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Blue Mud Dauber Wasps Building Nests

9-8-17 blue mud wasp 049A4450

Yesterday’s Mystery Photo showed evidence of a Blue Mud Dauber Wasp (Chalybion californicum) scraping the mud with its mandibles as well as the resulting ball of mud it had formed to use as building material for its nest.  You can get a hint in this photograph of the iridescent blue wings that give this wasp its common name.

Mud dauber is a common name for solitary wasps that make individual nests for their eggs/brood with mud. There are many species of mud daubers, but most are between one and one-and-a-half inches long, black or metallic blue, and typically have a narrowing, or “thread-waist,” between their thorax and abdomen.

Most species of mud daubers, after making a small (1/4” diameter) tube nest out of mud or refurbishing an old nest, leave to forage for spiders. Once a spider has been located, the wasp stings and paralyzes it, but does not kill it (so as to prolong decomposition), carries it back to its nest, and repeats this process over and over until the nest is stuffed with living prey. The wasp then lays an egg in this mass of spiders and seals the nest with mud. The egg hatches and the wasp larva consumes the spiders as it grows. After pupating in the fall, the adult wasp emerges in the spring, mates and the cycle continues.

The reason that the ball of mud that the Blue Mud Dauber had formed was not taken back to the nest site as building material appears to be a small rootlet which anchors the ball to the ground, preventing the wasp from removing it.

4 responses

  1. Alice Pratt

    Fascinating!

    September 8, 2017 at 8:28 am

  2. Shelagh in Vermont

    I see these blue wasps around my little goldfish pond all the time, usually sipping water, but have never found a mud ball like this. Well spotted!

    September 9, 2017 at 4:25 am

  3. Laurie Spry

    So interesting, Mary. Thank you.

    September 9, 2017 at 7:32 am

  4. Bill On The Hill...

    Once again Mary, you never cease to amaze me with these sprinklings of nature’s wonders immediately below our noses!
    Thank you,
    Bill Farr… 🙂

    September 12, 2017 at 8:23 am

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