woolly bears on the move

These aren’t brand new photos, but I’ll use them to illustrate this post. Lately, I’ve seen several Woolly Bear caterpillars (Pyrrharctia isabella) moving about over the dead grass in the garden and surrounding fields. Unfortunately, I haven’t been carrying my camera around with me so much, so you get the vintage photos instead. Anyhow, about these Woolly Bears. Each time it warms up just a little, the caterpillars are on the move once more. I made a note on March 15th, that I saw one on the path through the meadow beside the barn on an afternoon when the temperature was -4C (25F). I’ll be watching for them over the next few days and may collect 2 or 3 to keep in a container to watch while they cocoon. I may do a bit more of that kind of thing this year if I have the time.

It’s interesting how these caterpillars move about even when it’s quite chilly. Obviously, they are fairly cold resistant as they seem to be sheltered in the grass over winter and must become quite frozen when the snow and ice pile up. In Caterpillars of Eastern North America, David Wagner states that they overwinter as nearly grown caterpillars, and usually feed a bit more in the spring before cocooning. They can eat most kinds of leaves and grasses, so they don’t have too much trouble finding something to eat, even early in the season when most plants are still dormant.

The adult of the Woolly Bear goes by the common name of the Isabella Tiger Moth (Pyrrharctia isabella). It’s not all that unusual for caterpillars and moths to have different common names even though they are of the same species. You will see that quite a bit with the Sphinx moths. Most of us are familiar with the big caterpillar known as the Tomato Hornworm, but less would know that, as an adult, it is known as the Five-spotted Hawk Moth (Manduca quinquemaculara). Yet another reason why scientific names are so important, particularly when discussing insects as they have so many different descriptive names that things can be quite confusing. The adult Pyrrharctia isabella is quite a beautiful moth — yellowish with small markings (see below). It’s not quite what one might expect as the adult form of these fuzzy brown and black caterpillars!

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7 Responses to “woolly bears on the move”

  1. Cathy Says:

    Dang! I always wondered what the wooly bear morphed into. I just showed my husband. Hmmmm. I wonder why we see so many caterpillars, but not the adults. Is it a day/night thing? I wish the tomato horn worm didn’t repulse me like it does. Shudder. I hated coming upon them when I grew tomatoes. They about drove me from my tomato patch. My macho neighbor threw them against his stockade fence. More shudders.

  2. John Says:

    Bev, Cathy’s post makes me wonder: only when I grow tomatoes do I see the tomato hornworm (I didn’t even know that was the common name, but I’m sure by the name that it is the same ones I see when I grow tomatoes). Why is that, and how in the devil do they remain completely, utterly, hidden (or are simply not there) except when I grow tomatoes? Do you know? It’s often puzzled me.

    Back to your post; I look forward to seeing those photos of yours as the caterpillars you collect later cocoon.

  3. burning silo Says:

    Cathy – It’s partly the day/night thing, but also that caterpillar mortality is actually rather high. So many birds eat them, and there are also a lot of parasitoids that kill them. And then there are other insects — the stink bugs are real killing machines and I find many dead caterpillars while doing my insect patrols. In a newspaper article, David Wagner who wrote Caterpillars of Eastern North America said that only a fraction of the caterpillars ever make it through to being moths. Having observed the Monarch caterpillars as much as I have in the past, I’d have to say that’s very truel. Regarding Tomato Hornworms, a few years ago, we had some city folk staying here for a couple of weeks. They found hornworms eating the white nicotiana in my garden and I heard them shrieking at the sight of them. Of course, as you might guess, I’m not all that displeased to find caterpillars in my garden. I see “photo op”!!! (-:

    John – The tomato hornworm can eat other host plants as well, so they probably just munch on those. The moth would just go around laying eggs on suitable vegetation, so if you plant tomatoes, the moth will soon find them and deposit eggs. Caterpillars grow *very* past, so they can go from tiny creatures that barely inflict damage, to jumbo cats that strip all the leaves off of a plant.

  4. Wayne Says:

    I love finding woolly bears, but they’re not all that common around here. I recall hearing from several folks around here that they watch the woolly bears and if they have more “fur” it means a colder winter. Now, I’m just not real sure about evaluating the amount of fur on a woolly bear, but if true I take my hat off to such observational powers, however predictive it may or may not be.

    Speaking of winter-active arthropods, and I don’t imagine it’s a problem (yet) in Ontario, we can get ticks any time of the year. I didn’t even bother to blog my first tick of the season, way back in January, because it was so soon after the previous one, in December. Experiment: go out here on a warm day in winter, sit down in a vegetated area for an hour, and you will probably get a tick.

    It sounds worse than it really is. Except in mid-spring to early summer, when the population is really high, I get few ticks actually biting in, but just because I do the socks over the long pants thing, and spray my shoes and socks with cutters or off or something after it gets permanently warm. That probably reduces my problem 99%.

    We have at least two species of ticks – dog ticks, the large ones with the white spot, and the much much smaller deer ticks, that can (but usually do not, depending on where you are) harbor Borellia, the bacterium that causes lyme disease. Here we don’t have that problem (yet).

    Funny story, since ticks are so sluggish: we had a visiting Norwegian colleague who stayed with us for a few days during a conference here. We went on a hike in May, and he found a tick crawling up his arm. I’d just grab it and smash it – he panicked and waved his arm around like it was a hyperactive wasp. No fault, I supposed they don’t have ticks in Norway. Or chiggers in England.

  5. burning silo Says:

    Wayne – I have begun to wonder if some of the Woolly Bears that people see are earlier or later instars. David Wagner has a little note about that in Caterpillars of Eastern North America – that the hair covering and amount of black and brown hair changes a bit in each instar.
    Interesting to hear about the ticks there. I was just wondering about that a couple of days ago when looking at the progress of the vegetation at your place. Do you ever find ticks on the cats that like to go out walking with you — and do you have to do anything to keep them off? This may well become a bit of an issue for us here at the farm as you’ll remember that I found the first tick ever on Sabrina last summer. We can’t put her on the usual systemic type treatments that people use for fleas and ticks as we had to do that four years ago after she picked up fleas after a trip where we stayed in motels, etc.. and she got very sick from the treatment. We started her on a different product a couple of years ago and it was the same thing. Apparently, such reactions are more common in Collies than in many other breeds. Anyhow, I suspect we’re going to have a problem on our hands before too long.

  6. mon@rch Says:

    Always love finding the woolybears! I have never had a chance to photograph the adult!

  7. burning silo Says:

    mon@rch – I’ve only photographed a couple of adults. I’ll try to get some better photos this summer.