, adult mason wasps primarily feed on nectar from flowers. This also makes them accidental pollinators. 

Flowers blooming during summer and fall are particularly attractive to them. Occasionally, this wasp species might prey on other insects too.

Do Mason Wasps Kill Carpenter Bees? Truth Revealed

What Do Their Larvae Eat?

Mason wasp larvae are insectivores and feed on insects until they’re ready to pupate.

After laying eggs, adult females also provision the nest cells with caterpillars and other insects. 

They paralyze the prey with their venom and leave them for the larvae to eat.

Once a mason wasp has accumulated enough insects for one larva, it seals the egg cell and moves on to gather food for the next egg.

Where Do They Nest?

As mentioned earlier, the nesting technique of mason wasps makes them particularly interesting. 

Unlike social wasps, each female mason wasp makes her own nest. Suitable nesting sites include nest tunnels bored by other insects like female carpenter bees, boring beetles, etc. 

Once they find an abandoned nest or take over an active one by killing the occupants, they lay their eggs in it. Mason wasps use mud to build walls inside the nest tunnel, partitioning chambers for each egg.

Do Mason Wasps Kill Carpenter Bees? Truth Revealed

Do They Kill Carpenter Bees?

As mentioned earlier, carpenter bee nests are among the preferred nesting sites for mason wasps. 

In case a nest still has carpenter bees living in it, the wasp may kill and eat the female bee and its offspring or eggs. 

Hence, while mason wasps do not specifically prey on carpenter bees, they kill these bees to take over their nests.

Are They Dangerous or Aggressive?

Although mason wasps (especially the females) look very similar to the bald-faced hornet, they aren’t as aggressive. 

However, they would still sting you if you try to mishandle them or disturb them in other ways. 

The females can deliver quite a painful sting – almost as painful as the bald-faced hornet. Unlike most wasp species, male mason wasps are capable of stinging too. 

However, as they don’t have stingers and use the tip of their abdomen to sting, they can’t inject any venom.

Do Mason Wasps Kill Carpenter Bees? Truth Revealed

Are They Beneficial?

Yes, these black wasps are among the various beneficial wasps that you should keep in your garden. 

Firstly, they’ll keep the pest population under control by hunting garden pests for their larvae. 

Secondly, they’re excellent native pollinators and can help your garden thrive. As long as you don’t disturb them or make them feel threatened, it should be okay to let them stay.

Frequently Asked Questions

What is the natural enemy of the carpenter bee?

As pointed out previously, mason wasps are one of the natural enemies of carpenter bees and often kill them when taking over their nests. 
Besides mason wasps, other notable natural enemies include woodpeckers, bee flies, shrikes, ratels, etc. 
Bee flies may not kill carpenter bees directly, but they destroy the eggs by draining all the egg fluid.

What wasp uses carpenter bee holes?

Mason wasps make use of carpenter bee holes to turn them into their own nests. Apart from taking over abandoned nest tunnels and holes, they often occupy active nests too. 
To do this, the mason wasps first kill the current occupants, from the eggs to the larvae and even the adults.

Are carpenter bees afraid of wasps?

Yes, carpenter bees perceive wasps as a threat and are afraid of them. 
This is because certain wasp species, like the mason wasp, often kill carpenter bees and their eggs or larvae and eat them up. 
This is why these bees avoid nesting in areas with wasp colonies.

What is the best way to get rid of carpenter bees?

You may use carpenter bees’ fear of wasps to get rid of them. Simply build a fake wasp nest using a brown paper bag and hang it near wood structures that carpenter bees might bore into. 
Of course, other methods like spraying insecticides and using non-toxic repellants work too.

Wrapping up

Carpenter bees aren’t as destructive to wood structures as carpenter ants – they only bore small tunnels to nest in. You don’t have to worry about them ruining your home unless there are too many carpenter bees boring nests every year. 

The mason wasps aren’t much of a problem either since they mostly reuse holes dug previously by other insects. 

If you want to stop them from nesting on your property, just use steel wool, caulk, or aluminum foil to seal up holes in the wood. 

Hopefully, this article was enjoyable to read and has answered your questions.

Reader Emails

Some of our readers have shared with us their experiences with these beautiful wasps, their nests, and their penchant for finishing off carpenter bees and taking over their nests.

Do go through to see some excellent pics of these wasps

Letter 1 – Mason Wasp


Large Black and white wasp
Can you identify this wasp for me, and tell me a little about it. Wasps are a hobby of mine, but I have never seen this one in any book. They are very common at Brazos Bend State Park in Texas, where I am a volunteer, and are frequently seen going in and out of holes in wood, or walking on open soil or sand.
Thanks very much..
H. Glen Kilgore

Hi H. Glen,
Your photo is blurry, but it sure looks to us like a Mason Wasp, Monobia quadridens. According to BugGuide, the Mason Wasp: “Usually nests in wood borings, but sometimes burrows in dirt banks. Sometimes takes over abandoned nests of carpenter bees or ground bees, also Sceliphron (mud dauber) cells. Nest is provisioned with caterpillars, and cells of nest are separated by mud partitions.”

Letter 2 – Mason Wasp captures Caterpillar


Food Chain Location:  North Middle Tennessee August 14, 2010 1:35 pm Hi Daniel, I thought this was a potter wasp a few weeks ago, but now I don’t know what it is. I noticed a hole bored in the bottom of the deck rail a couple of days ago. (Sawdust below it) I looked into the hole and it was empty. It was approx. one and a half inches deep. Today I saw this struggle going on and ran for the camera.
Mason Wasp with Caterpillar
The worm/grub was almost more the the wasp could carry. I watch and snapped photos untill it finally got into the hole. It left the worm/grub in the hole. I will keep an eye on the hole to see if she closes it of just leaves it open. I never saw these black and white wasp looking things before this year. The adults appear to feed on pollen. Thanks and have a great day. Richard
Mason Wasp with Caterpillar
Hi Richard, We believe we have correctly identified your Mason Wasp as Monobia quadridens on BugGuide which indicates:  “Usually nests in wood borings, but sometimes burrows in dirt banks. Sometimes takes over abandoned nests of carpenter bees or ground bees, also Sceliphron (mud dauber) cells. Nest is provisioned with caterpillars, and cells of nest are separated by mud partitions.”  A very similar looking species is Euodynerus bidens, also profiled on BugGuide.  The two can be distinguished from one another by this method:  “Nearly identical to Monobia quadridens. Large rounded white spots on the propodeum (smaller or absent in Monobia quadridens) and smaller rounded white spots on the temples (present only in Euodynerus bidens) are used to distinguish the two.”  Your photographs are beautiful.
Mason Wasp with Caterpillar Prey

Letter 3 – Mason Wasp


Subject: wasp ? Location: Amherst Nova Scotia Canada May 23, 2014 5:45 pm I took this picture May 22 2014 on our front deck, I have tried to identify this insect but cannot Signature: Charles W Linney
Mason Wasp
Mason Wasp
Hi Charles, This is a Mason Wasp or Potter Wasp in the family Eumeninae.  We are having trouble identifying it to the species level since so many species and genera look so similar, so we will leave that to an expert.  Members of the family, according to BugGuide:  “prey mainly upon moth larvae” and they provision their nests with the caterpillars to provide food for the developing larval wasps.  The nests often resemble small ceramic pots and they are constructed of mud.

Letter 4 – Mason Wasps occupying Mason Bee nests


Subject:  solitary wasp identification Geographic location of the bug:  Topanga Canyon, Calif 90290 Date: 08/07/2018 Time: 08:52 PM EDT Your letter to the bugman:  Three years ago these unaggressive wasps started taking over my unoccupied  mason bee nests.  They come out in April-May and by middle of June most of the nests are plugged up. How you want your letter signed:  John
Mason Wasp
Dear John, The quick and easy answer is that this is a Mason Wasp in the subfamily Eumeninae, and BugGuide states:  “Most species nest in pre-existing cavities (e.g., old borings in wood, hollow stems, crevices in rocks). They are called mason wasps because they use mud (or less commonly sand) as partitions between their brood cells. Some species construct nests in the ground (e.g., all Pterocheilus, Odynerus, Euodynerus annulatus, E. auranus, E. crypticus). Some ground-nesting species build small mud turrets over the nest entrance (Odynerus dilectus, Euodynerus annulatus). ” Ancistrocerus tuberculocephalus which is pictured on BugGuide looks very similar, and of the genus contains hole nesters according to BugGuide.  We found an image on BugGuide of Euodynerus annulatus that is a near perfect match and it was found in the Los Angeles area, however BugGuide states:  “Nests in the ground. Unlike other ground-nesting Euodynerus it constructs a mud turret over the nest entrance.”  BugGuide does picture another member of the genus nesting in holes, and Eric Eaton’s blog pictures yet another member of the genus nesting in Mason Bee blocks.  So, we don’t feel confident providing you with either a species or a genus at this time, but we will continue to research this matter and we will consult with Eric Eaton to get his opinion. In a shameless bit of self promotion, Daniel did a slide lecture on insects at The Topanga Mermaid in May 2017.
Mason Wasp
Eric Eaton confirms Identification It’s a Euodynerus, but I don’t know which one.  You can seldom go by color pattern alone.
author, Kaufman Field Guide to Insects of North America
Mason Wasps
Thanks for making the effort to identify my nesting wasp(s).  It sure looks almost exactly like the photo of the Euodynerus Annalatus in the Bug Guide.  The color patterns on the abdomen are identical, and the antennae also look the same (single joint and wider downward curved pointy end).  For my purposes it’s enough to know what the Mason Wasps do in their short active life…capturing caterpillars is usually a good thing. Sorry I missed the Topanga Mermaid lecture, I read about it after the fact. My next project is to identify and learn how to attract predatory wasps that attack spider mites, especially the two-spotted kind. John


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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Tags: Mason Wasps

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