What Does a Caterpillar Rash Look Like?

Contact with the venomous or irritating hairs include symptoms of extreme itch followed by wheals and a variable rash which can include a burning sensation. Other symptoms are dermatitis, pain, itching, and swelling of the affected area.

Medical Entomology staff can identify the moths or caterpillars and offer advice on control and avoidance. When handling these insects, suitable protective clothing such as eyewear and gloves should always be worn.

If the caterpillar infestations are causing an appreciable problem, a pest control officer can chemically treat the food plant or harbourage area. The best remedy is to recognise the food plants and avoid them at their active growing period.

How long does caterpillar rash last?

These symptoms appear within minutes or hours after contact and last anywhere from one to several days. Contact with mucous membranes (for example, a child putting a caterpillar in their mouth) can cause more serious reactions such as shortness of breath, conjunctivitis, difficulty swallowing, and hay fever.

How do you treat caterpillar rash?

Apply an ice pack to reduce swelling and pain. Create a paste using baking soda and water and slather it on the affected skin to reduce itching. A hydrocortisone cream also may be used. Take an oral antihistamine (such as Benadryl®) if the reaction to the sting worsens.

What are the symptoms of a caterpillar sting?

Symptoms occur when the setae or spines contact human skin. Pain, itching, and a rash are common. Blistering and swelling are possible. If setae blow into the eyes, eye irritation is expected.

Are caterpillar rashes contagious?

The rash itself is not contagious. It’s caused by a reaction to the toxins that are in the hairs.

Kids’ Health Kids’ Skin Health What Parents Should Know About Caterpillars By Vincent Iannelli, MD Vincent Iannelli, MD Facebook Vincent Iannelli, MD, is a board-certified pediatrician and fellow of the American Academy of Pediatrics. Dr. Iannelli has cared for children for more than 20 years. Learn about our editorial process Updated on October 22, 2021 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. Medical Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Corinne Savides Happel, MD Medically reviewed by Corinne Savides Happel, MD LinkedIn Corinne Savides Happel, MD, is a board-certified allergist and immunologist with a focus on allergic skin disorders, asthma, and other immune disorders. Learn about our Medical Review Board Print Table of Contents View All Table of Contents Causes and Symptoms Misdiagnoses Treatment Of all the bugs and insects kids come into contact with, caterpillars seem pretty harmless. After all, these fuzzy little creatures are kind of cute, and, eventually, they turn into butterflies or moths. While its true that an encounter with a caterpillar isn’t as potentially dangerous as, say, a bee sting or a tick bite, caterpillars aren’t always as innocent as they look. So, while children may find it fun to pick up and play with a caterpillar, they could be inviting an itchy and even painful rash. Verywell / Brianna Gilmartin Causes and Symptoms The caterpillar characteristic that’s usually most temptingthe fuzzy tufts that make them seem like the cuddly stuffed toys of the insect worldis the one that can cause trouble. It is thought that exposure to the creature’s tiny hairs, called setae, triggers an overactive immune response in some people. Reacting to what it perceives to be a threat, the immune system will flood the body with a pro-inflammatory compound called histamine. This can incite an array of allergic symptoms involving the skin, eyes, and respiratory tract. Touching a caterpillar can cause redness, swelling, itching, rash, welts, and small, fluid-filled sacs called vesicles. There may also be a burning or stinging sensation. Other species of caterpillar, like the southern flannel moth (Megalopyge opercularis) indigenous to parts of Texas, are known to inflict stings and trigger a localized skin reaction. See the photo below for an example of what symptoms of a rash caused by a caterpillar may look like on a human arm. This photo contains content that some people may find graphic or disturbing. See Photo Caterpillar rash. iStock / Getty Images Plus These symptoms can appear within minutes and last for one or more days. If a child touches their eyes or nose after handling a caterpillar or places one in their mouth, there could be a more serious reaction. There may be sneezing, coughing, runny nose, red eyes, shortness of breath, mouth pain, itching, and difficulty swallowing. Common Allergic Reactions After Insect Bites and Stings Misdiagnoses What makes reactions to caterpillars most confounding is that they can easily be mistaken for something else and therefore not treated properly. In 2011, 23 children in Florida developed rashes from exposure to white-marked tussock moth (Orgyia leucostigma) caterpillars. According to the report issued by the Centers for Disease Control and Prevention (CDC), most of the kids were initially misdiagnosed with a variety of conditions, including chickenpox, molluscum contagiosum, and even potentially life-threatening MRSA infections. In other cases, rashes caused by caterpillars have been mistaken for flea bites, mosquito bites, scabies, scarlet fever, fifth disease (parvovirus B19), and contact dermatitis. It’s important to know that sometimes a child can get a rash without actually putting his fingers on a caterpillar, especially in areas where there are a lot of the critters at once. The little tufts can become airborne and land on bare skin. They also can leave setae behind on items kids commonly come in direct contact with. One of the recommendations by the CDC in response to the Florida outbreak was to advise schools and daycare centers where caterpillars are common to power wash playground equipment to remove the caterpillars. Treatment If your child develops a rash after an encounter with a caterpillar, it usually won’t be serious and can be treated at home. If the reaction is immediate and mild, you will first need to remove as many of the tiny hairs that have rubbed off onto the skin. To do this, simply rub a strip of tape across the affected skin as you would with a lint roller. Repeat with fresh pieces of tape until you’ve gotten out all of the hair that you can. Afterward, wash the skin with soap and water and dab on a low-potency steroid cream. If the rash really stings, the 10- to 15-minute ice application can usually help relieve the pain. On the other hand, if there is extreme swelling with or without respiratory symptoms, it is best to play it safe and either call your pediatrician or go to your nearest urgent care center. Though thought to be extremely rare, anaphylaxis can be seen after exposure to certain caterpillars in predisposed individuals. In a case published in 2014, boy developed hives and shortness of breath after exposure to a spotted tussock moth (Lophocampa maculata) caterpillar. When to See a Doctor About a Skin Rash Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You’re in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 4 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Rahlenbeck S, Utikal J. The oak processionary moth: a new health hazard?. Br J Gen Pract. 2015;65(637):435-6. doi:10.3399/bjgp15X686341 Forrester MB. Megalopyge opercularis caterpillar stings reported to Texas poison centers. Wilderness Environ Med. 2018;29(2):215-20. doi:10.1016/j.wem.2018.02.002 Centers for Disease Control and Prevention. Caterpillar-associated rashes in children Hillsborough County, Florida 2011. MMWR. 2012 Mar 30;61(12);209-11. Dugar B, Sterbank J, Tcheurekdjian H, Hostoffer R. Beware of the caterpillar: anaphylaxis to the spotted tussock moth caterpillar, Lophocampa maculata. Allergy Rhinol (Providence). 2014;5(2):113-5. doi:10.2500/ar.2014.5.0086

Moths and butterflies, and their larvae, caterpillars, belong to the order Lepidoptera. Although there are an estimated 125,000 to 150,000 different species in this order, very few are capable of causing adverse reactions in humans. Caterpillars are responsible for the vast majority of adverse reactions. Adult moths are less commonly implicated, and adult butterflies do not appear to be responsible for any adverse reactions in humans.

Occasionally the irritating hairs can be detached and dispersed by winds, causing large outbreaks of reactions in humans. These hairs may also surround cocoons, eggs (transferred from the abdomen of female moths), or other environmental objects.

In very rare cases, spurs on the legs of large moths can penetrate human skin and cause stings, dermatitis , or urticaria . Rare species of moths, from the genus Calyptra, are able to bite human skin in order to feed on blood. Worldwide it is difficult to quantify the number of people affected, as many of the reactions are mild and are not reported to health authorities.

Some species of Lepidoptera become prolific in summer leading to epidemics of adverse reactions, for example summertime outbreaks of dermatitis from gypsy moth caterpillars in parts of the United States. Severe pain occurs in all patients, and 1 in 3 develop systemic reactions such as headache, muscle spasms, breathing difficulty, and convulsions . Reactions range from mildly itchy, papular urticaria (small red bumps and swelling) that resolves within an hour; to moderately itchy, urticarial , scaly , blistering, or widespread eczema –like reactions that can persist for weeks.

Over the next few days widespread bleeding occurs into the skin, mucous membranes, lungs, brain, or kidneys. Biting moths Symptoms have been described as painless and transient to intensely painful with swelling that persists for up to 24 hours. Biting moths, from the genus Calyptra, are found only in southern and Southeast Asia and eastern Russia.

Dendrolimiasis and pararamose These refer to itchy skin rashes associated with joint pain or inflammation . The clinical features are non-specific and mimic those of many other insect bites , allergic reactions, and dermatological conditions. Stinging reactions may be relieved with the application of ice, oral pain relief such as paracetamol, or topical anaesthetics.

Eczematous reactions can be treated with topical steroids or oral antihistamines , but these treatments are not always effective.


Symptoms from stinging caterpillars usually include instant pain, with a longer lasting ache and a raised weal that usually soon subsides.Contact with the venomous or irritating hairs include symptoms of extreme itch followed by wheals and a variable rash which can include a burning sensation. Other symptoms are dermatitis, pain, itching, and swelling of the affected area.The intensity of the irritation is dependent on the sensitivity of the patient and the species of caterpillar.Detached hairs if inhaled may cause laboured breathing. Irritation in some cases can last for days. Eye injuries have also been reported and may lead to conjunctivitis.


A recent history of contact with a moth, caterpillar or food plants are usually required to determine if and which caterpillar has caused a problem. Identification of the caterpillar or moth with pictures or taxonomic keys is essential in the prevention and control of stinging and itchy caterpillar infestations.Medical Entomology staff can identify the moths or caterpillars and offer advice on control and avoidance.