Grammia Tiger Moth Caterpillar

2008 June 7

Back on March 30, there was a rare sunny, not-quite-freezing day, and we took the opportunity to take a walk down the road. On the shoulder of the road, right next to our yard, we spotted this caterpillar:

Tiger moth caterpillar

It had obviously overwintered as a caterpillar, it certainly hadn’t gotten that big in the approximately 3 above-freezing days that we’d had at that point. It looked it, too – a bit weathered, kind of scruffy, not moving very fast. It’s certainly a caterpillar of some type of tiger moth, in the family Arctiidae. These are pretty large moths that have fuzzy caterpillars, like the well-known Woolly Bear caterpillar. This one isn’t a wooly bear, but I think it is the caterpillar of one of the moths in the tribe Arctiiini. BugGuide is kind of short of caterpillar pictures here, but from Wagner’s book I was originally inclined to think it was either the Great Tiger Moth, Arctia caja, or the St. Lawrence Tiger Moth, Platarctia parthenos. Unfortunately Wagner’s picture of the St. Lawrence Tiger Moth caterpillar doesn’t look quite right either.

Tiger moth caterpillar side view

The head is black, too, instead of brown

Tiger moth caterpillar head

And the setae (hairs) come out of a kind of warty tuft instead of being spread uniformly over the body



So, on balance, I’m leaning towards the St. Lawrence Tiger Moth, but in either case, the caterpillars are pretty similar as far as habits. They overwinter as partially-grown caterpillars, and then eat a bit more in the spring before pupating and emerging as adult moths. They aren’t very fussy about their food, eating grass, legumes, and pretty much any other low-growing plants that are available. Wagner refers to them as the “musk oxen” of caterpillars, because they are big, hairy, and shrug off the cold. They are also rather long-lived, the St. Lawrence Tiger Moth can take two years to get to adulthood, overwintering twice.

Update: I have been advised by Roar on BugGuide that this is most likely in the tiger moth genus Grammia, so it isn’t either the Great Tiger Moth or the St. Lawrence Tiger Moth, because the hairs are too bristly. As it happens, I have recently gotten pictures of the most common Grammia tiger moths around here, so this is probably what it grew up to look like.

24 Responses
  1. June 21, 2008

    overwinters twice? cool!

  2. December 27, 2008

    I just found one of these today out in my yard…he also is all black, although this guy has no brown on him. He is very hairy, and also has curled up into a ball. I found him today December 27, 2008. In Virginia where the weather has been up and down. Freezing just a few days ago, and 60 degrees Farenheit today.

  3. March 9, 2009

    I found one in my yard after watering it. It was living under my sidewalk part of it in a large dark hole. I’m thinking of keeping it in a box or something and I was looking for what it eats. So like this web says i’m going to feed it like grass. 🙂

  4. March 10, 2009

    Cool! If you get it to mature into a moth, could you let us know how it comes out?

  5. Hailey permalink
    March 12, 2009

    My friend found one of these caterpillars. Well at least it looks like it. We are not sure what kind of tiger moth it is, but she is under the impression that it will turn into a butterfly. Just wondering, is the tiger moth ACTUALLY a moth, because in the pictures i found, it looks like a butterfly. Also, what do tiger moth caterpillars eat?!?!?

  6. March 13, 2009

    The “tiger moth” family is pretty large, and some of them do look more like butterflies than moths. This particular one would grow up to look like a moth, though. According to what information I’ve been able to find, the caterpillars eat grass, although I expect that they like green, growing grass better than dry grass.

  7. Marcie permalink
    April 6, 2009

    We found the black and orange “wooly bear” in our garden April 5 2009 after a winter with 5 feet of snow in the garden. We brought him indoors and hope to see him through to moth stage. I home school, so this is a bit of a project for the kids, trying to recreate his natural habitat in a 2.5 gallon tank with screened lid.

  8. Jo MYnott permalink
    June 13, 2009

    13.6.09, 1030am. I saw two tiger moth caterpillars this morning on Gwithian Towans in Cornwall. One was trying to climb up the sandy slopes and falling down when the going was too steep. The air temperature was about 20C, no wind and sun most of the time. Would the sandy towans have been his natural habitat? .

  9. Brooke permalink
    June 14, 2009

    i found on on my white birtch tree

  10. Eliza permalink
    June 15, 2009

    I dont know if the caterpillar I found was a Tiger Moth. It looks like one, but then a saw a picture of one that looked just like it and it said it was poisonous… I’m not going to touch it just in case it kills me and I die (if that makes any sense). So, I guess I’ll go feed it grass and hope for the best! 🙂 This was from the prospective of a curious 13 yr old.

  11. June 16, 2009

    Eliza: A lot of the furry caterpillars have hairs that are at least irritating to the skin, so it is a good idea not to handle them too much. Up here in Michigan, we can afford to be a bit careless because none of the local species are really toxic, but I understand that some of the southern species (particularly the “puss caterpillars”) are downright venomous. Still, it’s not as if they are going to attack you like a wasp might, so keeping one should be OK as long as you don’t pet it.

  12. Brittanie permalink
    October 10, 2009

    This cutie looks alot like one I found at camp once.

    I love these things. So any updates on the fellow?

  13. October 12, 2009

    No updates on that particular one, we let it go after getting the pictures. We’ve seen a few more from time to time since then, so they’re fairly common here.

  14. Jeremy permalink
    October 19, 2009

    I believe it could be a “Giant Leopard Moth ” – Ecpantheria scribonia -check out

  15. October 19, 2009

    Jeremy: Thanks for the comment. All the pictures of giant leopard moth caterpillars on BugGuide show them having rather prominent orange bands between their body segments, though, so I don’t think that’s it.

  16. Jody permalink
    April 20, 2010

    I found a caterpillar like that last fall and have had it all winter. It has shed its skin twice, pretty much was dormant all winter, and then became really active suddenly a few weeks ago. I have been feeding it dandelion leaves, but have worried about whether that was enough or not since I found it in the street and not near its food source. A few days ago it crawled around and around, and then it settled into the dirt and old leaves . I’m hoping it is in a cocoon now. Is it possible that it will turn into a moth in the flimsy little bit of dirt and dead leaves that were in the bottom of its box? If I had known it would bury itself I would have put more dirt and fewer sticks in the box. I can’t believe I’ve kept it alive for nearly 7 months now, and I will be sad if it dies before I have a chance to set it free as a moth!

  17. April 20, 2010

    Jody: I found another one this spring, which we kept in a jar with miscellaneous grass and broadleaved plants so that it could pick and choose what it wanted to eat. It just made a cocoon and pupated just about the way you describe, including burying itself under some loose grass. I’ve raised a few other moths this spring successfully this way, so yours is probably fine. Mine spun a very flimsy cocoon, and made a pupa a few days afterwards, and that’s likely to be what yours does as well. I hope both yours and mine emerge as moths OK, then we can compare to see if they are the same thing or not.

    Incidentally, I’ve read that clean lettuce is often a good food for generalist feeders like tiger moth caterpillars.

  18. michele permalink
    August 19, 2010

    i am wanting 2 keep my one for a project and breed them but how do i do tha

  19. August 19, 2010

    I’ve only had a little success raising tiger moth caterpillars in general, and haven’t raised this particular species. Anyway, here are some sites that have general advice on rearing various types of tiger moths.

    I’d advise trying with more than just one caterpillar if possible, and try to raise them in individual containers maybe with slightly different conditions in each. You are likely to have a number of deaths until you work out the exact conditions.

    I’ve had a number of woolly caterpillars that I tried to raise that either died immediately after being caught, or that made pupae but never finished becoming moths. I think a big problem is moisture – if it is too dry in your cage they die of dehydration, and if it is too moist they get wet and evidently drown. Something I plan on trying next spring is to put about an inch of moist soil into the jars with a layer of dead leaves on top, so that the caterpillars can find the amount of moisture that they want.

  20. hytrewq permalink
    April 16, 2012


  21. June 1, 2012

    hey i caught one and want to know if it is poisonous??!!!!

  22. June 2, 2012

    emmy: No, not really. I wouldn’t eat one, the hairs are likely to irritate your throat and maybe get stuck, but there’s no particular harm in letting them crawl around on your hand.

  23. Mas permalink
    January 31, 2014

    So i found one in my house, and i put it to the four spiders i found while i was there. i returned the next day just to fin 2 spiders alive, 1 dead and pieces of the last one, wich this litle caterpillar had a leg in his mouth. so i have to asume he ate it, wich is impressive

  24. January 31, 2014

    Mas: yes, I gather that caterpillars are often not as herbivorous as we’ve been lead to believe. Some are prone to cannibalism if they are kept together in a crowded cage. And it sounds like yours thinks that spiders are a delicious treat.

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