Puss Caterpillar

Megalopyge opercularis

Last updated: January 24, 2023
Verified by: AZ Animals Staff
© Brett Hondow/Shutterstock.com

The puss caterpillar is the most venomous caterpillar in North America!

Puss Caterpillar Scientific Classification

Kingdom
Animalia
Phylum
Arthropoda
Class
Insecta
Order
Lepidoptera
Family
Megalopygidae
Genus
Megalopyge
Scientific Name
Megalopyge opercularis

Read our Complete Guide to Classification of Animals.

Puss Caterpillar Conservation Status

Puss Caterpillar Locations

Puss Caterpillar Locations

Puss Caterpillar Facts

Prey
tree leaves
Main Prey
oak leaves
Name Of Young
N/A
Group Behavior
  • Eclipse
Fun Fact
The puss caterpillar is the most venomous caterpillar in North America!
Estimated Population Size
Undetermined
Biggest Threat
habitat loss through deforestation.
Most Distinctive Feature
The puss caterpillar's most distinctive feature is the venomous spines on its body, which can cause severe skin reactions and even serious injury if touched.
Distinctive Feature
setae, the bristly hairs that cover their bodies.
Other Name(s)
woolly slug caterpillar
Gestation Period
N/A
Temperament
docile
Wingspan
N/A
Training
N/A
Optimum pH Level
N/A
Incubation Period
N/A
Age Of Independence
birth
Age Of Fledgling
N/A
Average Spawn Size
N/A
Litter Size
N/A
Habitat
wooded areas, gardens, and residential neighborhoods. They are known to be particularly common in oak-hickory forests and pine-hardwood forests.
Predators
birds, spiders, wasps, ants
Diet
Herbivore
Average Litter Size
N/A
Lifestyle
  • Diurnal
Favorite Food
oak leaves
Type
Megalopyge opercularis
Common Name
Puss caterpillar
Special Features
Highly venomous
Origin
North America
Number Of Species
250
Location
North America
Slogan
N/A
Group
eclipse
Nesting Location
N/A
Age of Molting
The puss caterpillar molts 5-6 times throughout its growth period.

Puss Caterpillar Physical Characteristics

Color
  • Brown
  • Grey
  • Yellow
  • White
  • Orange
Skin Type
Exoskeleton
Lifespan
1 week - 5 weeks
Weight
less than 1 ounce
Height
0.25 - 0.5 inches
Length
0.5 - 1 inch
Age of Sexual Maturity
N/A
Age of Weaning
N/A
Venomous
Yes
Aggression
Low

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The puss caterpillar (Megalopyge opercularis), also known as the Southern flannel moth caterpillar, is a venomous caterpillar found in the Southeastern United States and Mexico. It has a dense covering of what appear to be soft, fluffy hairs that resemble fur. However, these hairs, or setae (singularly, seta) are anything but soft! The setae contain venom which causes severe pain, nausea, and difficulty breathing. They should not be touched, and if contact is made with one and a reaction ensues, seek medical attention immediately! They are not aggressive and cannot move swiftly, so they are rather easy to avoid if you know what you’re looking for. keep reading to learn everything you need to know about the puss caterpillar.

Five Furry Facts about Puss Caterpillars

  • The puss caterpillar is the most venomous caterpillar in North America!
  • They are covered in dense hairs that are filled with venom that causes a severe sting if touched. The venom from the sting can cause pain, redness, swelling, and in some cases, an allergic reaction or even anaphylaxis.
  • Puss caterpillars are typically brown or gray and have long, tufted setae, which are bristly hairs, that give them a furry appearance.
  • They are typically found on trees, shrubs, and other plants, and are most active in the late summer and early fall.
  • Puss caterpillars are not aggressive, but they will sting if they feel threatened or if they are touched. To avoid getting stung, it is best to avoid handling or disturbing them.

Scientific Name

The Puss caterpillar shares its scientific name, Megalopyge opercularis, with its adult form, the Southern flannel moth. Megalopyge translates to large bottom, while opercularis is Latin for cover. Popular thought suggests that the name refers to the adult form’s pear shape and the way in which they emerge from the top of their cocoons as if removing a cover or lid.

Appearance

Puss caterpillars, also known as woolly slug caterpillars, are the larvae of the Southern flannel moth. They are covered in dense hairs that can cause severe itching and allergic reactions in humans who come into contact with them. In some cases, the venom from the hairs can even cause serious medical conditions such as chest pain, difficulty breathing, and muscle cramps. The venom is present in the hair follicles, so even if the hairs appear to be brushed off, the venom may remain on the skin and cause a reaction.

Puss caterpillars typically appear fuzzy and have a gray or brown coloration. They may have black-and-white markings on their bodies. Some individuals have an orange or yellow line running the length of their bodies. They are typically about 1 inch long and weigh less than 1 ounce when fully grown. Females tend to be a bit larger than males. Southern flannel moth caterpillars, like most caterpillars, do not have antennae. They have a head, thorax, and multiple segments on their body called abdominal segments.

Macro of a Southern flannel moth caterpillar, called a puss caterpillar. It s covered in lkhaki colored hair. It is is rounder on the end in the left frame. The end in the right frame comes to a point. It is on a green leaf with visible veins.
The puss caterpillar is the most venomous caterpillar in North America!

©Brett Hondow/Shutterstock.com

Behavior

Southern flannel moth caterpillars are slow-moving and typically found on the foliage of trees and shrubs. Puss caterpillars feed on leaves and can cause damage to plants if there are large populations present. They typically rest on the underside of leaves during the day and are active at night. They are not known to be aggressive but are venomous.

Habitat

Puss caterpillars are found throughout the Southeastern United States, from the Carolinas to the Gulf Coast, and Mexico. They are most commonly found in wooded areas, gardens, and residential neighborhoods. Puss caterpillars are particularly common in oak-hickory forests and pine-hardwood forests. They feed on a variety of trees and shrubs such as oak, pecan, apple, and plum. In the wild, they tend to be found on the leaves of trees and shrubs, but when they are in urban or residential areas, they can also be found on bushes and even on the ground, parking in broadleaf groundcover plants.

Diet

Southern flannel moth caterpillars are known to feed on the leaves of a variety of trees and shrubs, including oak, pecan, apple, and plum. They are known to be particularly fond of oak leaves. The caterpillars are also known to feed on other plants such as hickory, elm, and sweetgum. They tend to feed in groups, which can cause significant damage to foliage if there are large populations present. They are known to be herbivores feeding primarily on plants.

However, they are opportunistic eaters that will eat the fruit of agricultural crops. Puss caterpillars cause damage to a variety of crops, including cotton, peanuts, and corn. They feed on the leaves and fruit of these plants, causing defoliation and reducing crop yields. Their feeding can cause cotton bolls to open prematurely, making the cotton inside the bolls unmarketable. They can also injure livestock and humans if contact is made. Control measures, such as the use of pesticides and the introduction of natural predators, can be used to mitigate the damage caused by puss caterpillars.

Predators

Puss caterpillars have a variety of natural predators. These include birds, such as warblers, vireos, and thrushes, as well as mammals like raccoons, opossums, and skunks. They can also be preyed upon by other insects, such as wasps and ants. Paper wasps lay their eggs on or inside the caterpillars. Their larvae then feed on the caterpillars as they develop. Additionally, spiders have been known to feed on puss caterpillars. These predators help to keep puss caterpillar populations in check and prevent overpopulation, which can cause damage to trees and plants.

Threats

Puss caterpillars face several threats. These caterpillars are at risk of exposure to pesticides and herbicides used in agriculture. Climate change and habitat destruction may also affect the population of these venomous caterpillars. Habitat destruction, in the form of deforestation, is the primary threat to the continued existence of the puss caterpillar. Puss caterpillars in agricultural settings will almost certainly be annihilated by some heavy-duty pesticide.

Conversation Status

The conservation status of the Puss caterpillar (Megalopyge opercularis) is not listed. It is not considered a threatened or endangered species and it is not listed under any conservation acts. However, it’s important to note that the conservation status of a species is subject to change as new information becomes available and populations may be affected.

Puss Moth: Lifecycle

The puss caterpillar goes through four stages in its lifecycle: egg, larva (caterpillar), pupa, and adult. The eggs are laid in clusters on the leaves of trees such as oak, hickory, elm, and sweetgum. and shrubs. The eggs hatch in about 7 to 10 days. The larval stage lasts for 4 to 6 weeks, during which time the caterpillar feeds on the leaves of various trees and shrubs, including oak, pecan, and elm. As they grow, they shed their skin several times. This shedding is called an instar. Puss caterpillars are not well-studied, but they are thought to have 5-6 instars or periods of molting.

When they reach full size, they spin cocoons and enter the pupal stage, which lasts from 2 to 3 weeks. The process of metamorphosis that the caterpillar goes through in the cocoon includes several stages: the caterpillar spins a silk cocoon around itself and then molts into a pupa. Inside the pupa, the insect’s body undergoes a complete transformation, during which the wings and other adult structures develop. Finally, the adult moth emerges from the cocoon and is active for about a week, during which time they mate and lay eggs to start the cycle again.

The cocoon of a puss caterpillar is visible center frame. It is attached to a Y shaped tree limb. The limb is horizontal, making the Y of the limb sideways. The cocoon which is mostly shades of gray, is triangular with it'd point facing down. The cocoon is attached to th lower lomb. right below ere it forks into a sideways Y. Against blue isolate.
When they reach full size, puss caterpillars spin cocoons and enter the pupal stage, which lasts from 2 to 3 weeks.

©Lacy L. Hyche, Auburn University, United States, CC BY-SA 3.0 – License

Population

It is difficult to provide an accurate estimate of the population of puss caterpillars. Because they are relatively widespread, and not readily visible during certain developmental stages, their population is difficult to gauge. Their populations can fluctuate from year to year depending on a variety of factors, such as weather conditions and the availability of food.

Wound Care

If you accidentally brush up against a puss caterpillar the first thing you should do is: Don’t panic! Their stings are seldom life-threatening. Then remove any setae using scotch tape. If scotch tape isn’t available, other types of tape will suffice. However, always proceed with caution, following the wishes of the injured party. Placing the tape over the site of the sting lifts out the hairs which contain the venom. Next, wash the area gently, but thoroughly with soap and water. A tincture of comfrey will remove some of the sting, as will baking soda when placed directly on the wound site. If you feel short of breath, dizzy, or have other symptoms that would suggest an allergic reaction, seek medical attention immediately! Otherwise, take it easy and the pain of the sting should dissipate momentarily.

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About the Author

Hi! I'm Kat, and my favorite animals are river otters and goldfinches. Baking, gardening, and sewing are my favorite pastimes. I live with two people and two dogs.

Puss Caterpillar FAQs (Frequently Asked Questions) 

Is the puss caterpillar venomous?

Yes! In fact, the puss caterpillar is thought to be the most venomous caterpillar in North America. The pain of its sting has been compared to that of a heart attack or limb amputation. Let’s have a moment of silence for the individuals who are able to make those comparisons, especially the latter.

Besides pain, The venom from the sting can cause redness, swelling, and in some cases, an allergic reaction or even anaphylaxis.

What do puss caterpillars like to eat?

Puss caterpillars feed on the leaves of a variety of trees and shrubs, including oak, pecan, apple, and plum. They are known to be particularly fond of oak leaves. The caterpillars also feed on other plants such as hickory, elm, and sweetgum. They tend to feed in groups, which can cause significant damage to foliage if there are large populations present.

Where do puss caterpillars live?

Puss caterpillars are indigenous to North America. They are primarily found in the Southern United States from the Carolinas to Texas, and Mexico. They are most prevalent around the Gulf Coast.

What do puss caterpillars look like?

Puss caterpillars typically appear fuzzy and have a gray or brown coloration. They may have black-and-white markings on their bodies. Some individuals have an orange or yellow line running the length of their bodies. They are typically about 1 inch long and weigh less than 1 ounce when fully grown.

What should you do if you accidentally brush up against a puss caterpillar?

If you accidentally brush up against a puss caterpillar the first thing you should do is: Don’t panic! Then if possible remove any setae using scotch tape. Next, wash the area gently, but thoroughly with soap and water. If you feel short of breath, dizzy, or have other symptoms that would suggest an allergic reaction, seek medical attention immediately! Otherwise, take it easy and the pain of the sting should dissipate momentarily.

Thank you for reading! Have some feedback for us? Contact the AZ Animals editorial team.

Sources
  1. ufl.edu, Available here: https://entnemdept.ufl.edu/creatures/misc/moths/puss.htm
  2. insectidentification.org, Available here: https://www.insectidentification.org/insect-description.php?identification=Southern-Flannel-Moth
  3. wikipedia.org, Available here: https://en.wikipedia.org/wiki/Megalopyge_opercularis

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