What's That Bug? does not endorse extermination

Subject: What is this Western Bluebird eating?
Location: 40º18’14,10″N, 121º52’22.43″W
December 29, 2014 1:16 pm
Dear Bugpersons,
I photographed a Western Bluebird as it foraged with conspecifics in a huge oak woodland in Northern California at 783 meters elevation. It carried a larvalike thing onto the road surface and proceeded to whack it to death! The attached photo shows the unfortunate prey object pre-whacking. What bug is that?
Many thanks.
Signature: Sylvia

Western Bluebird eats Cutworm

Western Bluebird eats Cutworm

Hi Sylvia,
Thanks for submitting your excellent Food Chain image.  Our good friend lepidopterist always says that insects, including the caterpillars of butterflies and moths, exist to feed birds.  This caterpillar appears to be a Cutworm in the subfamily which you can find represented on BugGuide, possibly a Winter Cutworm.

Subject: Western Bluebird
December 30, 2014 12:34 am
Thank you for your speedy reply! Winter Cutworm looks correct. Here’s an edited photo that shows a little more detail of the caterpillar. Rather disheartening to learn that this introduced species is so widespread, but I doubt that the Bluebirds mind.
Signature: Sylvia

Western Bluebird eats Cutworm

Western Bluebird eats Cutworm

Thanks for the update Sylvia.  The nice thing about some introduced species is that they do provide food for native species.

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What's That Bug? does not endorse extermination
Location: Northern California

2 Responses to Western Bluebird eats Cutworm

  1. Erl Svendsen says:

    I would like permission to use the image on this page for a new cutworm identification and management field guide (author is Dr. Kevin Floate of Agriculture and Agri-Food Canada).
    The field guide will be distributed free of charge and will be posted to the Government of Canada’s website and on partner websites. The intent of this publication is to educate producers about the different cutworm species and to limit pesticide application to only when necessary and in the correct manner (e.g. early evening for climbing species when pest is out). The main body of field guide is about how to identify the various crop pest cutworm species. The introductory sections covers history of outbreaks, general biology and control options. This latter section talks about integrated pest management strategies including being aware of natural enemies like predator insects, parasitoids, disease and vertibrate predators like birds. The image would perfectly illustrate how birds are an important of the ecosystem.

    • bugman says:

      Hi Erl,
      Though we are not in contact with Sylvia, WTB? does reserve the right to publish images and letters to our site and other publications. We will search for a higher resolution image in our files and forward the image you requested. Please credit Sylvia as the photographer and image courtesy of What’s That Bug?

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