The Day It Rained Caterpillars

Live Oak Tussock Moth ~ Orgyia detrita

Inchworms move more quickly than you might think. Intent on trying to photograph patterns on an especially tiny one trucking along a boardwalk at the San Bernard Wildlife Refuge, I assumed a twig had fallen into my hair, and brushed it off. Then, as I brushed away a second and third ‘twig,’ I realized they weren’t bits of a tree branch at all. They were caterpillars.

As the wind rose, the number of falling caterpillars increased, until the boardwalk was covered with them. In only a few hours, hundreds of them were crawling over plants, the decking — and me.

Eventually, I learned I’d encountered the Live Oak Tussock Moth (Orgyia detrita), a moth species whose life cycle coincides with the emergence of Coastal Live Oak leaves in spring. Quercus virginiana serves as their primary host plant, and emerging caterpillars may completely defoliate a tree, although wind-blown Tussock Moths may defoliate other small trees and shrubs; all of the oaks and other plants usually rebound without suffering permanent damage.

The caterpillars, named for the ‘tussocks,’ or tufts of hair on their back, are strikingly pretty. Those tufts are so striking that, when I spotted this caterpillar on Pete Hillman’s nature blog, I suspected his English caterpillar was related to the species I’d found in mid-April.

Vapourer or Rusty Tussock Moth ~ Orgyia antiqua

Indeed, it is. Known in the United Kingdom as the Vapourer, in the United States the non-native species is known as the Rusty Tussock Moth. Like our Live Oak Tussock Moth, the Vapourer feeds on a variety of broad-leaved trees and shrubs throughout woodlands, moorlands, valleys, and urban gardens from northern Scotland to the extreme southwest of Cornwall.

While the Vapourer shares the distinctive hair tufts of our Tussock Moth, its common name refers to the pheromones — the ‘vapours’ — that males follow to find females with which to mate.

The hairs of both species can be irritating to human skin, but there was nothing at all irritating about finding myself in the midst of a caterpillar ‘shower,’ or in the discovery that our native species has an equally attractive counterpart across the Atlantic.

Comments always are welcome.

71 thoughts on “The Day It Rained Caterpillars

  1. What a strange experience and sight that must have been! (Probably for the caterpillars too.) I’m glad they didn’t irritate your skin – could have been unpleasant if you had bare arms or legs!

    1. I may not have had enough contact with them for irritated skin to be an issue; it was easy to brush them off my hair. Now, ask me about the fire ant mound I accidentally stepped into later that day. The caterpillars are easier to get rid of, that’s for sure.

    1. It sounds like our mothers would have gotten along just fine, at least as far as stray ‘critters’ were concerned. The good thing about having one drop down from a tree is that they brush off easily — at least, they do if you’re aware that you’ve become a ‘host’ for them.

  2. Tussock moths are common here too and as you point out their hairs can be quite irritating and some people react to them more than others. My wife develops an itchy rash for days if she happens to make contact with them.

    1. The variability of human responses to natural irritants is interesting. I despise mosquitoes, but their bites rarely linger for me more than a few hours. On the other hand, a friend can count on their bites lasting a full week, and being both painful and annoying for the whole time. I’m sorry Miriam is so sensitive to these. I suspect they’re not always as easy to spot when it’s only individual caterpillars that are roaming around.

  3. I smiled when I saw the image, then giggled when I read the text….. only you could have had this experience.

    1. Even if it was raining, at least it was only a minimal shower. I’d hate to think of a caterpillar hurricane. It certainly was interesting, although in the end it meant no photos of the inch worms. They were even cuter: about a half-inch long, with yellow and black patterning. I’d always asssumed inchworms were plain green, but not so.

    1. It wasn’t precisely scary, but it certainly got my attention. One caterpillar can be pretty, or interesting. A few of them raise questions, like “Are they going to eat up my garden?” But so many, all at once, raised a different question: “What in the world is going on?” At least I found the answer, eventually.

    1. You and me both. I’ve had one direct encounter with an asp, and once was enough. Immediate and intense pain hardly describes it, but at least I didn’t end up in the ICU. A neighbor who lived in Galveston at the time got a good dose, and it affected her ability to breathe.

  4. Some people aren’t allergic. Perhaps you aren’t. My husband recently had a brown-tail caterpillar on his hand. Many, many people are allergic, and get a terrible rash from them. Fortunately, not my husband.

    1. The multitude of plants and animals that can leave their marks is far greater than most of us realize.The worst/most dangerous encounter I experienced took place on a boat, when a brown recluse decided to munch on my leg. In a day, my leg swelled to twice its normal size, with red streaks running in every direction.At a nearby storefront clinic, the physician recognized it for what it was and kept me out of the hospital. I didn’t lose much flesh, but I do have a little depression that serves as a reminder.

  5. I’m sorry I missed the caterpillar show, but I can see you in my mind’s eye as you calmly step back, watch and record while many people would be hopping around, screaming and slapping at their hair and shoulders. And those tufts are striking.

    1. It was quite a sight. Some group behaviors — migrations, murmurations, the emergence of cicadas — are familiar and even sought out, but it never had occurred to me that caterpillars might behave in a similar way. I’ve wondered whether our February freeze might have been responsible, directly or indirectly. For example, our crape myrtles have had an astounding bloom this year. It was a little late, but I’ve never seen such enormous collections of flowers, and they’ve never lingered so long. Perhaps a late flush of growth on the live oaks aided and abetted the development of so many caaterpillars.

  6. Oh gosh! I think I’d have been a bit squeamish to have them falling all around me. And the asp! I almost wish I had not read the comments to find out about that experience!

    1. Apart from the pain they inflict, one problem with our asps is that they’re so darned cute. They’re fuzzy, and invite touching, and children of all ages can be tempted to ‘pet’ them. Unfortunately, it only takes brushing up against one to get the full effect of their defense system. Since I didn’t know tussock moths also can irritate, I was more interested than apprehensive when they showed up. If I am sensitive to them, the contact must have been so incidental I wasn’t bothered.

    1. They would suit the Art Car parade, wouldn’t they? Everyone’s talked about how lush some of the growth has been since the freeze (think Crape Myrtles), so it makes sense that some critters might rebound in the same way. Your mention of Alice brought back memories of Grace Slick, Jefferson Airplane, and the ‘hookah smoking caterpillar’ that was part of the “White Rabbit” lyrics. Good times.

    1. You’re not alone. I didn’t like them on me, either — but I sure wasn’t going to miss getting a photo of one! I still regret not getting a decent photo of the inchworm. That tiny critter was really cute.

  7. Better you than me, Linda! Not sure I’d have enjoyed having one of these hairy critters in my hair. But hey, you got some great photos and learned about this one’s kin across the pond, so all wasn’t lost, right?!?

    1. Thank goodness they fell ‘on’ my hair rather than crawling into it. It made getting rid of them quick and easy. It might have been even faster if I’d realized at the beginning I wasn’t dealing with twigs. Finding its ‘relative’ on Pete’s blog was great fun. As I sometimes say, familiarity doesn’t always breed contempt. Sometimes, it brings recognition.

  8. What an unusual experience, one that I’m sure you are uniquely qualified to enjoy and welcome for it’s photo opportunities.

    1. There are a lot of entymologists in the world who’d probably have been really happy for such an experience, but at least I’ve come to the point in my life where I could appreciate it. I grew up with a mother whose response to any sort of insect was revulsion, so I’ve had a lot to unlearn over the years. In truth, it wasn’t until I became interested in native wildflowers that my interest in insects began to develop. The number of insects populating our plants is enormous.

  9. How interesting! I think I would have been a tad freaked to be “attacked” by a caterpillar rain! The photos are terrific and I had no knowledge of this caterpillar til today so I learned something new!

    1. I figured you must have an Orgyia species up there, and sure enough, you do. It’s Orgyia leucostigma, or the white-marked tussock moth. You don’t have the oaks that our species favors, but you do have a variety of pines, and the white-marked tussock moth shows up as a pest at — Christmas tree farms! It seems there’s a species for everyone. Can’t you just see Oprah pointing and shouting, “You get a caterpillar! and YOU get a caterpillar!”

    1. How could I have missed adding a link to the B.J. Thomas song: “Raindrops keep falling on my head”? I just looked at the lyrics, and grinned. They include the line “I’m never gonna stop the rain by complainin'” — the same holds true for caterpillars, it seems!

  10. These are some fancy fancy characters! They look like they’re duded up for a parade. I guess a sky-diving competition instead. I’ve had caterpillars drop on my head once in the while, but never a shower of them. I have been hearing the quiet pitter-patter on the tree leaves, telling me there’s a lot of gypsy moths caterpillars overhead, dropping bits of leaf and…other stuff. I don’t know if I learned the word from you, but when I think about caterpillar excrement in my hair, I think “Frass!” as kind of a substitute cussing.

    1. I first came across ‘frass’ on the BugGuide site. They offer a bit of explanation about the word itself: it’s derived from German frass, which is the past tense of fressen – “to eat as an animal does” They go on to add that the word was borrowed into English from the German entomological literature in the 19th century.

      What’s really amusing is that they titled one of their sections “Frass,” and added this note: “Frass is insect debris and this section of the site is a humorous reference to that. Poor quality images, images from outside North America, north of Mexico, and those that otherwise do not add value to the Guide are moved here. Frassed images will remain here for 30 days after the most recent activity so that comments may be viewed. After that they are automatically removed by the system.”

      So, if you submit a truly crappy image to them, you’ll get frassed!

  11. Covered with caterpillars! What a thing, but I’m glad you observed and shared with us. They’re so pretty, these spiky, fuzzy, colorful critters!

    1. They really are pretty, and the similarities among the species are both striking and, I assume, predictable. They all have those little tufts of hair that resemble the tuffet that Little Miss Muffet sat on: although the original meaning of ‘tuffet’ seems to be a discrete mound of grass. I’d far rather have the caterpillars than a rain made up of the spiders that came to sit beside Miss Muffet!

      1. I didn’t even think about Little Miss Muffet and her tuffet. My own caterpillars, the Pipevine Swallowtails, are creating their cocoons all over the house! The vine is off of out back patio, but I’ve seen a good half-dozen under the eves of the roof, by the back door (which I posted about), and on Plateau goldeneye plants even further away. And those are the ones I’ve spotted. The garden has regular black and blue adults flitting through, so lovely to see.

        1. Lucky you, to have those swallowtails! They’re beautiful creatures, and I always enjoy seeing them, although I rarely see one of the Pipevines.

  12. From Orgy[ia] to “the vapours” in a post about moth larvae: who’d have expected that? The latter term searching me searching, and I turned up the following 1895 passage from an article in the original Life (not the magazine of the same name we grew up with):

    “In the days when our fathers wore wigs and our mothers affected powder and patches it was the mode for ladies to be afflicted with what was called ‘vapors.’ Judging from the meager details furnished by the physicians of those days, the ‘vapors’ must have been Pilgrim Fathers of the ‘tired feeling’ and ‘goneness’ so numerous in the midst of the sex to-day. Poor and humble folk might have such ailments as ‘rheumatics,’ ‘fever and ague,’ and ‘bile,’ but a wealthy and fashionable woman alone could afford vapors.”

    1. It’s a terrible image because I pulled it off a YouTube video, but the first thing that came to mind when you mentioned ‘the vapors’ was this, from the PBS Mystery! series. When I was growing up, references to ‘the vapors’ still were around, but the word was used in a mostly humorous way: a bit of a joke about a certain ever-so-sensitive personality type.

      As for the ‘orgy’ that’s included in the genus name, that makes a certain sense. The female are flightless; they just pick a spot, send out their ‘vapours,’ and wait for the males to show up. I can’t find it now, but somewhere I came across a photo of a female with a number of gentlemen callers: a veritable orgy of caterpillars.

  13. To many folks I would have thought the prospect of being showered by hundreds of hairy larvae would be much like a freakish horror story, so full kudos to you, Linda, for taking it in your stride and for getting this excellent photograph! It is a real beauty, too, and I can see the relationships between species on opposite sides of the pond. When I see these marvellous caterpillars I can’t help but think of modern toothbrushes with their longer bristles, but I would not fancy putting one of those between my gums … especially with all that irritation!

    1. As I responded to comments, I started looking at different areas of our country and discovered just how many Orgyia species there are. Colors vary, but those little tufts seem to be standard equipment, and they sure are cute.

      I was grateful that the caterpillars came as a shower and not a storm. Since they were falling relatively sporadically, the total numbers grew, but there weren’t so many at a time that I couldn’t brush off the ones who made a bad landing on a human. Like the inchworms, they were fast on their feet once they made ground; after all, they had business to attend to!

    1. The fire ants always are annoying and painful, but for the most part I manage to stay out of them, and the ‘fire’ in their bite usually lasts only a few minutes for me. I do wear knee-high boots a good bit, even if I’m not going to be in water. If I step into a nest that’s hidden beneath grasses, it gives me a chance to notice them and brush them off before they bite. What I truly hate are the chiggers; the itch they cause can last for days.

      1. I’ve done a tiny search on ‘chigger’ but I’m confused by getting a variety of insects mentioned. What do you call a ‘chigger’?

        1. Here you go: just about everything you’d need to know about Texas chiggers. The advice to spray down clothing with Sawyer’s Permethrin is a good one. It protects against ticks, mites, and mosquitoes as well as chiggers, and will last through several washings. I add Sawyer Picaridin spray to the mix; it’s for mosquitoes and really does the job. As a bonus, it won’t hurt equipment like cameras or binoculars.

  14. Unfortunately, vast areas in Colorado Springs are suffering from an infestation by a relative of your oak tussock moth. The Douglas-fir tussock moths destroyed large swathes of trees in the foothills a few years ago and could only be stopped by spraying. Now they are back and have bred in one of our conifers, which looks very sad. By the time we noticed, all arborists were booked out a full month. Not sure the tree can be saved.

    1. Until I found this species, then Pete’s, and began looking around, I didn’t realize there are so many tussock moth species: each with their particular host plants. It’s a shame that they’ve reappeared in your area, and that one of your trees is suffering their predations. Your mention of fully-booked arborists reminded me of the situation here in April and May. After our February freeze, it took some time to sort out what would live and what would die, but once those determinations were made, you couldn’t get an arborist or tree service for any amount of money. I hope you’re able to get whatever assistance you need, and soon enough to save the tree.

      1. Thanks for the good wishes. I hate the idea of using insecticides, as the majority of our insects are beneficial and I don’t want to run the risk of killing even one butterfly. But I hope there is a targeted way to stop the destructive ones.

        1. Well, as the saying has it, sometimes we need to avoid letting the perfect be the enemy of the good. Constant cost-benefit analyses can be wearying, but they’re important.

    1. I can’t say I was comfortable with it –but at least they brushed off easily, and once I saw how attractive they are, there was no way I was leaving without a photo!

  15. These are great photos! We are seeing tree damage in the forests from the Douglas fir tussock moth that looks quite a bit like your moth. Very pretty, but harmful.

    1. Another reader who lives in Colorado mentioned that the Douglas fir moth is wreaking havoc there, and I read that a different species has caused damage at Christmas tree farms in the upper midwest. It’s a good reminder that it isn’t always the invasive species that cause problems; still, that doesn’t make their munching any more desirable! It was interesting to read about the cyclic nature of your infestations.

  16. I think if it was raining caterpiggles, I’d want a bumbershoot, out of deference to both the caterpiggles and to me. This critter looks like an animated cactus.

    1. Apparently its hairs can be just as irritating as the spines and glochids of a cactus. At least the cacti stay put, which puts the responsibility for avoidance on us.

    1. I suppose the good news for you is that these are attracted more to trees than to gardens for their host plants. Roses and such have enough problems without these moving in.

  17. I envy your shower. I love caterpillars so it would be a welcome experience. I had a similar caterpillar, the White-marked Tussock Moth, crawling around on my camera bag a few years ago.

    I sometimes experience a different type of caterpillar shower…Frass! Every few years we have Gypsy Moth outbreaks which defoliate our trees. There are thousands of them and they do literally shower you with frass as they eat. If you are quiet while in the woods and under a tree you can literally hear a shower of it hitting the dried leaves on the forest floor. I prefer yours.

    1. Now I remember your White-marked Tussock Moth. Looking at the photos, I’m wondering if the tufts on yours were actually so much whiter than this one’s, or if it was a difference in lighting. Both, maybe. Yours seems to have thicker tufts, too, which could be a function of any number of things. In any event, what we were saying about the number of species certainly holds true. I’ve ‘met’ at least a dozen varieties of tussock moth in the past few days, and all of them are busy defoliating different hosts.

      I mentioned to Rob my perplexity when I had a photo ‘frassed’ on BugGuide. That’s how I learned about that.

      1. I’ve had a few frassed also. Yours probably were considered superfluous maybe. I am sure they were recognizable shots. That’s happened to me. I don’t understand why though as some species have hundreds of examples. Can’t complain about “free” though.

        They are that white. It was natural light and not flashed. I’ve shot a few milkweed tussocks but haven’t shared them yet. I am not seeing as many caterpillars as I used to. Maybe part of the “insect apocalypse”.

    1. I’m quite taken with those little tufts. The colors and the arrangement of the little dots and such differs from one species to another, but all of the Tussock Moths have the tufts. It seems that the collective noun for caterpillars is ‘army.’ These certainly were on the march.

    1. Here’s a stray thought: the ones most likely to fall on us are the ones that prefer trees as a host plant. I wouldn’t want Monarch caterpillars in my hair, either, but at least they’d be easier to find than they are in the wild, munching away in the shrubbery.

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