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,

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

Location: Fairfield, Maine

26 Responses to Blue Mud Wasp

  1. Ed says:

    I just found one indoors, will it sting?

  2. adam says:

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

  3. Alysha says:

    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…. 😛

  4. Daniel Castaneda says:

    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

  5. Anita says:

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

  6. Michelle says:

    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?

  7. jack says:

    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?

  8. Bradford. says:

    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?

    • bugman says:

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

    • Janet says:

      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.

  9. Grace says:

    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??

  10. Dylin says:

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

  11. Rhonda says:

    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 🙂

    • Rob says:

      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!

  12. martha says:

    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.

  13. Martha says:

    But they don’t leave!!!!

  14. Candace says:

    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?

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