Do Underwing Caterpillars Bite? A Friendly Guide to Their Behavior

Underwing caterpillars are often a topic of curiosity, particularly when it comes to whether or not they bite. These intriguing creatures are the larval stage of underwing moths, known for their striking wing patterns and colors.

It’s important to note that underwing caterpillars, like other caterpillars, do not have the ability to bite or sting humans. Instead, they primarily rely on their chewing mouthparts for consuming plant material – leaves, to be more specific. So, there is no need to be concerned about the possibility of getting bitten by these interesting insects.

However, some other caterpillar species possess stinging hairs (urticating hairs), which can cause discomfort to humans when they come in contact with them. These barbed hairs can break off and embed in a person’s skin, causing pain and irritation. So, it’s wise to exercise caution while handling or encountering any unfamiliar caterpillar species.

Profile of Underwing Caterpillars

Caterpillar Species

Underwing caterpillars belong to the moth family Noctuidae, specifically the genus Catocala. They are the larval stage of Underwing moths which are common in North America, inhabiting forests, shrublands, and sometimes gardens.


To identify Underwing caterpillars, some key features include:

  • Prolegs with crochets (hook-like hairs)
  • Tubercles with setae (hair-like structures)
  • Dorsal hump on some species
  • Presence of spiracles on the sides


Underwing caterpillar sizes may vary from around 5 cm to 7 cm in length depending on the species and age of the larva.

Coloration and Camouflage

Underwing caterpillars exhibit incredible coloration involved in their camouflage. They are often found on trees like oak, hickory, and apple, where they blend in with the branches and foliage. The primary color patterns of Underwing caterpillars can range from brown to green, with additional markings or stripes.

Comparison Table

Feature Underwing Caterpillars Tent Caterpillars
Family Noctuidae Lasiocampidae
Genus Catocala Malacosoma
Habitat Forests, shrublands, gardens Trees in forests, urban areas
Size 5 cm – 7 cm Around 5 cm
Camouflage & Coloration Brown or green, with markings or stripes Distinct blue-black color, white stripe on the back

Underwing caterpillars are not known to be venomous or have stinging hairs. They feed on leaves of various trees and shrubs, usually at night to avoid predators during the daytime. However, their impressive camouflage is their first line of defense against potential threats.

Habitat and Range

North America

Underwing caterpillars are commonly found in deciduous forests across North America, particularly in states like Texas, Minnesota, Arkansas, and Maine. These caterpillars thrive in areas with:

  • Maple trees
  • Birch trees
  • Rose plants


In Europe, underwing caterpillars inhabit various ecosystems, including forests and grasslands, where they feed on a variety of plants.


Underwing caterpillars also have a presence in Eurasia, where they can be found in similar habitats as in Europe.

Comparison Table

Region Main Habitats Common Host Plants
North America Deciduous forests Maple, Birch, Rose
Europe Forests, Grasslands Various
Eurasia Similar to Europe Similar to Europe

In conclusion, underwing caterpillars inhabit different ecosystems across North America, Europe, and Eurasia, typically in wooded areas with a variety of plant species.

Do Underwing Caterpillars Bite?


Underwing caterpillars primarily possess mouthparts designed for chewing on leaves. They have mandibles, which allow them to effectively cut their host plants for feeding. However, their mouthparts are not intended for biting humans or animals.

Venomous or Poisonous?

Underwing caterpillars are neither venomous nor poisonous. They don’t contain any toxins that could harm humans or animals upon contact or ingestion. However, there are other caterpillars, such as stinging caterpillars, that do possess venomous hairs, which can cause skin irritation or rash when touched.

Biting vs. Stinging

To clarify the difference between biting and stinging caterpillars:

  • Biting caterpillars do not exist since they use their mandibles for feeding on plants.

  • Stinging caterpillars sport urticating hairs that can cause skin irritation or rash upon contact. Examples include saddleback caterpillars and puss caterpillars.

For further understanding, refer to the comparison table below:

Caterpillar Type Bite Humans? Sting Humans?
Underwing No No
Stinging No Yes

In summary:

  • Underwing caterpillars do not bite or sting humans.
  • Keep in mind that other types of caterpillars, such as stinging caterpillars, can cause skin irritation if touched.
  • Always be cautious around unfamiliar insects in the environment.

Signs and Symptoms of Caterpillar Stings

Physical Symptoms

Caterpillar stings can cause various physical symptoms, which are usually caused by the toxin-containing hairs or setae present on certain caterpillars, like the saddleback and puss caterpillars. Common physical symptoms include:

  • Itching and rash: After being stung by a caterpillar, one may experience itching and develop a rash on the skin.
  • Pain and burning: Stings from these caterpillars may cause a painful, burning sensation.
  • Swelling: Some individuals may experience swelling around the sting area.
Symptom Description
Itching and rash Itchy skin and rash formation
Pain and burning Sensation of pain and burning at sting area
Swelling Inflammation around sting area

Allergic Reactions

In addition to the physical symptoms caused by the toxin in caterpillar hairs, some individuals may experience more severe allergic reactions. Example symptoms of an allergic reaction include:

  • Nausea: After being stung by a caterpillar, an individual may feel nauseous.
  • Increased swelling: In some cases, an allergic reaction can lead to more severe swelling, not just around the sting area.

Allergic reactions to caterpillar stings are not very common but may vary in severity among individuals.

Pros and cons of getting stung by a caterpillar:

  • Pros: None, as getting stung by a caterpillar is generally a negative experience.
  • Cons: Pain, itching, rashes, swelling, potential allergic reactions.

First Aid and Treatment

Immediate Management

If you suspect a bite from an underwing caterpillar, it’s essential to take immediate action. Start by:

  • Removing caterpillar hairs: Use tape to gently lift any visible hairs or spines from the skin.
  • Cleaning the area: Wash the affected skin with soap and water to reduce irritation and potential infection.

Home Remedies

For pain and itchiness relief, you can try the following home remedies:

  • Baking soda: Mix baking soda and water to create a paste, and apply it on the affected area.
  • Hydrocortisone cream: Apply a topical over-the-counter hydrocortisone cream to reduce inflammation and itching.
  • Antihistamine cream: Use an antihistamine cream to alleviate allergic reactions and discomfort.

Remember to:

  • Avoid scratching the affected area to prevent further irritation or infection.

Medical Help

For severe reactions, such as those from the saddleback caterpillar, seek immediate medical attention. Here’s a comparison table between common underwing caterpillars and the more dangerous saddleback caterpillar:

Characteristic Common Underwing Caterpillars Saddleback Caterpillar
Danger Level Mild irritation Potentially high: intense pain, swelling, nausea
Location Widespread in North America Predominantly in the Eastern U.S.
Appearance Mostly dull-colored with brightly colored hindwings Green, with a distinctive “saddle” pattern on the back

In conclusion, remain aware of different caterpillar species, and follow the appropriate first aid and treatment when dealing with their bites.

Preventing Caterpillar Problems

Gardening Tips

To prevent caterpillar problems, focus on implementing healthy gardening practices. For example:

  • Planting different types of grasses and seedlings to diversify the ecosystem
  • Regularly inspecting plants for early signs of caterpillar infestations
  • Incorporating natural predators, such as birds and beneficial insects, in the garden or woodland area
  • Planting resistant varieties, such as species less attractive to the underwing caterpillar (e.g., avoiding elm and cherry trees)

It’s worth noting that some caterpillars, like the io moth caterpillar, can be particularly harmful to certain plants. Identifying the specific species present can help tailor prevention measures.

Lights and Traps

Another effective method is using lights and traps to monitor and control caterpillar populations. Examples include:

  • Installing outdoor lights that do not attract moths and their larvae, like yellow sodium vapor bulbs
  • Using pheromone traps to capture male moths, helping reduce potential mating and reproduction

Comparison Table

Method Pros Cons
Healthy Gardening – Natural prevention method
– Promotes biodiversity
– May not be effective against all species
Lights and Traps – Can target specific species
– As a monitoring tool
– May require maintenance and monitoring

Remember that it’s essential to address caterpillar problems for a healthy garden, preventing damage to plants’ roots and foliage. By following these tips and using appropriate methods, gardeners can effectively protect their plantings from harm.

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.


  • 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.

    View all posts
  • 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.

    View all posts

Leave a Comment