Saddleback Caterpillar Sting: Quick Relief and Prevention Tips

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The saddleback caterpillar is a fascinating creature, known for its unique appearance, featuring a distinct green and brown pattern. Its back displays an oval-shaped, purplish-brown spot surrounded by a green patch, which gives the caterpillar its “saddleback” name. While this intriguing insect may catch your eye, it’s essential to be cautious around it due to its sting.

These caterpillars possess venomous spines on their body, which can deliver a painful sting when touched. The pain level and severity of the sting can vary depending on factors such as contact time, caterpillar size, and your sensitivity to the venom. It’s important to be aware of the saddleback caterpillar’s presence, particularly when exploring outdoors, as the sting can be as painful as a bee sting.

By understanding the saddleback caterpillar’s distinguishing features and being informed about its sting, you can better protect yourself and appreciate the beauty of this unique insect. Just remember to admire from a safe distance and be mindful of your surroundings to avoid any unwanted encounters.


Physical Characteristics

Saddleback caterpillars, scientifically known as Acharia stimulea, are easily recognizable by their distinct appearance. These creatures have a bright green body adorned with a brown, oval spot at their center, resembling a saddle. They also have venomous spines on their body, which can cause painful stings if touched.

Their adult moth stage, known as a limacodid or flannel moth, has a dark brown color with small white and cinnamon spots. The larva, commonly called slug caterpillars, have a unique movement style and sticky “suckers” that help them grip and move between leaves.

Habitat and Distribution

Saddleback caterpillars are commonly found in Eastern North America and can inhabit various environments such as trees, gardens, and even corn fields. They primarily feed on a variety of host plants like:

  • Oak
  • Spicebush
  • Basswood
  • Chestnut
  • Cherry
  • Plum
  • Ornamental plants

These caterpillars are often spotted on the upper surface of leaves or attaching themselves to a stick when they’re ready to form a cocoon. Be cautious while gardening or working around trees where these vibrant, yet venomous caterpillars might be hiding.

Remember, when in doubt, it’s always better to observe these fascinating creatures from a safe distance to avoid any unpleasant encounters. Happy exploring!

Life Cycle

Eggs and Larvae

Saddleback caterpillars start their life as eggs laid on host plants. These eggs hatch into small green larvae called first instar, which grow through a series of stages called instars. The larvae feed on leaves and turn into medium orangish worms with yellow stripes. In their final stage, they become large, black- and yellow-striped caterpillars with black heads and reddish prolegs.

Stage Characteristics
1st Instar Small green larvae
2nd Instar Medium orangish worms with yellow stripes
Final Instar Large black- and yellow-striped caterpillars


Upon reaching maturity, saddleback caterpillars spin a tough silk cocoon to protect themselves during the pupal stage. They undergo metamorphosis and transform into adult moths within this cocoon. The adult moths are fuzzy and dark brown in color.


Saddleback caterpillars face a variety of predators during their life cycle. While in the larval stage, they can fall prey to birds, parasitic wasps, and other predators that attack caterpillars. The tough silk cocoon helps protect the pupae, but some predators may still manage to break through.

In summary, the life cycle of saddleback caterpillars starts with eggs laid on host plants which hatch into larvae. The larvae go through several instars, each with unique characteristics, and eventually spin a cocoon for protection. Adult moths emerge from the cocoon and face a range of predators throughout their lives.

Sting Mechanism

Poisonous Spines

Saddleback caterpillars have venomous spines on their body, which they use for self-defense. These spines contain a toxin that can cause intense pain and various symptoms in humans. When you accidentally touch or brush against a saddleback caterpillar, the spines break off and release the venom into your skin, causing a sting-like sensation.

Physical Interaction

It’s essential to be aware of the saddleback caterpillar’s habitat and take the necessary precautions when working around them. For example:

  • Wear long-sleeve shirts
  • Use gloves, preferably leather gloves, to minimize skin contact

By taking these precautions, you can reduce the chance of experiencing a painful sting and its side effects.

Response in Humans

A saddleback caterpillar sting can cause various symptoms in humans, ranging from mild to severe. Common reactions include:

  • Pain, similar to a bee sting
  • Burning sensation at the site of contact
  • Redness
  • Swelling
  • Itching
  • Rash
  • Nausea
  • Headache

In some cases, an allergic reaction may occur, resulting in more severe symptoms, such as hemorrhaging. If you experience an intense reaction to a saddleback caterpillar sting, it’s essential to seek medical attention promptly.

To alleviate pain and itching, try using adhesive tape to remove any remaining spines from your skin. Keep the affected area clean and consider over-the-counter remedies to manage symptoms. Always consult with your doctor for appropriate treatment options, especially in cases of severe pain or an allergic reaction.

Treatment and Prevention

Immediate Action

If you get stung by a saddleback caterpillar, take these steps:

  1. Gently remove the spines using a stick or adhesive tape.
  2. Wash the area with soap and water.
  3. Apply a cold compress, like an ice pack, to reduce pain and swelling.

You may also want to use a baking soda paste to help soothe the sting site. To make this paste, mix equal parts baking soda and water, then apply it to the affected area.

Medical Intervention

In case of severe reactions or if symptoms persist, it’s wise to seek medical attention. A healthcare professional may recommend treatments such as:

  • Over-the-counter hydrocortisone cream to reduce itching and inflammation.
  • Oral antihistamines to help alleviate allergic reactions.

However, it’s essential to consult a physician for severe symptoms, as delayed or improper treatment can lead to complications. Remember, complications from saddleback caterpillar stings are generally rare and not fatal.

Preventive Measures

To avoid stings from saddleback caterpillars, you can adopt these precautions:

  • Wear gloves, preferably leather, when handling foliage.
  • Use a long-sleeve shirt to protect your arms while working outdoors.
  • Regularly inspect trees and plants for caterpillar presence and take control measures as needed.

While handpicking caterpillars can be effective, ensure you wear gloves to protect yourself from stings. By taking these precautions, you can minimize your risk of encountering saddleback caterpillars and the discomfort their stings can cause.

Interesting Facts

Saddleback caterpillars are an intriguing species in the slug caterpillar family. Found in various regions, they are known for their unique appearance and stinging hairs. Here are some fun facts you might not know about these fascinating creatures.

The saddleback caterpillar boasts a distinctive green blanket-like pattern on its back. This vibrant coloration isn’t just for show – it serves as a warning to predators of its potentially painful sting. Beneath this green blanket, the caterpillar sports a brown body adorned with menacing spines.

These spines are no joke. When touched, saddleback caterpillars can deliver a painful sting that might cause symptoms such as:

  • Swelling
  • Nausea
  • Itching
  • Redness

You’ll find that the saddleback caterpillar is merely a stage in the life cycle of its adult form, the moth. The Acharia stimulea moth is a glossy, dark brown, and quite furry creature with a single white dot near the forewing base. Its wing span ranges from 26-43 mm.

Despite the potential harm saddleback caterpillars could cause, it’s important to remember that they play a vital role in the ecosystem. So, while you should be cautious of their stinging hairs, also appreciate the captivating beauty and role they occupy within our natural world.

Reader Emails

Over the years, our website, has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Saddleback Heterocampa


What is this caterpillar?
I emailed earlier this month and not long after your site went down for a while so I don’t know if it went through. We found the caterpillar wandering on the ground and although he resembles the Heterocampa that someone sent from MO, ours is quite a shocking shade of hot pink. We are in Hempstead, TX. in the middle of the Post Oak belt. The caterpillar has formed a chrysalis and we will wait and see if it transforms. But I would really like to know what we are looking for.
Thanks in advance,
Joy Sebastian-Hall

Hi Joy,
Yes, you have a caterpillar from the genus Heterocampa. Somewhere I remember reading that they change color just before pupating. There is much color variation in the green, brown and pink range. The moths are a grey color.

Letter 2 – Saddleback Caterpillar Moth


Subject: Who dat?
Location: Reston va
June 19, 2014 1:04 pm
My son found this odd critter on our screen. Location- Reston va
Signature: Buggin

Saddleback Caterpillar Moth
Saddleback Caterpillar Moth

Hi Buggin,
We spent many vacations in the late 1960s and early 1970s in Reston because our uncle was one of the first contractors to begin building in the model town, but we haven’t seen it since 1980, and we expect much has changed.  This is a Saddleback Caterpillar Moth as you can see from this matching image on BugGuide.  Though we have not shortage of stinging Saddleback Caterpillar images, this is the first we have posted of the adult moth.

Letter 3 – Saddleback Caterpillar stings husband in New Jersey


Subject:  Rare Insect
Geographic location of the bug:  Southern New Jersey
Date: 08/08/2019
Time: 07:26 PM EDT
Your letter to the bugman:  This weird/rare looking insect is eating the leaves on our Asian pear tree & when my husband pulled one off a leaf it stung him & left his skin feeling temporarily numb.
How you want your letter signed:  Sharon Beningo

Saddleback Caterpillar

Dear Sharon,
The Saddleback Caterpillar,
Acharia stimulea, is not considered rare, and BugGuide reports sightings in much of eastern North America.  The stinging capability of the Saddleback Caterpillar is well documented, including on Featured Creatures where it states:  “Color patterns are aposematic, or having bright warning colors that denote toxicity or distastefulness” and “The large spines and potent hemolytic venom rank it as one of the most important North American species of urticating caterpillars.”

Thanks so much for your quick response. We will definitely not be touching any more of them!

Letter 4 – Saddleback Caterpillars


Dear bugman,
We found four of these bugs in Southern New Jersey on August 13 on a Burning Bush (it was not actually on fire, thats the name of the bush)! Whats that bug? Please reply if it is not too much trouble!
Josh Gager & Lindsey Williams

Hi Josh and Lindsey
These are Saddleback Caterpillars, Sibine stimulea. Handle with care since those are stinging spines that will cause local irritation, but no lasting effects.

Letter 5 – Saddleback Caterpillars from Guatemala


Subject: My Grandfather infestation
Location: Guatemala, Villa Nueva
October 11, 2015 4:07 pm
Hi ,
I am currently staying in Guatemala while i was trimming roses something fell on me. At first glance i thought it was a spore but once I felt pain and a slight burning sensation I realized I was wrong. I found so many of these critters varying in sizes and they are always in groups . I just want to know if they are safe for my grandfather’s garden.
Signature: Crystal

Saddleback Caterpillars
Saddleback Caterpillars

Dear Crystal,
These are either Saddleback Caterpillars,
Acharia stimulea, which according to BugGuide ranges from “Massachusetts south to Florida and west to eastern Missouri and Texas,” or another member of the genus that ranges further South.  As you noted, they are capable of stinging, and according to BugGuide:  “Caterpillars are capable of inflicting lasting and painful stings with their spines,” however, the sting is not considered dangerous.  We suspect your grandfather is already aware of these Saddleback Caterpillars and their stinging potential.

Saddleback Caterpillars
Saddleback Caterpillars

Letter 6 – Saddled Prominent


We found this caterpillar crawling on my husband’s shirt. I placed him on a hibiscus for his photo shoot. We live in south Louisiana. Thanks.
Marcie Melancon

Hi Marcie,
This is one of the Prominent Moth Caterpillars in the genus Heterocampa, probably the Saddled Prominent, Heterocampa guttivitta.

Letter 7 – Saddled Prominent Caterpillar


Caterpillar on Persimmon
Attached are two photos of a caterpillar that I found on my native persimmon tree here in eastern Pennsylvania. These pics were taken this morning, 15 July 2007. The caterpillar is about 1.5 inches long. Do you know what this is? Thanks,
Rick Stuby

Hi Rick,
We believe this to be a Saddled Prominent Caterpillar, Heterocampa guttivitta, as pictured on BugGuide.

Mr. Marlos,
Thank you for the very quick reply! I looked on Bugguide (thanks for that reference, too) at the Heterocampa guttivitta and other photos from the genus. I see a number of similarities, but I do not think that what I “have” is guttivitta. The head on mine is black, not green and there are no dark markings on the dorsal line of mine. I have attached another photo which may show that better. There is a small green-yellow X-shaped saddle on it. If you have any other ideas, please let me know. In any case, I appreciate your time and effort! Kind regards,
Rick Stuby

Caterpillars are often variable. Try these links

Thank you yet again, Mr. Marlos. I guess that it could be guttivitta. I’m tempted to put it in a jar and find out, but I don’t think I have the patience or the ability to distinguish subtle differences that are no doubt in the adults as well! I really appreciate your interest and your resources. God bless,
Rick Stuby

Letter 8 – Stung by Saddleback Caterpillar


Unfortunate meeting with a saddleback caterpillar
Location: Central NJ
August 7, 2011 7:32 pm
I was weeding today and reached around a blue mist shrub and felt a sting in my forearm and found one of these saddlebacks. I only brushed it and the stinging lasted for a couple of hours. Went back to the plant and found 1 more.
Signature: malbug

Stinging Saddleback Caterpillar

Dear malbug,
Though we frequently get identification requests for Saddleback Caterpillars, it is not as frequent that we get a report that someone has been stung.  Saddleback Caterpillars are not aggressive, and they do not actively seek out folks to sting, however, situations like yours are the most frequently reported stinging encounters.  People will often accidentally brush against Saddleback Caterpillar or other stinging species with startlingly painful results.  Other North American stinging caterpillar species include the Asp or Puss Caterpillar, the Monkey Slug, the Tussock Moth Caterpillar, the Buck Moth Caterpillar, and the Io Moth Caterpillar.  You might also be interested in this University of Kentucky Entomology page on Stinging Caterpillars

Letter 9 – Unknown Saddleback Caterpillar


Whats this bug
I found this bug at our house in a tree. It stung my dad. Can you please tell us what it is? Thanks
Nicholas and emma!!
Mark Berryman

Hi Nicholas, Emma and Mark,
This is a Saddleback Caterpillar. Information can commonly be found on websites that are devoted to stinging caterpillars. The markings are quite different from Sibine stimulea, a common species, but we believe it is the same genus. The newest information indicates that the genus has been reclassified as Acharia. In the event that this genus is incorrect, this is a Stinging Slug Moth Caterpillar in the family Limacodidae. You did not provide a location, so we don’t know where this was found.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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7 Comments. Leave new

  • Great info site! My husband leaned back in a chair outside this morning and was stung by a saddleback. We put it in a bug jug…didn’t know what it was. He said the sting was worse than a wasp! Thanks for this site–we know what it is now and will avoid it like the plague. It’s alive and I’m turning it loose far from the house!

    • Thanks for sending your personal account as a comment. Some people might have severe allergic reactions since modern medical science seems to be revealing more and more allergies to an ever increasing number of things in select individuals.

  • I was trimming some shrubs and got stung in my finger. Hurts a lot and felt a numbing affect at the end of my finger. Poured some Ammonia on it and then washed my hand thoroughly. Found this bug and did not know what it was. NEVER saw one of these before. The sting was 30 minutes ago and it still hurts.

  • My 34 year old daughter just got stung by one on my front porch. Set her hand down on it on the porch rail without looking . She is allergic to wasp and bee stings so we are waiting to see if she has any reaction. Prepared to head to doctor if needed. I am 69 years old, always outside and have never seen one of these.

  • Got stung by 2 at once a few moments ago when my shoulder brushed against an oak leaf. Needless to say, I never want to get stung again. Hot needle sensation. PAINFUL! My wife got stung 2 years ago. Now I know why she pitched such a fit.

  • I found two tiny pink caterpillars in our bed… yulk!!!
    but now i’m reading they could be some sort of cotton moth? we do have cotton sheets! …but also i read that some can turn pink before pubation.
    We live in Alicante Spain for 20 years and i have never seen this before.

  • I found two tiny pink caterpillars in our bed… yulk!!!
    but now i’m reading they could be some sort of cotton moth? we do have cotton sheets! …but also i read that some can turn pink before pubation.
    We live in Alicante Spain for 20 years and i have never seen this before.


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