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LONOMIA OBLIQUA: The Killer Caterpillar


There's Much in the Rain Forest Undiscovered

LONOMIA, the Killer Caterpillar

This is an interesting letter I have just received from an actual victim of the caterpillar and added to article.  I thought it so germane to the danger of Lonomia to head the hub with the report. 

"My name is Marianne: I am still interested in publications about the Lonomia Obliqua caterpillars that are found in Brazil and some other South American countries. Three years ago I was a victim of this caterpillar poisoning, ending up with haemolysis and acute kidney injury while in Brazil, after visiting Iguassu Falls. I accidentally touched a tree with my left hand and this resulted in a painful rash and swelling thereafter. I took a photograph for identification in case I had contracted something unfamiliar. It took another 3 days before I requested medical attention as the initial symptoms had cleared after a few hours.

Luck was on my side as I attended a medical conference and my local medical colleagues saved my life as they were able to contact the local public health office who then arranged for the antivenin to be delivered to the hospital I was admitted to obtain urgent medical advice .I like recommend the following website to anyone who may have been affected by a similar accident: www.cit.sc.gov.br This is the poisons unit of the Butantan Institute in Sao Paolo"

Full name withheld by author. Very sensible idea to capture an offending insect, or, in this case, to take photos of it.

We have known for ages many caterpillars can cause irritation by discharging body hairs, or can defend themselves by releasing vile-smelling secretions. Some are even known to be poisonous if ingested, along with the butterflies and moths they spring from. But until Lonomia came along we had not been exposed to a caterpillar able to release such catastrophic toxins that they could easily kill us.

Humans and Lonomia first attracted international press when an epidemic occurred amongst an agrarian community in Rio Grande du Sol, Brazil. Medicos were mystified at first after they received a score of patients with the same symptoms: haematoma and gangrene-like symptoms, spreading throughout the body, eventually causing massive blood leakage into the brain and, in several cases, death.

Snakebite, arachnids or giant centipedes were suspected at first, but no obvious bite sites were found and no patients reported being struck or bitten by one of the many venomous reptiles or insects in the rainforest. But gradually a picture emerged of people saying they had “just handled a bunch of leafy branches to break trail, or to gather vegetation for fires and shelter.” Doctors cautiously exploring the territory they had mentioned came across only one creature than commonly appeared, the Lonomia Caterpillar.

On examination, this curious caterpillar camouflaged itself by means of many plant-like hair-growths all over its body. (see last pic). Each tiny clump of hairs had a sharp, cactus-like spine sticking out which easily and painlessly punctured the skin of a human or predator that touched it. They had found the mysterious assassin…just a caterpillar.

Further studies isolated the agents in the toxins contained in a sack at the base of each spine. It was one of the strongest anti-clotting agents ever found in nature. Along with another protein which attached itself to the surface of the body’s cells, this caused all the body’s cells to leak like sponges as the blood was unable to clot, until the surrounding tissue was full of “bruised” blood; huge haematomas spread over the surface and the interior organs of the body as well as, eventually, the brain causing massive compression and brain death. In fact, more recent statistics reveal as many as 500 people or more have died as a result of coming into contact with Lonomia.

The investigators also found that the caterpillars were only dangerous if seized in numbers - rather like grabbing stinging nettles, or becoming a victim to the venomous spines of box jellyfish. To produce the deadly haematomas the victim would need from about 20 to 100 “stings” from the spines. Further, they found the caterpillars only appeared from two to three months of each year. As the symptoms could take a week or two to become serious, this is why the creatures had not been detected earlier; by the time someone was struck down, the caterpillars had ceased to feed on plants and had become pupae, disappearing from under investigator‘s noses.

An antivenin is now available, which has reduced the numbers seen in the clinics each season by more than one half. It was made by injecting horses with the toxin and drawing off the resistant cells to prepare the medicine. (I am unclear of the exact procedure, sorry). It has taken many thousands of caterpillars to make the vaccine each year, but the creature has made the most dangerous lists of world health authorities resulting in foreign doctors and health workers going to the area to help.

Most scientists think there are many other creatures “out there” waiting to be discovered with the potential to do harm and cause death to unwary humans straying in the environment. There are almost certain to be more venomous caterpillars, as they have not been seen as an extreme threat until recently and little is known about them as a whole. The evidence from my limited research to do this article is that there may be literally hundreds of venomous caterpillars around the world, several of which can do serious harm to man, especially if he is at all allergic to the toxins released when their spines are touched. The Lonomia family seem to be the worst, but there are some in the Southern USA, Mexico and the Americas, such as the so-called "Slug" caterpillars: Saddleback, Hag, Lo Moth and, the worst, Puss Moth. In fact the last moth larvae has caused several people to be taken to hospital with symptoms similar to Lonomia, although they don't result in death. The Hag caterpillar doesn't look like what we usually see, but looks more like a slow-moving arachnid or large tick. It is true to say moth and butterfly larvae, as a whole, remain virtually unknown and ignored.

This caterpillar is an attractive creature to look at, as so many poisonous and venomous life forms are: some because they want to advertise their presence in order to be left alone, and others which instinctively believe their reputation precedes them in the wilderness and are not likely to be molested, except by a hairless, weak, insensitive animal that has lost all remnants of jungle lore and survival it once possessed and knows no better. We all know who that is!

One thing about living in bland old Britain, we have few really nasty, venomous creatures to worry about, Peter Mandleson excepted.

Notes : The larvae, or caterpillar, from the family Saturnadae, are covered in urticating hairs (cause irritation and small pustules) as are many caterpillars. The LD50 of the toxin is about equal to some rattlesnakes. There are 12 or more species known at present, mostly in Brazil and Venezuela (Lonomia Achelous is more common in Venezuela as well as Obliqua). The anticoagulant properties are currently being explored by the pharmaceutical industry for use in human blood clotting problems. The toxin has also been responsible for kidney failure in some patients.





diogenes on April 24, 2018:

surprised they are coming indoors...we must be pushing too far into their territory. careful how you handle them


euripedes on April 22, 2018:

I´ve just found some of them in my house today. about 114 to be more precise.

diogenes (author) from UK and Mexico on July 17, 2011:

And thanks again for kind remarks...Bob

HRoger from Online where I can be! on July 17, 2011:

I sure will BOB, thanks for the tips!I sure don't want any of those creepy things crawling around me :D, once again, great hub!

diogenes (author) from UK and Mexico on July 05, 2011:

Hi HRoger. Lucky you, fascinating country. Keep away from the furry things! Bob

HRoger from Online where I can be! on July 04, 2011:

Wow fascinating! I just have to come back again!! Brazil is dangerous,, oh wait I am in Brazil! Reminds me of the Call of Duty Black Ops Requirements Brazil scenario! hehe


diogenese on April 10, 2011:

I know what you mean, but he couldn't breathe in there and there might be viruses! Bob

the pink umbrella from the darkened forest deep within me. on April 09, 2011:

i just keep finding more reasons to put my son inside a bubble!

diogenes (author) from UK and Mexico on March 23, 2011:

Thanks for comment, Peter...Bob

Peter Dickinson from South East Asia on March 23, 2011:

Fascinating. I will have to watch out if I ever go to Brazil. The moth itself is attractive. Thank you.

diogenese on February 23, 2011:

Lesson taken: don't be so serious, Diogenese! Send me a few of those seeds willya!? Bob

Ant from Africa from Tanzania on February 23, 2011:

Bob, I don't mean to blow my own horn, but we've tackled a crocodile before. It took us a while to turn him upside down, but we did it. Of course, we had to bribe him to play along, but it was fun.

diogenes (author) from UK and Mexico on February 23, 2011:

Ant. Not to be contentious, but large crocodiles and other saurians are killing and eating quite a lot of people in Africa. Thank goodness you don't have Lomonia to contend with as well!


Ant from Africa from Tanzania on February 23, 2011:

Although I do not fear the Black Mamba or Gaboon Viper, I do have respect for them. I dare say they fear us too. I mean, we ARE after all quite a large colony. Crocs? They won't mess with us, sir.


diogenes (author) from UK and Mexico on February 23, 2011:

hahahah. OK, Ant. While you're at it, have a word in the shell-like ears of the Black Mamba and the Gaboon Viper, not to mention the crocodiles!

Nice to hear from an African hubber...Bob

Ant from Africa from Tanzania on February 22, 2011:

Well, OUR caterpillars don't do that type of thing, as far as I know. And if they did, we'd give them a good talking-to.

diogenes (author) from UK and Mexico on January 24, 2011:

Thanks...will do...Bob

HRoger from Online where I can be! on January 24, 2011:

Wow.. great article! amazing content!

I could never even thought that caterpillars could be such killers :D

Really good info.

Hows your hubbing going? Really working out good for you?

Well I am new here , and just wanted to share a few hubs, when ever you have a chance, check them out.





Thanks friend.



diogenes (author) from UK and Mexico on January 13, 2011:

Thanks for that...but is it a mini-hub, or a comment?...Bob

2.el işmakineleri on January 13, 2011:

The caterpillar is the larvae (the baby) of both a butterfly and a moth. After around 2-3 weeks, the caterpillar builds itself into a cocoon where it remains a pupa for a further 2 weeks. The caterpillar then emerges having grown wings.

The moth caterpillar is well known for being a pest particularly in the fabric industry. One species of caterpillar has destroyed reams of silk in the far east, known in China as a silk worm.

Generally, most species of caterpillar are considered to be agricultural pests as they can munch their ways through fields of crops, often leaving enormous holes which result in unhealthy or inedible plants.

Some species of caterpillar are also highly poisonous, particularly those species that live in the tropical rain forests. Other species are only poisonous in their caterpillar form, meaning when they turn into a moth or butterfly, they no longer have venom.

There are more than 20,000 different species of known caterpillar found all around the world and it is estimated that there are many more that are undiscovered as new species of butterflies and moths are regularly found in regions where there is little, of any, human presence.

Caterpillars difference in size, colour and appearance depending on their species. Some caterpillars are very brightly coloured where other caterpillar species are quite dull-looking in comparison. Some species of caterpillars are very hairy, where others are very smooth. The main aim of the appearance of the caterpillar is to intimidate it's predators and to deter them from eating it.

The caterpillar, like the butterfly, is a herbivorous animal but the diets of the caterpillar and the butterfly are very different. Butterflies use their long straw-like tongues to drink the nectar out of flowers, which is an adaptation that occurs in the process where the caterpillar becomes a butterfly. Caterpillars mainly feed on leaves, plants and flowering plants and big holes can often be found in leaves indicating the presence of a caterpillar.

iş makinaları on January 13, 2011:

thanks for this comment very important information

billrobinson from CA, USA on December 14, 2010:

I find this an interesting post. Thanks for sharing this! Keep posting.

diogenes on December 09, 2010:

Yes, Astrid, you are quite right, the Megalopyge opercularis, or Puss Moth caterpillar (also known as the Tree Asp!!) can have a nasty effect on you if it "fires" its venomous spines into you. These are a voluntary defense mechanism and the creature must have seen you as non-threatening...as you say, petting one is not advised...Bob

astrid on December 08, 2010:

When I was little, I caught a Puss Caterpillar and played with it for hours. Intrigued that there were such adorable and oh so soft insects like it. Stroking its fur, never aware that there were poisonous stingers lying under it's fur.

Years later to learn that it was poisonous and it caused severe rashes and nausea, and even unconsciousness for hours on end. It never even let its stingers out.

diogenes (author) from UK and Mexico on October 18, 2010:

So glad the article helped a bit, Daniela; thanks for your kind interest...Bob I am going to look up the Park now on Google.

Daniela on October 09, 2010:

Hello. I really enjoyed your article. I work as a Biologist at Iguassu Falls, at Iguassu National Park. I´m researching about the Lonomia Caterpillar, because this is the season where they start appearing. I intend to inform everyone working here at the Park, so they can pass this message along to the tourists.

Thank you for the article!

diogenes (author) from UK and Mexico on July 31, 2010:

The adult moth of the Saturnid species possesses no active venomous defensive mechanism, as far as I know (which isn't far!) But it may be extremely unpalatable or even poisonous and may possess tiny urticating hairs - this is really just a guess. After all, the adult is really much of the larvae, physically Bob I will try to find out more and add a note on the hub

Ugolino on July 13, 2010:

Hi Diogenes,

Thanks for the fascinating article. Is the adult Lonomia moth poisonous too?

diogenes (author) from UK and Mexico on July 13, 2010:

Thanks all for comments. When I compiled this small article, I had no idea it would become the most read of all my hubs! I guess the implacable and deadly monster, regardless of size, holds us in thrall! Bob

starvagrant from Missouri on July 07, 2010:

I always like reading about critters. I have some hubs on leeches and octupi if you ever find the time.

WOW Website Design UK on July 06, 2010:

They really are to be avoided, their hairs even fly in the wind and can cause many problems to animals etc

diogenes (author) from UK and Mexico on June 29, 2010:

Thanks borge _009 and Stania. I have an article on hubpages on centipedes if you want to take a look. They can be nasty creatures, too...Bob

Slainia from Goderich Ontario on June 10, 2010:

Ok, to be quite perfectly honest this is both creepy and fascinating. Now I have to go look up venomous centipedes, which is...oh boy, it's horrendous. Anyway...thanks for making me unwillingly fascinated.

Great article, though.

borge_009 from Philippines on June 10, 2010:

Wow. I never thought there would be a specie of caterpillar like this, so dangerous. Great and interesting hub of yours diogenes.

diogenes (author) from UK and Mexico on June 09, 2010:

Thanks Alex,Derek,Monique...may all your caterpillars be of the bland kind! Bob

Alex on June 08, 2010:

Hello! I was born and raised in Rio Grande do Sul... As kids, we were always advised not to touch any trees when we went camping cause there deaths happening and they were still trying to find out what was going on.

Everything you said is correct. Thank you for the information.

shabi on June 08, 2010:

this is very informative account. thanx diogenes

Derek D from United States on June 08, 2010:

You learn something new everyday. Nature can sure pack a mean punch. Thanks for the informative Hub :)

monique stone on June 06, 2010:

and nice article!

monique stone on June 06, 2010:


diogenes (author) from UK and Mexico on April 06, 2010:


Thanks for kind comment. have used up my stock on the labor government at present! Stung them into calling election. Sorry to take so long to reply..Bob

diogenes (author) from UK and Mexico on April 01, 2010:

Thanks for kind comment IsadoraPandora

Isadora from Tennessee on March 27, 2010:

Awesome Hub! :-)

diogenes (author) from UK and Mexico on February 09, 2010:

Thanks, Lovelypaper! Bob

Renee S from Virginia on February 08, 2010:

I learned something new. Great hub. I really enjoyed it.

diogenes (author) from UK and Mexico on January 05, 2010:

Dear Moneypants: Caterpillars are probably the last of your worries...Bob

diogenes (author) from UK and Mexico on January 05, 2010:

Dear P? Aspirin? Buy in any chemist! Bob

Mrs. Moneypants from Canada and other places on January 01, 2010:

Creepy but interesting. I live in that general area so thanks for the info.

Larry Ray Palmer from Macon, Missouri on December 31, 2009:

Excellent hub. It's interesting to see that even a dangerous creature like this offers redeeming qualities in the form of new medicines. I was glad that you pointed out that it was being studied because as soon as I read that it produced a powerful anticoagulant, I started thinking "Hey, that would be great for those folks like my wife who have to take aspirin every day."

Lol... maybe I could even test the theory on a few people I don't like so there would be no need for animal testing... can you send me a few boxes to experiment with? :P

diogenes (author) from UK and Mexico on December 30, 2009:

Thanks for that. Yeah, nasty little critters, but no malice intended, purely defensive...Bob

Jerilee Wei from United States on December 30, 2009:

I've had all kinds of insect bite reactions and am thankful I've missed this one. Glad to be informed and very interesting actually.

diogenes (author) from UK and Mexico on December 30, 2009:

I lived on St George Island, Florida, some years back and also had a house for a short time in Atlanta. Know what you mean about some of those wild people down around the Appalachicola forest. They party hearty, shoot off 357's and loose the Rottweiler if you complain, have I got it about right? Thanks for comment...Bob

sgf468 from Columbus, GA on December 30, 2009:

Thanks for a really well written and interesting article. I live in middle Georgia and fortunately about the only deadly thing we have around our house is a next door neighbor.


diogenes (author) from UK and Mexico on December 30, 2009:

Hi emievil: I don't know which is your country, but there are nasty caterpillars everywhere except the really cold countries (not the killers), you only have polar bears to worry about there! Cheers, Bob

emievil from Philippines on December 30, 2009:

Wow, never knew there's a caterpillar that can be dangerous to humans. I haven't seen one here in my country but I guess it doesn't thrive here. Thanks for sharing this information diogenes.

diogenes (author) from UK and Mexico on December 30, 2009:

Hi Paul: Yes, that remark of mine was a bit tongue in cheek. Love the bull-bars and roll-cages! These Processional caterpillars are interesting me now and I'm about to do an article on them. "The runaway (caterpillar) train went over the hill and it stung!" Thanks for erudite comment...Bob

paul_gibsons from Gibsons, BC, Canada on December 29, 2009:

"I'm wondering if it has taken evolution a while to catch up in modifying some creature's behavior in order to accommodate and defend against the intrusion of man"....i think you give nature's ability and urge to deal with "intruding man" a bit too much credit here Diogenes... if that was the case we'd see an awful lot more animals with bull-bars and roll-cages around by now..

on the other hand it just may be a newly developed defense against hordes of amazone visiting, bushwacking scientists in search of biodiversity and undiscovered medicines as seems to be the latest fad... maybe you have a case... punctuated equilibrium all over again lol..

diogenes (author) from UK and Mexico on December 29, 2009:

Hi Stricktly. Yeah, that's the Doratifera vulnaris, it's hairs leave painfulk burning feeling. It's similar to the Processionary caterpillars. You also have a wasp larvae that looks like a caterpillar - the Perga dorsalis. It has a noxious secretion from mouth area but does not spit; niether do. But, hey, that's Oz, you're supposed to have all the nasties (I heard you say "Pomms") Thanks for comment Bob

StrictlyQuotes from Australia on December 29, 2009:

We have a Caterpillar here in Australia we call a 'Spitfire' it actually looks a lot like your pictures of the Lomomia, but it's more bright green in colour. They live on some of our native trees and as a child who loved climbing trees I sometimes got stung, they give a nasty sting but no further affects like this one you've described. I found your Hub very interesting!

diogenes (author) from UK and Mexico on December 29, 2009:

Thank you! Bob

carolina muscle from Charlotte, North Carolina on December 29, 2009:

Interesting hub, thanks!!

diogenes (author) from UK and Mexico on December 29, 2009:

Rose shrubs? Mysterious comment, Fiona. Mostly they are found in the Amazon rain forest. Not many roses down there I don't think..Bob

diogenes (author) from UK and Mexico on December 29, 2009:

Hi Dorsi. Yeah, you don't expect many life threatening probs with little maggots, do you? Thanks for post...Bob

diogenes (author) from UK and Mexico on December 29, 2009:

Hi Tonimac. Thanks for interest. There's lots in the world to be aware of, not the least is our fellows! Bob

diogenes (author) from UK and Mexico on December 29, 2009:

Hi Nicks: Yeah, They are interesting creatures, I may do a hub on them. You are probably talking about "The Pine Processionary Caterpillar." Very social insects and can be nasty in the latter stages of larval change. Thanks so much for your interest...Bob

Nicks on December 29, 2009:

In Spain, we have the procession caterpillar which can be dangerous to people with breathing problems as its hairs are poisonous. In fact, these caterpillars are known to kill dogs and cats should they inhale the hairs. As the name suggests, they can be seen in processions that can be three or four metres long - each one is green, fat as your thumb, joined by a filament to its partner and not very nice...

Tony McGregor from South Africa on December 29, 2009:

Fascinating - nature never ceases to amaze me! Glad I don't live anywhere near them, though. there are enough hazardous creatures around here as it is.

Thanks for researching and writing this interesting Hub.

Love and peace


Dorsi Diaz from The San Francisco Bay Area on December 28, 2009:

Wow!! I had never heard of such a caterpillar....I could see why it took them a bit to figure out who the venomous culprits were! Thumbs up - great hub!

fiona on December 28, 2009:

So... they just reside on rose shrubs? If not, wherelse?

diogenes (author) from UK and Mexico on December 27, 2009:

They are pretty much localised to that Amazon area, most of us would never come across one, thankfully. Thanks for interest...Bob

benny Faye Douglass from Gold Canyon, Arizona on December 26, 2009:

Wow, I didn't know they existed. Thank you so much for sharing. creativeone59

diogenes (author) from UK and Mexico on December 26, 2009:

No, Lita, not Lonomia, but you do have some fairly nasty larvae, too, so makes sense to take care. Best to wear gloves when gardening I think, in any tropical regions. You get some pretty nasty arachnids, including scorpions and a couple of venomous centipedes, too. Happy pruning! Bob

Lita C. Malicdem from Philippines on December 25, 2009:

I'm especially careful whenever I'm in my garden because of the likes of hairy caterpillars that cause skin irritation. I'll be particularly on the look out now, but I guess Lonomia isn't known here in the urban Philippines. Thank you for this interesting info.

Diogenes on December 24, 2009:

I'm wondering if it has taken evolution a while to catch up in modifying some creature's behavior in order to accommodate and defend against the intrusion of man. It just seems as if there are an awful lot of venomous and poisonous life forms being discovered every year of late. Interesting fact about the Recluse which I wasn't aware of. Thanks for your interest...Bob

C.J. Wright on December 24, 2009:

Nice work, very interesting. Kind of reminds me of the brown recluse spider. It was not discovered until the 60's when a child died from a bite.

diogenes (author) from UK and Mexico on December 23, 2009:

Hi Hi-Jinks: There's four caterpillers in Florida that have nasty urticating hairs. They are only really dangerous to anyone who has an allergic reaction to them. Otherwise, they usually cause irritation and rash...Thanks for your interest, I will add a section about them over the next few days. Bob

Hi-Jinks from Wisconsin on December 23, 2009:

Interesting. I heard there was also another caterpillar in Florida whose bit or sting will send you to the hospital.

diogenes (author) from UK and Mexico on December 23, 2009:

Hi HH: Yes, what a bunch they are. I'd sooner have a venomous caterpillar for company that pervy Pete. happy Christams! Bob

Hello, hello, from London, UK on December 23, 2009:

Wow, that was a revelation. Thank you for a very interesting hub. I could add a few more to the list where Peter Mandelson is.

diogenes (author) from UK and Mexico on December 23, 2009:

Hi Bill: Yes, seems like there's quite a few around apart from the deadly species. Makes sense, really, otherwise they would be fat, tasty morsels for birds and other predators. Thanks for interest...Bob

William R. Wilson from Knoxville, TN on December 22, 2009:

I once got a stinging caterpillar in my sleeping bag. Not pleasant. Luckily it was only mild irritation, no hematomae!