Everything About the Blue Mud Wasp: Facts and Information

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In this article, we will share a collection of blue mud wasp facts, such as where they come from, what they eat, and how they are able to kill spiders much larger than themselves.

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Are you scared of spiders? Particularly the poisonous black widow spiders?

If yes, then the blue mud wasps are your savior. They are one of the 30-plus species of mud dauber wasps and are known to hunt and eat black widow spiders regularly.

But since they hunt such dangerous spiders, they, too, are dangerous to humans, right? Wrong!

Let us know about them in detail.

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Blue Mud Wasp Facts
Blue Mud Wasp

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What Are Blue Mud Wasp?

Blue Mud wasps are the sworn enemies of black widow spiders.

These wasps are experts in hunting down and consuming black widow spiders, which are extremely dangerous and poisonous to humans.

Blue mud wasps are also known as Chalybion Californicum and Blue mud dauber.

They are solitary in nature and are not found in wasp colonies. The female wasps individually build and supply food to their nests.

They belong to the Sphecidae family.

These magnificent insects are found throughout northern Mexico to Southern Canada. You can also spot them in other regions of Bermuda and Hawaii.

But how can you identify these species of mud dauber wasps?

Let us find out in the next section.

What Do Blue Mud Wasps Look Like?

As the name suggests, the blue mud wasps can be identified by their blue and black colored bodies.

They have a tiny thread-like waist(like a narrow cylindrical tube) and show an average growth of 0.47- 0.7 inches in length.

Adult wasps can fly and have blueish wings. The larvae are legless with creamy white bodies and are mostly around an inch long.

If you look closely, you will notice a stinger that the adults use to paralyze and hunt down spiders.

As they are good pollinators, you can find them flying around common wildflowers, searching for nectar.

Blue Mud Wasp

What Does A Blue Mud Wasp Eat?

Blue mud wasps are carnivorous when in their larval stage, but after they reach adulthood, they mostly rely on nectar to fulfill their diets.

The adults are experts in hunting down spiders by stinging and paralyzing them, which then become food to the larvae (we will explain this in-depth later).

Adult wasps mostly rely on nectar to fulfill their food needs.

You can find them around common wildflowers like Zizia Aurea, Daucus Carota, and Berberis Vulgaris.

Where Do Blue Mud Wasps Live?

As mentioned above, blue mud wasps are found throughout northern Mexico to Southern Canada.

In the US, it is most common in the Michigan area, especially near the Great Lakes region.

Unlike the organ-pipe mud daubers, these wasps do not build their own nest; They often occupy the pre-existing nest of the black and yellow mud daubers.

On spotting black and yellow mud dauber nests, they remove the existing larvae and other unwanted species from the mud cells.

Once done, they replace the cells with their own eggs.

These nests are often found near shaded areas like the underside of bridges, abandoned machinery, and wooden piles.

Life Cycle of A Blue Mud Wasp

The life cycle of a blue mud wasp shares many similarities with other species of mud daubers, but there are a few unique aspects that we will discuss in this section.

After mating, the female blue mud wasps search for existing black and yellow mud dauber wasp nests.

Interestingly, the female blue mud wasp uses water to soften the existing nest. They empty the mud cells by eliminating the existing larvae and spiders.

Each mud chamber is filled with one egg and plenty of spiders to allow the larvae to grow into active adults.

Once the process is done, the sections are covered and closed with mud. The female departs soon after that.

Blue Mud Wasp

The larva consumes all the existing spiders in the chamber before emerging.

Once the larva reaches around 0.75 inches, it starts pupating.

These larvae overwinter in the mud chambers and usually emerge during late spring or early summer.

You will be fascinated to know that the adult eats its way out of the mud chamber.

As adults, these wasps fly around wildflowers to drink nectar to fulfill their diets.

You can find them near spider-infested areas, hunting to feed the young ones.

How Long Do Blue Mud Wasps Live?

As adults, the various species of dirt dauber wasps do not live long. After emerging from the mud cell, an average mud dauber adult can live for 3 to 6 weeks.

Also, predators like birds hunt them down, cutting down their lifespan.

These insects live longer as larvae. In winter, these larvae enter diapause till spring.

Do They Bite?

Blue mud wasps have a stinger. They use it to paralyze prey like spiders. Yes, they can sting humans, but they usually do not attack.

However, you must be careful around them and not try to scare or manhandle these insects. The stings can be a little painful.

Are They Poisonous/Venomous?

Blue mud wasps are not poisonous to humans. However, as we mentioned above, adult mud daubers can sting.

Try not to scare the insect by touching them; they might use the stinger on you.

The stings can be temporarily painful and cause mild swelling. You can apply ice to lower the swelling and pain.

Are They Harmful or Beneficial to Humans?

Yes, blue mud wasps can sting humans, but they are rarely aggressive. They will sting if you try to threaten them. If you leave them be, there is no need to worry.

These wasps are beneficial to humans as they eliminate the poisonous black widow spiders.

Also, since they hugely rely on nectar to fulfill their diets, they are decent pollinators.

If you have an annoying population of spiders in your garden, these wasps can be the ideal tool to help you get rid of them.

Also, as they fall from one flower to the other, they will carry the pollen in their body. Thus, promoting cross-pollination.

What Are Blue Mud Wasps Attracted To?

Blue mud wasps are attracted to areas with abundant spiders, especially black widows.

Plus, the females look for shady spots to find mud nests of other dirt daubers to lay eggs.

As mentioned above, the adults are particularly attracted to wildflowers like Zizia Aurea, Daucus Carota, and Berberis Vulgaris.

Why & How Do Blue Mud Wasps Hunt Black Widows?

From the beginning, we are mentioning that blue mud wasps are excellent at hunting black widow spiders.

Have you wondered how they hunt such poisonous insects?

Let us find out.

Firstly, the blue mud wasps hunt these spiders to feed their young ones. Black widows are excellent sources of protein that help the larvae to grow.

They usually grab these poisonous spiders from the web and immobilize them using their stinger.

Once the spider is paralyzed, they carefully carry it to the nests of mud and put it in a mud chamber for the larvae to eat.

At times, these wasps lure the black widows to come out in the open to hunt them conveniently.

How To Get Rid of Blue Mud Wasps?

Blue and wasps usually do not pose any threat to humans. They are beneficial as they eliminate spiders and promote pollination.

However, having mud nests around the house can be a little too much to take.

You can carefully scrape off the nest of blue mud wasps to get rid of them.

Do not worry; the mother does not guard and defend the nest. In fact, they leave the mud nests after sealing the cells.

You can also use organic wasp and hornet aerosol sprays to treat the nest.

Look out for mud dauber nests in shady spots.

Interesting Facts About Blue Mud Wasps

The sections above pretty much carry all the information about blue mud wasps.

But there are a few more fascinating facts about these insects. Let us take a look.

  • Blue mud dauber wasp larvae can consume many spiders. A mud dauber nest cell has around 25 paralyzed spiders.
  • Potter wasps can be mistaken for mud daubers. You can differentiate between the two by observing the nest. Potter wasp nests are in the shape of a pot, and mud daubers have cylindrical nests.
  • Significant populations of blue mud wasps have started blooming in regions of Hawaii and Bermuda.
  • Blue mud wasps also lay a single egg in each mud cell of the nest.

Frequently Asked Questions

Are blue mud wasps harmful?

Blue mud wasps are not typically harmful to humans. They are solitary wasps that primarily feed on nectar and pollen from flowers.
The female blue mud wasp will use her stinger to paralyze spiders, which she then lays her eggs on for her offspring to feed on when they hatch.
While the sting of a blue mud wasp can be painful, they are not known to be aggressive and will only sting if they feel threatened or provoked.
Overall, blue mud wasps are beneficial insects that help control spider populations and are not a significant danger to humans.

What do blue wasps do?

Blue mud wasps are a type of solitary wasp that are known for their unique nesting behavior.
They use mud to build their nests, which are typically located in sheltered areas such as under eaves or in crevices.
Once the nest is made, the female wasp will lay her eggs inside and then hunt for spiders to feed them.
These mama wasps can find and capture black widow spiders, which they then paralyze and bring back to the nest.
Despite their fearsome reputation, blue mud wasps are not typically aggressive towards humans and are considered to be beneficial insects due to their role in controlling spider populations.

What happens when a blue mud wasp stings you?

Wasp stings, in general, can be painful. They can cause swelling and redness.
The venom of the blue mud wasp contains toxins that can cause an allergic reaction in some people. Allergic reactions can be dangerous.
Some people might have extreme symptoms like difficulty breathing, hives, and even anaphylaxis in severe cases.
If you suffer from an allergy to insect bites and stings, you should seek immediate medical attention.
Treatment may include anti-inflammatory medication, antihistamines, and in some cases, epinephrine.

What kills blue mud wasps?

Birds and spiders are the most important predators of blue mud wasps. Larger insects can also attack them.
Humans, of course, are a major reason behind the diminishing populations of these beautiful creatures.
Pesticide use, habitat destruction, and climate change are three major reasons that kill wasps like blud mud daubers.
Pesticides not only kill the blue mud wasps but also affect their food sources, leading to a decline in their population.
Deforestation and urbanization limit the availability of suitable nesting sites and food.
Climate change alters the timing of the blue mud wasp’s life cycle, affecting its survival and reproduction.

Wrap Up

Yes, blue mud wasps are a nightmare for spiders, including the poisonous black widows.

These wasps are excellent for removing pests like spiders and promoting pollination. However, they can sting if you threaten them. Do not try to manhandle them, and you will be fine.

If you find it annoying to deal with the mud nests around your house, use the tips mentioned in the article to get rid of them.

Thank you for reading!

Reader Emails

Blue mud daubers are so unique in their appearance and so fearsome in reputation that we have often received queries from our readers about them in the past.

We have collected below some of the questions, our answers, and of course, a selection of beautiful photographs of these wasps.

Please go through it.

Letter 1 – Blue Mud Wasp

 

What is this???
My 4 year old son is a bug addict. We have been catching and taking pictures of every bug he finds so that we can release them after we have the picture. We then find them in one of our many bug books and keep the pictures in a special book for him. Problem is we can’t classify this one. Can you?
~Joanne

Hi Joanne,
This may be a Blue Mud Wasp, Chalybion californicum, but you did not provide us with a location and that would have helped greatly. We will see if Eric Eaton can assist us. Eric provided this information: “You were right the first time:-) It appears to be a male Chalybion californicum, the blue mud dauber. Chlorion are slightly more robust, and a whole lot more shiny in images this well lit.”

Sorry, we are in Ontario Canada.

Letter 2 – Blue Mud Wasp

 

Blue Flying Bug (with pitchure)
Dear Bug man,
I have seen this bug for the first time this year (July/Aug 2006) Can you tell me what it is and if it is a harmful bug. I live in San Diego California, Ramona to be exact. I have also witnessed this bug in Payson Arizona. Thanks
Oddley Curious of San Diego

Dear Oddly Curious,
This is a Blue Mud Wasp, Chalybion californicum. The female provisions her nests with spiders, especially comb footed spiders.

Letter 3 – Mysterious Black Wasp Aggregation: Blue Mud Daubers

 

Please help me identify this bug
Dear Bugman,
I live in south Texas and I have noticed these guys showing up at dusk and leaving in the morning all spring. At first they would land on one of my ferns in a hanging basket. They seemed to like one particular frond. I began to worry that the fern was being damaged, so I moved it away. That night they showed up and moved in on my ivy basket. This time they aren’t on the plant itself, but just the pot. There are so many on the bottom of the pot that it gives me the willies. I wish they would go away, but I’m not going to kill them. Any idea what they are? Thanks for your help.
Teresa Eaton

Hi Theresa,
The behavior you describe and have photographed is something we have encountered with the in the past, but those were striped wasps. BugGuide shows genus of black Tiphids, Tiphia, but we are not certain this is your insect. We will contact your namesake (and perhaps long lost cousin) Eric Eaton to see what he can add.

Update: (06/14/2008)
Daniel:
The image of the large aggregation of wasps depicts male (read STINGLESS) blue mud daubers, Chalybion californicum. The deep metallic color does not always show up well in photos, but this behavior is a real signature of the species. Males are anatomically incapable of stinging, so no worries there. They form these “bachelor parties” to spend the night, but for what reason is anybody’s guess.
Eric Eaton

Letter 4 – Blue Mud Wasp

 

Metallic very large blue/black wasp
Location:  Fairfield, Maine USA
August 9, 2010 12:06 pm
Dear Bugman,
I saw this large iridescent thing wizz by me out in the meadow. I was able to track it down and get a few pictures before it flew away. Is this a Steel Blue Cricket Hunter (Chlorion aerarium) or maybe a Blue mud Wasp? I cannot tell so far. It was quite large, I dare even guess 2 inches long. It is also very active and almost never came to a full ”stop.” it is beautiful, but can/will it sting a person?
Thank you!
James R

Blue Mud Wasp

Hi James,
Nice job of narrowing down the identification of this lovely Thread-Waisted Wasp.  In the past, we frequently mixed up the two, but now we are usually correct.  We believe this is a Blue Mud Wasp,
Chalybion californicum, which if profiled on BugGuide where it is described as:  “A large, active, blue-black wasp with irridescent blue wings. Frequents flowers for nectar and buildings for nest sites. Compare “Steel-Blue Cricket Hunter”, (or “Blue Mud Dauber”), Chlorion aerarium, which preys on crickets. This is about the same size as Chalybion, and is said to have a longer pedicel (narrow waist between thorax and abdomen). The body of Chalybion looks much more hairy, and more steely-blue, based on specimen photos. BugGuide also indicates:  “Females construct mud nests in sheltered areas, often under the eaves of buildings, and provision them with spiders. Sometimes refurbishes the nests of other mud-daubers, such as Sceliphron.” We love that you have abbreviated your photos as “BMW”.

Blue Mud Wasp

Hi Daniel,
Thank you so much for the identification.  I kept going back and forth and finally just had
to ask the experts!
Best wishes,
James

Awesome James.  Be sure to let us know what the experts think.

Letter 5 – Great Black Wasp

 

Subject: Which Wasp?
Location: Long Island, NY
August 26, 2013 3:51 pm
I could not identify this one here or at BugGuide.
A little more help, please?
Signature: Carl

Blue Mud Wasp
Blue Mud Wasp

Hi Carl,
We believe this is a Blue Mud Wasp, Chalybion californicum, but we are not certain.  We will try to get a second opinion.  See BugGuide for photos of the Blue Mud Wasp.  The iridescence of the wings is only visible in your second photo.

Blue Mud Wasp
Blue Mud Wasp

Eric Eaton provides an identification:  Male Great Black Wasp
I’d say a male Great Black Wasp, Sphex pensylvanicus.
Eric

Letter 6 – Blue Mud Wasp

 

Subject: Blue Bug?
Location: Philadelphia, PA
July 1, 2015 11:10 am
Location: just outside of Philadelphia, PA
Date: 6/29/15 Summer
Time: 9:15 am
I have a gift for finding strange bugs. Two different Sphynx Moths, odd grasshoppers, albino spiders and such. This is my first blue bug. 🙂
Signature: Andrea

Blue Mud Wasp
Blue Mud Wasp

Dear Andrea,
This is a Blue Mud Dauber or Blue Mud Wasp,
Chalybion californicum.  According to BugGuide:  “A large, active, blue-black wasp with irridescent blue wings. Frequents flowers for nectar and buildings for nest sites.”

Letter 7 – Blue Mud Wasp

 

Subject: Iridescent Wasp?
Location: Cabot, VT
July 17, 2016 8:03 am
I just found this beautiful wasp-like flying bug, dead in my upstairs window (July). I live in central Vermont, in an old farm house surrounded by cow pastures and woods. We have a small second floor attic space, and I’ve seen both evidence of old wasp nests on the ceiling in there, and live wasps flying out of there. I haven’t seen one like this alive, though. I’ve never seen anything like it, even though I’ve lived in a number of New England farm houses throughout my life. I love your website, and I’m so excited to finally have a bug to send to you!
Signature: Lara

Blue Mud Wasp
Blue Mud Wasp

Dear Lara,
This looks to us like a Blue Mud Wasp,
Chalybion californicum, a species described on BugGuide as:  “A large, active, blue-black wasp with irridescent blue wings. Frequents flowers for nectar and buildings for nest sites.”  BugGuide also states:  “Females construct mud nests in sheltered areas, often under the eaves of buildings, and provision them with spiders. Sometimes refurbishes the nests of other mud-daubers, such as Sceliphron.”

Letter 8 – Common Blue Mud-Dauber Wasps

 

Subject:  Black Flying Insect
Geographic location of the bug:  Upstate New York
Date: 07/20/2021
Time: 06:56 PM EDT
Your letter to the bugman:  Helli, We have these insects around our deck for the first time this year. We have lived here for 30+ years. Are they wasps, hornets or something else? Thank you!
How you want your letter signed:  Susan

Common Blue Mud-Dauber Wasps

Dear Susan,
We believe these are Common Blue Mud-Dauber Wasps,
Chalybion californicum, which are pictured on BugGuide.  According to BugGuide:  “A large, active, blue-black wasp with irridescent blue wings. Frequents flowers for nectar and buildings for nest sites.” and “Females construct mud nests in sheltered areas, often under the eaves of buildings, and provision them with spiders.”  We suspect they are searching for mud near your deck for nest building.

Authors

  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com 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.

    View all posts
  • 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.

    View all posts
Tags: Blue Mud Wasps

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32 Comments. Leave new

  • Hi,
    I live in Surabaya , East Java in Indonesia. I thought you might be interested to know that I have aggregations of a very similar (could it be the same?) species of mud-dauber wasps on my front porch. It started about 2 months ago with 2-3 individuals and now is up to around 20 (difficult to count!) each night. They ‘roost’ on a small brass bell suspended under a wind chime. They appear in numbers an hour or so before dark, buzzing around before settling for the night.
    They are of different sizes ( males and females?) and are unaffected by flashlights or movements in close proximity.
    I will try to work out how to send some photos.

    Reply
  • Hi,
    I live in Surabaya , East Java in Indonesia. I thought you might be interested to know that I have aggregations of a very similar (could it be the same?) species of mud-dauber wasps on my front porch. It started about 2 months ago with 2-3 individuals and now is up to around 20 (difficult to count!) each night. They ‘roost’ on a small brass bell suspended under a wind chime. They appear in numbers an hour or so before dark, buzzing around before settling for the night.
    They are of different sizes ( males and females?) and are unaffected by flashlights or movements in close proximity.
    I will try to work out how to send some photos.

    Reply
  • I just found one indoors, will it sting?

    Reply
    • They are not an aggressive species, but they might sting, so they should not be carelessly handled.

      Reply
  • can they live in New York cause i live there and i found one in my house

    Reply
  • I just found one in my house (I live in south-eastern Ontario, Canada). I was trying to catch it in a cup but it kept flying about in a panicked state, and eventually flew off somewhere and I lost sight of it. The one I saw looked more black than black-blue but it could’ve been the lighting. It was like 1-1.5 inches, HUGE. My son was calling it a “Killer hornet”, lol… glad I now know what it is. I’m glad it’s not an aggressive species because it sure looks a bit evil…. 😛

    Reply
  • Daniel Castaneda
    August 13, 2015 8:12 am

    We just found a nest of these in our tree in central Oklahoma. We have been getting a lot of rain this summer and finding critters we dont usually see this far into summer

    Reply
  • Just found a whole slew of them under the kids plastic slide from the play house.
    Indiana-June 7, 2016

    Reply
  • Just found a whole slew of them under the kids plastic slide from the play house.
    Indiana-June 7, 2016

    Reply
  • I have them on my back deck in akron ,they made a nest in a open space between under the roof I sprayed twice they are not going back in there but still a ton flying around back there and I sprayed a week ago?

    Reply
  • “Provision them with spiders,” eh? Well, we have plenty of spiders for everyone at our house! Thanks for the response!

    Lara

    Reply
  • “Provision them with spiders,” eh? Well, we have plenty of spiders for everyone at our house! Thanks for the response!

    Lara

    Reply
  • i am trying to catch one for my collection, or better yet collect a specimen that is already dead. i have spotted a couple of them flying in and out of a crevice in the concrete on my back patio. any ideas?

    Reply
  • I think they are cricket hunter wasps.There are alot of them here in southern california.There are alot of crickets around right now so the wasps are busy.In the sunlight they are awesome in color.I have been trying to catch one to better id them,but they wont stay stilllong enough to get a cup over them.I was wondering how bad a sting on a human might be?

    Reply
    • Thanks for your input. We cannot say for certain, but we still believe this is a Blue Mud Wasp.

      Reply
    • Hi!
      I was just stung by this type of wasp today. I mistakenly thought it a non-stinging “mud dauber” and tried to humanely remove it from my kitchen. It hurt for a second but did not have the burning sensation or swelling that I’ve experienced from stings by other wasps. Hope that helps.

      Reply
  • Hi I live in the Quad Cities, three hours south of Chicago, and there was a dead wasp looking thing on the ground. It isn’t very large, it is metallic blue, and has a weird looking abdomen. Could this be a young Blue Mud Wasp??

    Reply
  • are these found often in wisconsin found one, but wanted to know if there native

    Reply
  • Have a lot of these flying around here in South Florida…even keep building nests outside door at our condo/apartment.. I’m severely allergic to bees in general.– always nervous when opening door because the nest is there. Also had a couple of them fly inside (uugggg). Any suggestions/ideas of how to rid of their claim outside my door? Thx 🙂

    Reply
    • If possible, put a fan at the entrance of the nest. Departing wasps can leave and returning ones can’t enter. I’ve used this a few times successfully when dealing with stinging insects. Good Luck!

      Reply
  • i have tons of these on my cardone plants that I am growing this year but I dont know how to get rid of them. I dont want to spray any pesticides on these plants cause I plan on eating them.

    Reply
  • But they don’t leave!!!!

    Reply
  • Do they eat wood

    Reply
  • I am at my lakehouse in Talledega, Alabama. Just saw what I think is one. Have an epipen for bee stings. It was quite beautiful, but not as big as being described. Maybe an inch long, altogether? Wish I had taken a picture. I frequently find mud nests around our deck, even on our porch. We have a lot of pines, hardwoods & deadfall trees. Do they sting? And are they known to be in this area?

    Reply

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