Summary: Caterpillars are brightly colored or camouflaged to protect themselves from their predators. Some caterpillars have hairs or spines that are loaded with poisons that will give you a painful sting if you touch them. Resist the urge. I have been stung myself and it is no fun.
Caterpillars are the larval stage of butterflies and moths. They are often brightly colored and they feed on the foliage of many different kinds of trees and shrubs. Caterpillars have developed defense mechanisms that protect them from predators. Their bright colors serve as a warning sign to potential predators telling them to beware of toxic treats. Caterpillars are sometimes covered in hairs or spines that are venomous and can easily break off if you touch them causing joint pain and swelling. Even caterpillar cocoons can be unsafe to touch.
Some caterpillars have hairs or spines as that only mimic their more toxic cousins. These caterpillars are not toxic, yet fool their predators by looking like the more toxic variety. Because caterpillars are so good at fooling their predators, it is very difficult to determine whether a caterpillar is or is not toxic just by looking at it. The only way to find out for sure would be to touch it, which is sort of a bad return on investment. Caterpillar stings can cause welts that last for weeks, and some species of stinging caterpillar can even cause death. Caterpillar venom is not usually considered deadly, although small children might be at serious risk if they pick up a brightly colored caterpillar and eat it, thinking it might taste good.
Although the great majority of caterpillar species are not toxic I would recommend being cautious by avoiding touching any caterpillar, especially the brightly colored, hairy varieties that look so cute and cuddly. Many caterpillars that do not actually produce venom can still cause an allergic reaction because their fine hairs disperse in the air and can be breathed in or irritate human skin. Even the bristles on the relatively harmless and sometimes domesticated wooly bear caterpillar can cause skin irritation. And, you don't touch a dead or slightly smushed caterpillar, either. They have just as much toxin in their bodies as living caterpillars.
Caterpillars will sometimes explode in numbers during certain times of the year, and some years there are more caterpillars than others. Children should be warned about the dangers of touching them if there are a lot of stinging caterpillars outside. When examining for stings look for a row or several rows of red insect bites. They can last anywhere from a few days to several weeks and have varying amounts of pain or soreness.
Here are some different types of stinging caterpillars, what they look like, where they are found, what they like to eat, and what you can expect if stung by one.
Saddleback Caterpillars are brown-red in appearance, about 2 cm long. They have fleshy horns with spines on each end of their bodies and shorter horns with spines on each side. They have a distinct green coloring on their midsection that looks like a saddle. There is a brown or purple circle in the middle of the bright green saddle section. Saddlebacks are common across North America and frequently appear in late summer or early fall. They feed on apple, basswood, cherry, chestnut, dogwood, elm, maple, oak, plum, and corn.
Gypsy Moth Caterpillars are a blue green color as young caterpillars. Their color fades to a blue-grey as they get older. They are covered in spiny, stinging hairs and have round bumps on each of their body segments. They are blue behind their head, red on their rear, and yellow on the sides. The gypsy moths usually exist in low numbers, but outbreaks can be major factors in the defoliation of trees so they are considered a pest beyond their stinging potential. During times of outbreak, the gypsy moth caterpillar droppings and the sound of their chewing is also an annoyance. They were brought to America in the mid 19th century to begin a silk industry that never materialized. They are now entrenched as one of the most harmful pest to hardwood trees in North America.
Hag Moth Caterpillars are brown or red-brown and only a centimeter or two in length. They are covered in hairs and have nine pairs of spines running down their back. Some of the spines become twisted together so the caterpillar looks like it has locks of dirty, tangled hair, earning them the name Hag. They deliver a painful sting similar to the saddleback caterpillar. They are found in the Eastern and Southern US, prominent in August and September, and feed on apple, birch, chestnut, dogwood, hickory, oak, sassafras, and willow.
Tussock Moth Caterpillars in their many varieties, are hairy and brightly colored with long hairs on both of their ends. These hairs are often in clumps, or tufts, giving the caterpillar its name. The hairs break off very easily and cause skin irritation. There are many varieties of tussock moth caterpillars that feed on a wide range of plants. One example is the aptly named toothbrush caterpillar, which has several venomous, toothbrush-like bristles on its back.
Puss Caterpillars are pear shaped and covered in long, shaggy looking hair that is dirty white to a yellowish brown in color. They are found throughout North and South America. The hair on their back ends looks like a tail but hides venomous spines. These caterpillars look very soft, like a tiny Persian cat, which is probably how they got the name “Puss”. However, despite their fluffy appearance these caterpillars give a particularly nasty sting that often develops into a persistent rash. They are communal feeders on apple, elm, hackberry, maple, pecan, oak, sycamore, and citrus trees. They sometimes fall from trees and land on people, giving them sharp stings on their necks or arms. Sometimes a severe reaction can occur from a puss caterpillar sting. Symptoms might include headache, fever, nausea, vomiting, respiratory distress and in extreme cases seizure and abdominal pain. Their stings have a grid-like pattern that can last for several weeks.
Browntail Moth Caterpillars are hairy brown caterpillars 2 or 3 cm in length with red spots on its back and white hairs on its sides. Their hairs can easily break off and cause irritation to the skin... They are distributed worldwide and feed on blackthorn and hawthorn shrubs, as well as on fruit trees, mistletoe, and many other deciduous trees.
Buck Moth Caterpillars often increase in numbers during the fall hunting season, which is how they got their name. They have breakaway spines on their back and sides and have a sting similar to the saddleback. They have a dark red head, grey-brown body, yellow and white spots and orange spines on their back and longer red or black spines on their sides. They are found in oak trees in the Southeastern and Southwestern states. I think this was the kind of caterpillar I was stung by. The red, rash like bumps last about a week and feel tender and painful.
South American Lonomia Saturniid Moth Caterpillars are a dangerous group of caterpillars that inflict very painful stings that can cause internal hemorrhaging, renal failure and for several unlucky victims each year, death. They have camouflage colors of green or brown that helps them to blend into their environment. They are communal feeders that sometimes gather on the trunk of trees where sometimes an unwitting, unfortunate soul leans against them and gets severely stung. The benefit of these insects is that they have provided scientist with chemicals that help to prevent blood clots. They are only found in South America, but I'll tell you about them because you are better off knowing, than not.
Other stinging caterpillars include the Io Moth Caterpillar, the Silverspotted Tiger Moth Caterpillar, and the Stinging Rose Caterpillar. This is not meant to be a complete list, but a list of some of the common varieties you need to watch out for in North America.
If you see a caterpillar crawling on your skin do not rush to swat it off because this could cause spines to get stuck onto your hand. Gently lift the caterpillar off with a stick or pencil. If you are stung by a caterpillar don't rub the affected area, this might cause spines to become more imbedded in the skin. Take a piece of sticky tape and try to pull out any hairs or spines by placing the tape on the skin and pulling it off. Do this several times until all the spines are removed. Wash the area with soap and water. If you are stung on the hand you should remove any rings immediately because the fingers might swell up. To easy the sting you can place an ice pack on the sting site, rub alcohol or ammonia on it, rub on an antihistamine or cortisone cream or take a antihistamine orally.
To prevent caterpillar stings you need to be aware of when the caterpillars are in their peak larval instar season. This is normally late fall, but can also occur in the spring in tropical climates. The caterpillars will be around in greater numbers during this time. You might want to wear long sleeves and a hat with a wide brim if you are walking outdoors under a lot of trees with caterpillars in them. Also, the hairs of a caterpillar can be spread into the air and cause allergic reactions in some people. Keep your windows and doors closed and make sure you have clean air filters on any air conditioning system that brings in air from the outside. Don't hang wet clothes out to dry because hairs or spines might fall onto them.
Caterpillars are beautiful, interesting creatures that develop into harmless moths or gorgeous butterflies. Look but don't touch is my best piece of advice.
09 Apr 2012, 15:42
I was just stung by a cat-pillar of unknown species. it left two "hair"
like "thorn" looking things in my hand. about 1 hour later my whole hand
turned into a "ballon". Later the right hand of my face was EXTREEMLY
swollen then later the left. Long story short I ended up in intesive care
with my throat swelling shut. Had I not got care when I did, I would not be
writing this e-mail. Just got home from the hospital after 3 days in
11 Apr 2012, 14:14
I was stung by a buck moth caterpillar on Monday, April 9th, around noon.
My only remendt was a frozen gel pack to sooth the sting. I have been stung
by many different insects and other things that never lead to an allergic
reaction or hospita visit. This is by far my worst sting from a
caterpillar but seems to be getting better. The skin raised, turned balck
and wasvery sensative the first night but there were no other symptoms. I
did and still feel fine - no nausea, fever, etc. If the mark on my skin
and sensative area surrounding the mark is getter smaller evry day, is it
basically healing? If I have not had any other reactions to the sting at
ths point, is there any chance it can still turn for the worse?
26 Apr 2012, 19:17
I got in contact with a Io moth caterpillar 3 weeks ago on my shoulder. I
developed big welts and lots of pain. The welts were gone after a while but
I woke up the next day with swollen gland on my neck. I got another swollen
gland on the other side on my neck. Any ideas? My doc didn't gave any im
portance to the carterpillar and instead gave me antibitics ???
I noticed on an earlier post that another doctos mentioned I could get to
11 Jul 2012, 03:09
I came in contact with a caterpillar of some sort about 4 years ago and I
still have the patch of little red dots it left me which covers an area of
skin about an inch in diameter. I was doing yard work in my back yard when
I felt a pinch on my lower stomach. I looked down and saw a fuzzy exotic
looking caterpillar crawling on my stomach. After I flicked off the
caterpillar, I saw it left a bunch of tiny hairs on my skin so I got tape
and tried to get it off but I guess I missed some. I cant believe after 4
years the scars are still there.
16 Jul 2012, 17:59
I got bit/stung with something on my upper thigh approx. 2 weeks ago while
I was gardening at first I thought mosquito but when I looked at my thigh
it was a 2 inch oval rash of small bumps so my next thought was red
ants-later I got a big red welt on my leg above-I have taken a few
Epsom-salt baths that helped the soreness then I found this site so at
least I know now for sure what bit me and what this rash is-it don't hurt
so much anymore but still there even after 2 weeks.
Chris in Iowa
01 Sep 2012, 13:39
My daughter is 8 yrs old and last Saturday she got stung by a puss moth
catepillar we found it on my nephews shirt. She is having horrible pain
in her lymphnodes through her whole body! The ER doctor knew nothing about
treating her. Sent us home and she has progressively gotten worse!!!
Yesterday our regular doctor tried to blow me off I insisted so he did
blood work but we won't have the results back till next Tuesday!! She is
getting paler, last night she had an episode with her stomach hurting
really badly! Today she is haing pains through her whole body again! From
her head to her knees!!! I am so scared does anyone have any information
on what can be done to help her??? The local doctors here know nothing!
02 Sep 2012, 22:55
Thanks for the info! I had no idea that caterpillars could cause a stingy
rash! Until I felt it today! I tried tea tree oil on the rash before I
read this site. The tea tree oil seems to have helped relieve some of the
sting! Thought that might be helpful info to add!
05 Oct 2012, 11:21
My little sister likes playing with all kinds of bugs and theres woolly
bear caterpillars all over and ive looked up if they're poisonous and some
say yes some say no. im so confused are they poisonous
Ask the Exterminator
05 Oct 2012, 11:30
It depends upon the caterpillar. Some caterpillars have hairs that irritate
human skin causing anything from a minor to severe rash.
24 Oct 2012, 20:04
Three days ago I had a "feathery" caterpillar down the back of my shirt for
3-4 hours while I was sitting on my couch, walking around my house, doing
laundry, etc. I kept feeling a prickly itchy feeling on my back, I'd
scratch at it through my shirt. I finally reached the back of my shirt
where the tag is at the neck and grabbed what I thought was some sort of
lint ball. It was a curled up caterpillar! My entire back is now COVERED
with a severe rash - I thought I had shingles again! The rash looks like
shingles, I feel bad just like when I've had shingles - only it's not on
one side of my body. I have spots on both arms, legs, stomach, under my
arms, the back of my neck. I have an appt with my dr in the morning. I'm
severely allergic to most insect bites, have developed shingles as a result
of them. Now I know exactly what I have! Thank you so much for this
site!!!!! I found a picture of the caterpillar on line. Will take it to my
doctor. I feel bad all over, feverish, achy, "nerve pain" just like I get
with shingles. It's bad but at least I know exactly what caused it!!!!!!
03 Nov 2012, 17:32
im nine years old and i was playing with a green caterpillar.it landed on
my hand.i screamed and it started gushing out green stuff.i thought it was
poison.then i screamed louder.i flicked it off luckly im okay.but this
webpage really helped.thank u.now i swear i will never touch a caterpillar
again.igot red of that green caterpiller.
23 Feb 2013, 01:11
Hi i also got bit by a wooly bear here down south texas and man did it
sting me..felt it all the way to my hip..burning and itching was crazy went
to doctor and told me to take aleve since im allergic to benadryl..Its been
day 3 and its still stinging slightly burning..My question is how long is
this going to take cause the heat here is not making it any better! Thank
you and this was the BEST INFO/BLOG!!!!!
11 May 2013, 20:44
Hi , im from singapore , i was walking out of my school to the nearest bus
stop , when i felt a crawling , ticklish feeling on my neck . I used my
hand to pick brush it off and realise it was a green yellowish caterpillar
with blue head . Right after that i felt a stinging sensation on the left
side of my neck . I didn't know what to do . So i just wash it with water
and thought it would be ok . But thn when i got home , it become super bad
. Rashes was all over my left side of the neck and it was itchy and pain .
I quickly ask my mum to apply vinegar on it to ease the itchiness . Im glad
i read this article , but i guess its abit late because i didn't know that
caterpillar leaves poisonous spines and hair , i am still having rashes and
swelling . I hope it will get better . What else can i do to to reduce the
14 May 2013, 01:21
I was trying to retrieve my cat that had got outside. I was holding on to
the rail of the stairs outside. The cat ran but I came in with a stinging
hand. Washed the area and packed on some baking soda paste. Also took a
I went out and looked to see if was a spider and instead I see a spiny
black and white caterpillar staring back at me. It stung like crazy for an
almost an hour until the antihistamine kicked in.
13 Jun 2013, 11:08
Hi I am an idiot. I was talked into eating a caterpillar. It had a pretty
close resemblance to the wooly bear.it was black and fuzzy with orange
stripes running down its sides.luckily the hair made me gag it out and I
didn't swallow it. The hairs had embedded into my tongue and random places
in my mouth.now I have sores all over my mouth.most of the hair is gone.
There are still a few there though. The pain in my mouth is almost
unbearable.it has been two days now and it is still bad. Is there any
remedy you know of that can help my mouth. I had no idea this hurt me this
bad. I know I am a dummy and have definitely learned my lesson. I will
never eat another bug again.
16 Jul 2013, 09:32
i am from Nepal. It was fine the day before, but the next day when i woke
up, there were rashes all over my body especially the right side of my
body.It was so irritating and painful.Well, i suspect there was a
caterpillar on my bed or maybe some hair of the caterpillar.
It's actually a bad experience. Take care people, and clean your bed before
you sleep. Thats my little piece of advice.So long!
02 Aug 2013, 20:28
I got stung by a Saddleback Caterpillar about an hour ago on my index
finger. I googled so many pages and finally found the distinct picture.
Besides the extreme needle like pain in my finger and a little swollen,
Will I look forward to any other reaction. Icing it and took a benadryl. Is
it poisonous? Sigh. Thanks, Exterminator.
10 Aug 2013, 21:37
About three days ago, someone accidentally threw a caterpillar at me! It
was white-cream and VERY furry, with a few orange horns on it's front/head
area. I am not sure exactly what happened but the next thing I knew, there
were a bunch of small/medium welts on my thigh which are extremely itchy.
After that I scratched other areas of my body which also broke out in
welts. I have been taking kid's allergy relief and applying anti-itch
cream. Thanks. If you know about this caterpillar or have had a similar
experience please respond.
13 Sep 2013, 20:47
I have horses and huskies, besides working outside I have to treat the
animals for bites, scrapes and bumps. There's two things I always keep on
hand that have really helped 1. is Bentonite Clay (I use California Earth
Minerals - human grade), the 2nd is Olive Leaf - I buy bulk leaf and grind
it in the coffee grinder and keep it in a mason jar. For bites, scrapes,
etc. I mix equal parts with a little distilled water (drinking water) to
make a little paste - then apply generously to the area and surrounding
area. It will feel cool on the skin. The clay may help draw out the toxin
- but you can research everything about what I have mentioned. One of my
dogs got a hold of some Nandina berries - toxic and he was very sick. I
put about 1/2 teaspoon of the clay in warm milk and he drank it - he made
it through the night. So, research - if you do yard work or play out in
the elements, there are things you might want to keep on hand for
emergencies. I hope what I wrote helps. The clay by the way when taken
internally also helps remove toxins from the body - from what I have read.
15 Sep 2013, 12:30
Lessie Richard, is your daughter recovered ?
15 Sep 2013, 18:54
Two days ago... I was camping and noticed an itching sensation at the neck
of my shirt. It was nighttime and when I touched the caterpillar I threw
it off me. The next day I had itching and felt a stinging sensation at the
Today I have a severe red rash around my neck and chest area. Am treating
with Claritin and Hydrocortisone cream. It looks very "red" and continues
to spread. May need to go to the doctor tomorrow. No breathing
difficulties, but feel somewhat feverish.
23 Sep 2013, 00:39
I was stung while at the river. I believe this was one of the worst pains
ever! Knew nothing about catepillars until i researched the mark. Ice and a
paste of water and baking soda was my only relief. Its been a month and it
is still scabbed and raised and swollen some days but is going away. Hope
this helps someone else.
14 Oct 2013, 10:15
We were sitting under a Sycamore Tree here in Lexington SC. There must have
been a nest of white, furry, horned caterpillars everywhere. Two got under
my shirt and I felt the worst stings. They say they don't sting but I am
living proof that oh yes they do! I immediately felt a burning sensation at
the site. I cleaned the area but within hours I was covered in a red rash,
welts, severe itching that spread over my torso, back, left arm, hand and
my feet felt like I was walking on hot coals. I ended up in an urgent care
center where I was given a shot of Solumedrol and given a script for
steroids. I am feeling better this a.m. as the shot is kicking in.
04 Nov 2013, 17:32
Mercy I just came from the doctor an was shocked to be told I was bit by a
caterpillar on my neck.. my neck had a large quarter size knot with a black
dot in the middle.. it stinks an itches.. causing me to shake as if im
freezing, along with my blood pressure going sky high an fever.. thank GOD
I was able to get in to see the doctor an get a shot an some antibotics...
I had no clue caterpillers would even hurt you.. this is a great site with
good informatiom... thank you all kindly for the info...