Are Tussock Moth Caterpillars Poisonous? Uncovering the Truth

Tussock moth caterpillars are a common sight during summer months, often found on trees or foliage.

These caterpillars, with their distinctive tufts of hair, have piqued the curiosity of many regarding their potential toxicity.

While not exactly poisonous, some species of tussock moth caterpillars can cause skin irritation in sensitive individuals due to their hair-like bristles, called setae.

Are Tussock Moth Caterpillars Poisonous
Banded Tussock Moth Caterpillar

For example, the Hickory Tussock Moth Caterpillar is known for causing an itchy rash in some people upon contact.

Remember to exercise caution when handling these curious creatures, as reactions may vary from person to person.

It is always best to observe from a safe distance and avoid direct contact with tussock moth caterpillars.

Are Tussock Moth Caterpillars Poisonous?

Hickory Tussock Moth Caterpillar

Hickory tussock moth caterpillars are found in North America. They feed on various tree species, like hickory, oak, and maple.

One unique feature of these caterpillars is their white and black hairs, which can cause skin irritation in some individuals.

If touched, it’s best to wash your hands thoroughly to avoid any possible adverse reactions.

Spotted Tussock Moth Caterpillar

These caterpillars are native to North America, with a wide distribution ranging from Alaska to Mexico.

They feed on diverse host plants such as willows, birch, and blueberry. Spotted tussock moth caterpillars are characterized by:

  • Yellow and black markings
  • Long, soft, hair-like structures

Despite their vibrant appearance, these caterpillars are not known to be harmful to humans upon contact.

Other Species

Tussock moth caterpillars can also be found in other parts of the world such as Europe, Africa, and Asia.

Various species may have different physical characteristics, feeding habits, and effects on humans or the environment.

SpeciesLocationPhysical DescriptionKnown Effects on Humans
Gypsy MothEurope, Asia, Africa, North AmericaYellowish-brown with blue and red spotsDefoliation of forests may have indirect consequences for humans
White-marked Tussock Moth CaterpillarNorth AmericaWhite hairs with red spots, black marks on the sidesMay cause skin irritation when touched

In conclusion, while some tussock moth caterpillars, like the hickory tussock moth, can cause skin irritation, others like the spotted tussock moth caterpillar are not harmful when touched.

Poisonous Bristles and Venom

Bristles and Setae

Tussock moth caterpillars, such as Lophocampa maculata and Lophocampa caryae, possess unique features:

  • Bristles or setae
  • Venomous properties within these setae

These structures create a defense mechanism to deter predators.

The venom in the caterpillars’ setae can cause irritation and discomfort to humans upon contact.

Defense Mechanism

The primary goal of the venomous bristles is caterpillars’ protection. They deter:

  • Birds
  • Small mammals
  • Insects

However, their venom can pose health hazards to humans. Skin contact with setae may lead to:

  • Irritation
  • Rashes
  • Allergic reactions

In some cases, even their hemolymph or other droplets can be toxic, making the caterpillars both poisonous and venomous.

Remember to exercise caution around these creatures to avoid unwanted reactions.

Whitemarked Tussock Moth Caterpillar

Skin Reactions and Allergies

Common Symptoms

Tussock moth caterpillars are known to cause skin reactions such as rashes and itching in humans. Common symptoms include:

  • Itchy rash, similar to a mosquito bite
  • Red welts or irritation at the site of contact

These reactions typically result from direct contact with the caterpillar’s setae or airborne spread of their shed spines, activating mast cells through a protein called thaumotopoein.

Severe Cases

In rare cases, exposure to tussock moth caterpillars can lead to more severe symptoms or even anaphylaxis:

  • Swelling of the face, lips, or tongue
  • Difficulty swallowing
  • Shortness of breath
  • Anaphylactic shock (extremely rare)

These severe cases result from a heightened immune response and hypersensitivity to allergens found within the caterpillar’s setae.

Treatment and Remedies

For mild reactions, treatment options include:

  • Washing the affected area with soap and water to remove caterpillar hairs
  • Applying hydrocortisone cream or calamine lotion to reduce itching
  • Taking antihistamines to mitigate histamine release and minimize swelling

In severe cases, such as difficulty breathing or anaphylaxis, seek medical attention immediately.

An urgent care center or emergency room may be necessary to manage these reactions.

Milkweed Tussock Moth Caterpillar

Habitat and Behavior

Host Plants

Tussock moth caterpillars are a type of insect belonging to the Erebidae family of Lepidoptera.

They can be found feeding on various trees and shrubs, particularly oak, willow, and other deciduous foliage in the United States.

Some specific species, like the white-marked tussock moth, are also known to feed on needles of coniferous trees.

The key host plants of tussock moth caterpillars include:

  • Oak trees
  • Willow trees
  • Deciduous foliage

Seasonal Activity

The seasonal activity of tussock moth caterpillars primarily occurs during the warmer months of the year.

Adult moths typically fly between May and June, and their caterpillars are present from July to September1.

Additionally, the browntail moth’s caterpillars emerge in spring and may cause defoliation of host trees and shrubs2.

Reproduction and Growth

Tussock moth caterpillars, such as the white-marked tussock moth, reproduce through a process that begins with the female moth laying eggs.

Eggs are laid in clusters of up to 100 or more on the underside of leaves1.

As the young larvae feed and grow, they initially feed in groups, but as they mature, they start feeding more solitarily or in smaller clusters1.

In spring, some species’ caterpillars, like the browntail moth, hatch from eggs laid in or on the mother’s cocoon2.

Comparison: White-marked Tussock Moth & Browntail Moth

FeatureWhite-marked Tussock MothBrowntail Moth
Host PlantsOak, willow, conifersOak, willow
Seasonal Activity (Caterpillars)July-SeptemberSpring
Reproduction (Egg-Laying)underside of leavesmother’s cocoon

Prevention and Control

Safe Handling and Removal

Tussock moth caterpillars can cause skin irritation and, in rare cases, anaphylactic reactions. It’s essential to handle them with care:

  • Wear gloves when touching caterpillars
  • Use a soft bristle brush (like a toothbrush) to gently detach them from trees or surfaces
  • Relocate them to a safe area where they won’t cause harm

Remember to keep an eye on natural predators, such as birds and insects, that may help control the population.

Western Tussock Moth Caterpillar

Protective Measures for Trees and Shrubs

Controlling tussock moth caterpillars is essential to protect trees and shrubs from damage. Here are some methods:

  • Prune infested branches to reduce caterpillar numbers
  • Remove egg masses in winter (overwinter) to prevent population growth in spring
  • Introduce natural predators like birds or insects for biological control

Pros and Cons of Control Methods

MethodProsCons
PruningReduces caterpillar populationCan be labor-intensive; might damage the tree
Removing egg massesPrevents population growth in springNeeds to be done in winter; difficult to find
Biological controlNatural process; minimal human effortTakes time; requires a suitable environment

In summary, prevent and control tussock moth caterpillars through safe handling, relocation, and protective measures for trees and shrubs.

Utilize natural predators and targeted removal strategies to keep their population in check and minimize potential health hazards and damage to plants.

Conclusion

To conclude, certain tussock moth caterpillars can trigger skin irritation due to their bristle-like setae.

The Hickory Tussock Moth Caterpillar, for instance, may cause itching and rashes upon contact.

Be cautious when handling, as reactions differ among individuals.

To stay safe, observe from afar and avoid direct contact with these caterpillars.

Footnotes

  1. Hickory Tussock Moth Caterpillar  2 3
  2. Whitemarked Tussock Moth  2

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about tussock moth caterpillars.

Scroll down to have a look at some of them.

Letter 1 – White Marked Tussock Moth Caterpillar: Caution

I do not know what this is
Location: DeKalb Illinois
October 30, 2011 10:51 pm
I was sitting at a table outside on my schools campus when I looked down at my arm and this thing was climbing up my arm.

I have no idea what it is and cannot find any sort of description of it.
Signature: Desmond Wafers

White Marked Tussock Moth Caterpillar

Hi Desmond,
This caterpillar is a White Marked Tussock Moth or Rusty Vapor Moth,
Orgyia leucostigma. 

The caterpillars from this genus are quite distinctive and they should be handled with care.  According to BugGuide:  “CAUTION:  Contact with hairs may cause an allergic reaction.”

Letter 2 – White Marked Tussock Moth Caterpillar

Subject: Interesting Ohio find

Location: Central Ohio USA
September 14, 2014 12:22 pm
Just the obvious questions of “What the blank is this?” and “Can it hurt me?” come to mind when looking at this.

It caused my sister’s adrenaline to pump and just about everyone else’s skin to crawl, but I suspect it’s a harmless (to humans) caterpillar. Unless you eat it maybe?


Signature: Jack

White Marked Tussock Moth Caterpillar
White Marked Tussock Moth Caterpillar

Dear Jack,
This is the caterpillar of a White Marked Tussock Moth,
Orgyia leucostigma, and according to BugGuide

“CAUTION: Avoid handling the caterpillar, as its hair is known to cause allergic reactions, especially in areas of the body with sensitive skin (e.g. back, stomach, inner arms). Seek medical treatment if a severe reaction occurs.”

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com 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.

  • 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.

10 thoughts on “Are Tussock Moth Caterpillars Poisonous? Uncovering the Truth”

  1. I have these annoying caterpillars in my yard and I am in Houston, TX, how can I get rid of them? I am a caterpillarb lover, but I have small kids and don’t want them to get hurt by them. They are constantly falling out of our huge oak tree next to our portch and crawling all over everything. We can’t even eat out side because they are everywhere.

    Reply
  2. When I was younger I saw one of these and I let it crawl on my arm. Nothing happened!
    Same thing with my sis. I guess we’re lucky.

    Reply
    • Many caterpillars are raised in captivity and we suspect a White Marked Tussock Moth Caterpillar will survive fine with the proper care.

      Reply

Leave a Comment