What's That Bug? does not endorse extermination

Big Blue Flying Insect
August 17, 2009
These bugs are living in a stone wall where I work in Rhinebeck, NY (it is summer right now). They fly out and bring back grasshoppers that seem to be paralyzed when they bring them back to the wall. They disappear with them in the wall and then a few days or weeks later (not sure) they drop the shell of the grasshopper out of the wall-like the entire inside has been eaten out.aaaaaaaa
Teresa B
Rhinebeck, NY

Blue Mud Wasp

Great Black Wasp

Dear Teresa,
This is one of two species of Thread Waist Wasps that we have trouble distinguishing from one another.  We believe it is a Blue Mud Wasp, Chalybion californicum, which according to BugGuide is :  “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.”  The other possibility is that it is Chlorion aerarium, also depicted on BugGuide. which states:  “Habitat  Although generally not closely associated with humans, they are found wherever their hosts (Gryllus crickets) are found, which could include close proximity to homes (though not so much as Sceliphron and Chalybion). Chlorion is usually found in open areas such as meadows, overgrown fields, dunes, beach edges, etc., although they may not necessarily hunt in the same habitat as they nest. They are sometimes associated with the Cicada Killer where the ranges of these two wasps overlap, C. aerarium digging burrows off side of the larger wasps nest (O’Brien, 1989).
Season  Late July and early August (in Michigan)
Remarks  Females mass-provision several serial cells, each containing from 2 to 9 nymphs or adults of Gryllus pennsylvanicus. Prey are transported on the ground, venter-up, with the wasp’s mandibles grasping the antennae of the cricket.
”  It is worth noting that the adults of both species feed on nectar and pollen, and the crickets are used as food for the brood.  We will contact Eric Eaton to see if he can provide the exact identification.

Blue Mud Wasp

Great Black Wasp

Ok, here are all the identifications:
The “blue mud dauber” or “Chlorion” is neither.  These are two nice images of a female “great black wasp,” Sphex pensylvanicus.  They hunt katydids as food for their larval offspring, as the submitter observed.
Keep up the great work!

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13 Responses to Great Black Wasp

  1. Leana Kirkreit says:

    I have a question please. One of these great black wasps comes on to our patio and attracts the attention of our Maine Coon cat, who loves to catch bugs, will it hurt him if he eats it?

  2. Callie Saunders says:

    I live in Ohio. I have seen these and I just want to know if these bugs can hurt me?

  3. Kim Cooper says:

    I would call it blue wasp I found it in NSW Waitara Australia have they imigrated from USA?intrestingKim

    • bugman says:

      We have not found any information about the North American Great Black Wasp being introduced to Australia. Most likely you observed a more local species like this Australian Black Flower Wasp pictured on FlickR or perhaps a Blue Flower Wasp.

  4. Billy L Mcdonald says:

    I have found 6 of these in the last month. In only one room of the house. I am in South Texas. Looks like the Great Black Wasp. Doors stay closed. AC on all the time. Where are they coming from.

  5. Jessica Boster says:

    can these bugs multiply ? do they sting you ?

    • bugman says:

      Like other insects, Great Black Wasps mate and reproduce. Female Great Black Wasps have a stinger, but they are not considered dangerous nor aggressive.

  6. Luis says:

    I have found a nest i cant tell how many of them . Do they sting humand or dogs can they be harmfull . They are great looking insect i would not want to get rid of them .

    • bugman says:

      They are not aggressive. Might sting a dog if it tried to eat one, or a human if the human catches one with hands.

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