Do you know what this caterpillar is?
Location: San Diego, CA
May 27, 2011 12:31 pm
We found this caterpillar in San Diego CA at Mission Trails Regional Park on a willow tree. We can not figure out what it is. Can you help. Thanks.
Signature: D in SD

What's That Nymphalid Caterpillar???

Dear D in SD,
The basic coloration and morphology of your caterpillar and its presence on Willow immediately suggested a Mourning Cloak, known as a Camberwell Beauty across the pond, however, no photos on BugGuide look like this.  Mourning Cloak Caterpillars are black spiny creatures (DO NOT TOUCH) and they have 8 rows of orange red dots along the back.  Your caterpillar appears to have 9 double rows of orange spines and its variegated pattern is beautiful.  We really wish your lateral view was not so blurry.  We suspect your caterpillar, whatever it might be, may irritate human skin if in contact with the spines.  We did additional research and the Green Comma,
Polygonia faunus, also feeds on “willows and birches and others” according to Jeffrey Glassberg’s book Butterflies through Binoculars The West.  The photos we found online look even more drastically different than the Mourning Cloak Caterpillar photos posted to BugGuide.  Could it be Chlosyne harrisii Harris’s Checkerspot, which we found on the Moth Photographers Group by scrolling down the page.  What does Chlosyne harrisii eat?  NOPE according to BugGuide, it ranges elsewhere.  Here is the Butterflies and Moths of North America website page on the Green Comma.

Brush Footed Butterfly Caterpillar on Willow

Alas, our search has turned up nothing conclusive.  We strongly believe that the key to a correct identification here is the presence on Willow.
P.S.  NEW THOUGHT:  Might it be a moth caterpillar like a Buck Moth?

Correction courtesy of Keith Wolfe
“D” and Daniel, this is a Hemileuca (Saturniidae) larva.  These nymphalid look-alikes confused me, too, when I first started studying young butterflies.
Best wishes,

Hi Keith,
Funny, Buck Moths did cross my mind when I was researching this caterpillar.

Hi there.  Thanks for looking into this for me.  After looking Butterflies and Moths of N.A. I do think it is a Nevada Buckmoth.
I really appreciate the time you took to check it out.
D in SD

Bill Oehlke supplies a response
It is definitely Hemileuca nevadensis for first one
and for second one as well.
Bill Oehlke

Location: California

10 Responses to Buck Moth Caterpillar

  1. ChristineR says:

    Hi! I have to say that I have found the same caterpillars in the same location, and I’ve been doing some extensive research and while I agree that it is a Hemileuca I do not think it is a Nevada Buck Moth as from all the pictures I can find those they have a different coloration. Their skin appears distinctly speckled in appearance with some prominent striping on the sides. These San Diego Hemileuca have a much more yellow color as well as a more mottled appearance to their skin and not the distinct speckling seen in H. nevadensis, H. electra, or H. eglanterina that are said to be the only Hemileuca found in San Diego county. It is my understanding that Hemileuca are prone to pockets of specific population variance. I think we may have one of those small specific area population variances in this case, and that this sp. may be a local sub sp. of Hemileuca (Saturniidae). But we will see. I have brought 5 of them home and am feeding them fresh salix every day. I have posted photos of them on Bug Guide and as they mature I will continue to update those. Kind Regards, Christine – San Diego

    • bugman says:

      Hi Christine,
      Thanks for this update. We also hope you will supply What’s That Bug? with images of the adult Buck Moths when they emerge. We will also try to contact Bill Oehlke to see if he has anything to share or add to this.

    • bugman says:

      Bill Oehlke supplies a response
      It is definitely Hemileuca nevadensis for first one
      and for second one as well.
      Bill Oehlke

  2. ChristineR says:

    Hi Daniel, I would be happy to add my photos. Thank you for looking at them Bill and posting. Kind Regards,

  3. Jenniffer Lindsley says:

    Hi, We have found several of these caterpillars in our yard, either hanging out in a Black Walnut, Oak, or Sycamore tree. Ours seem to be lighter, with a yellow body and rows of those scary looking spines. Just FYI, as it is 2013 now and I live in East Sand Diego county (Alpine). Thanks for the info, especially about the color variation. That helped us in identifying this guy in the jar. Also, are they supposed to be large? This one is about 3 inches long. Thanks again, Jenniffer

  4. Marilyn Gagnon says:

    The only moth that flies in the daylight is the Buckmoth, the Hemilieluca. We filmed them many years ago in Sharon, MA. for Many World’s of Nature, film company owner, Mildred Morse Allen photographer for WGBH Channel @ Boston, MA. Found them mating, laying eggs, hatching, eating the bushes, pupating. I have forgotten the source, possibly one of the Willows and flying in daylight. I would like to know the two food sources that were in our back yard area, high lines, we had both. Wonderful teaching film. Would like the name of the food source they require.

    • bugman says:

      There are numerous diurnal moths, including Clearwings in the family Sesiidae, like this Virginia Creeper Clearwing pictured on BugGuide and Wasp Moths in the tribe Arctini including the Polka Dot Wasp Moth also pictured on BugGuide.
      According to BugGuide, the larval food for Hemileuca maia, the Buck Moth, is: “Larvae feed on Oaks, Quercus, especially Scrub Oak, Quercus ilicifolia.”

  5. Yes there are the scrub oak in our area and definitely remember the Oak leaves on these Srcub Oaks. Did think there was another food source in our area, but the Buckmoths were eating the Oak leaves of the Scrub Oaks that were so close on our land and doing all their things we photographed. Amazing story of these Buckmoth flying around in the daytime. I do not know the other in our MA area that would fly around in Daytime that are mentioned above. We only had the one. Wish I had a copy of her film, it is only fifteen minutes long and has all the important info.

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