Asp Caterpillar

Last updated: February 9, 2023
Verified by: AZ Animals Staff
© Chase D'animulls/Shutterstock.com

The venom of some species of asp caterpillars is used in medicine.


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Asp Caterpillar Scientific Classification

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

Read our Complete Guide to Classification of Animals.

Asp Caterpillar Conservation Status

Asp Caterpillar Locations

Asp Caterpillar Locations

Asp Caterpillar Facts

Prey
tree leaves
Main Prey
tree leaves
Name Of Young
N/A
Group Behavior
  • Solitary
Fun Fact
The venom of some species of asp caterpillars is used in medicine.
Estimated Population Size
Undetermined
Biggest Threat
pesticides
Most Distinctive Feature
furry body
Distinctive Feature
coloration
Other Name(s)
Southern flannel moth, yellow flannel moth, Eastern tent caterpillar, et al.
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
Asp caterpillars are found in a variety of habitats depending on the specific species. Some are found in woodlands, while others are found in more open areas such as fields and gardens.
Predators
Birds, small mammals, wasps, hornet, spiders
Diet
Herbivore
Average Litter Size
N/A
Lifestyle
  • Diurnal
Favorite Food
tree leaves
Type
Megalopyge
Common Name
asp caterpillar
Special Features
bristly hairs that contain venom
Origin
North America
Number Of Species
45
Location
North America; Central America
Slogan
N/A
Group
Megalopygidae
Nesting Location
trees
Age of Molting
various times throughout larval stage

Asp Caterpillar Physical Characteristics

Color
  • Multi-colored
Lifespan
1 week - 1 year
Weight
less than 1 ounce
Height
0.25-0.5 inches
Length
1-2 inches
Age of Sexual Maturity
N/A
Age of Weaning
N/A
Venomous
Yes
Aggression
Low

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An asp caterpillar is a type of caterpillar that can be found in various regions of the world, including North America. They are known for their venomous spines, which can cause skin irritation and, in rare cases, more severe reactions such as anaphylaxis. Some species of asp caterpillars are also known for their bright colors and distinctive patterns. They typically feed on the leaves of trees and shrubs. Keep reading to learn more about these amazing creatures!

Five Fun Facts about Asp Caterpillars

  • Some species of asp caterpillars have venomous spines that can cause skin irritation and in rare cases more severe reactions, such as allergic reactions, when they come into contact with human skin.
  • The venom of some species of asp caterpillars is used in traditional medicine in some parts of the world.
  • The venomous spines of asp caterpillars do not deter many birds as they are not affected by the venom.
  • Some species of asp caterpillars have a symbiotic relationship with ants, in which the ants will protect the caterpillars from predators in exchange for sugars and amino acids secreted from the caterpillar’s dorsal nectary organ.
  • Some species of asp caterpillars, such as the Eastern tent caterpillar (Malacosoma americanum), are known to construct communal nests or tents made of silk, which they use to protect themselves from the elements and predators.

Scientific Name

The scientific name for the asp caterpillar varies depending on the specific species. Some examples include the puss caterpillar (Megalopyge opercularis) which is found in the Southeastern United States, the flannel moth caterpillar (Megalopyge lanata) which is found in the Southwestern United States and the Southern flannel moth caterpillar (Megalopyge pyxidifera) which is found in the Southeastern United States. These are the most commonly known asp caterpillars
Asp caterpillar is a common name for the caterpillars of several species of moths in the family Megalopygidae. The exact number of species within this family is not well established and is likely to change as new discoveries and taxonomic revisions are made. However, currently, the family Megalopygidae is considered to have around 15-20 species worldwide

Appearance

Asp caterpillars, also known as flannel moth caterpillars, have a distinctive appearance. They are typically fuzzy, with long, stiff spines or setae (singularly seta) covering their bodies.
Their coloration and patterning can vary depending on the species, but many have bright and contrasting colors, such as yellow, orange, white, and black, which can help them stand out and deter predators. Some species also have tufts of longer, hair-like setae on their heads and tails that can also be venomous. They typically range in size from 1 to 2 inches long, weighing less than 1 ounce.
Many species have venomous spines or setae on their bodies that can cause skin irritation, burning sensations, and in rare cases more severe reactions such as anaphylaxis. The venom is not harmful to humans, but the stinging sensation and irritation can be quite unpleasant. The venomous setae on their body can be easily brushed off when they come into contact with skin. It’s important to handle them carefully and avoid touching them if possible, or if handling them is necessary, wear gloves.

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Asp Caterpillars of North America

Some species of asp caterpillars found in North America are:

  • The Southern flannel moth caterpillar (Megalopyge pyxidifera), is found in the Southeastern United States.
  • The Eastern tent caterpillar (Malacosoma americanum), is found in the Eastern United States and Canada.
  • The hickory tussock moth caterpillar (Lophocampa caryae) is found in the Eastern United States and Canada.
  • The white flannel moth (Norape ovina) is found throughout the United States
  • The crinkled or black-waved flannel moth (Lagoa crispata) is found throughout the Eastern United states
  • The yellow flannel moth (Lagoa pyxidifera) is found in the Eastern United States.
  • The puss caterpillar (Megalopyge opercularis) is found throughout the Southern United States
  • The flannel moth caterpillar (Megalopyge lanata)is founded in the Southeastern United States.
Caterpillar of the Southern flannel moth on oak leaf. The caterpillar is cover in light hairs with a rusty-orange strip dissecting the length of its body. It is on a green oak leaf.
The Southern flannel moth (Megalopyge pyxidifera), is found in the Southeastern United States.

©IrinaK/Shutterstock.com

Behavior

Asp caterpillars are solitary and are most active during the day. They feed on the leaves of trees and shrubs, and they are known to be voracious feeders. They can be found crawling on the ground, on tree trunks, and on branches.
When they feel threatened, they will curl up to protect themselves, while displaying the venomous spines on their body. This is a defensive tactic to deter predators.
When fully grown, they will spin cocoons and metamorphose into moths. The adult moths are typically nocturnal and have earthy coloration and small size. Their main role is to reproduce.
There are variations in the behavior of different species of asp caterpillars. Behavior is also influenced by the environment, temperature, availability of food, and other factors.



Asp caterpillars are not considered major pests. They are considered generalist feeders and have a broad range of host plants, which means that they can feed on many different types of trees and shrubs. They typically feed on the leaves of their host plants, which can cause some defoliation, but generally not enough to cause significant damage to the plant. However, in some cases when there is a high population density of asp caterpillars and the food resources are limited, they can cause some damage to the host plant, which can affect the ecosystem. Caterpillars are an important food source for many species of birds and other animals, and therefore play an important role in the ecosystem by providing food for predators

Habitat

Asp caterpillars are found in a variety of habitats depending on the specific species. Some are found in woodlands, while others are found in more open areas such as fields and gardens. They can be found throughout North America, as well as in other regions of the world.
Many species of asp caterpillars are associated with deciduous trees and shrubs, such as oak, hickory, elm, and cherry. They are typically found on the leaves of these plants, where they feed and grow. They also form their cocoons on the branches of the host tree or shrub, or on nearby structures, such as fences or buildings. The habitats of asp caterpillars vary depending on the stage of their life cycle, with caterpillars typically found on leaves while adult moths tend to be found on flowers or other nectar sources.

Diet

Asp caterpillars are generalist feeders, which means that they can feed on a wide range of host plants. Their diet typically consists of the leaves of trees and shrubs, depending on the specific species. Some common host plants include oak, hickory, elm, and cherry.
During the caterpillar stage, they feed voraciously and can consume large amounts of leaves, which can cause some defoliation. However, as mentioned earlier, it is generally not enough to cause significant damage to the host plant.
Once they become adult moths, they do not feed at all as they do not have functional mouths. They have vestigial mouths. Vestigial is defined as relatively unformed and not functional. Since they are unable to eat, they rely on energy stores from their larval stage. Those stores are readily depleted as they mate and lay eggs. They die soon thereafter. The diet of asp caterpillars can vary depending on the specific species and the availability of host plants in their environment. They are opportunistic feeders and will feed on whatever plants are readily available

Predators

Asp caterpillars have a variety of predators depending on the specific species and their environment. Some common predators include:

  • Birds: Many species of birds, such as warblers, vireos, and woodpeckers, will feed on asp caterpillars. The venomous spines of asp caterpillars do not deter many birds as they are not affected by the venom.
  • Wasps and hornets: Some species of wasps and hornets, such as paper wasps, yellow jackets, and hornets, will feed on asp caterpillars. They will sting the caterpillars to paralyze them and then carry them back to their nest to feed their young.
  • Insect-eating mammals: Some species of mammals, such as opossums, raccoons, skunks, and squirrels, will feed on asp caterpillars.
  • Parasitoid insects: Some species of parasitoid insects, such as ichneumonid wasps and braconid wasps, will lay their eggs on or in asp caterpillars, and the developing parasitoids will consume the caterpillar from the inside out.
  • Some species of spiders and beetles also feed on asp caterpillars.

The presence and effectiveness of predators will vary depending on the specific species and the environment.

Threats

Threats that Asp Caterpillars Face

Asp caterpillars, also known as flannel moth caterpillars, face a variety of threats depending on the specific species and their environment. Some common threats include:

  • Habitat loss: As with many other species, habitat loss is a major threat to asp caterpillars. The destruction of natural habitats, such as woodlands and fields, can reduce the availability of host plants and limit the populations of asp caterpillars.
  • Pesticides: The use of pesticides poses a threat to asp caterpillars. Pesticides can kill or harm the caterpillars directly, as well as the predators that feed on them.
  • Climate change: Climate change can also affect asp caterpillars by altering the timing of the seasons, which can disrupt the timing of their life cycle and affect their ability to find food and reproduce.
  • Competition: Competition for food and other resources can also be a threat to asp caterpillars. They may have to compete with other caterpillars and insects for food and other resources.
  • Disease: Some species of asp caterpillars may also be affected by diseases, such as fungal or viral infections, which can reduce their populations.

The threats to asp caterpillars vary depending on the specific species and the environment. Some species may be more or less affected by certain threats depending on factors such as population densities, availability of food, and natural competition

Threats that Asp Caterpillars Pose

Asp caterpillars pose threats to humans and other animals depending on the specific species and their environment. Some common threats include:

  • Venomous spines: Many species of asp caterpillars have venomous spines or setae on their bodies that can cause skin irritation, burning sensations, and in rare cases more severe reactions such as anaphylaxis, when they come into contact with human skin.
  • Defoliation: Asp caterpillars cause some defoliation of trees and shrubs, which affects the health of the host plants, leading to aesthetic damage to landscapes and gardens.
  • Allergic reactions: Some people may have an allergic reaction to the venom from the asp caterpillars’ spines. These reactions can range from mild to severe, and in rare cases, they can be life-threatening.
  • Ecological impact: Asp caterpillars can also have an impact on the ecosystem, as they are a food source for many species of birds and other animals. A significant reduction in their population could disrupt the food chain and have an impact on their predators.

The asp caterpillar poses relatively few threats compared to other species. They are not considered major pests.

Conservation Status

The conservation status of asp caterpillars varies depending on the specific species. Also, the term asp caterpillar is not a scientific name and there are different species with different conservation statuses.
Many species of asp caterpillars are not considered to be endangered or threatened, as they have a broad range of host plants and a wide distribution. They are also considered generalist feeders and are not dependent on any specific habitat, which allows them to adapt to different environments. However, some species may be affected by habitat loss, pesticide use, and other factors that can affect their populations. Conservation status changes over time as new information and research become available. Species are reevaluated and their status is updated accordingly.
If you are trying to identify a specific species, consulting with a local entomologist or university is recommended. They will be able to provide more specific information about the conservation status of a particular species.

Lifecycle

The lifecycle of asp caterpillars involves four stages: egg, larva (caterpillar), pupa, and adult. The exact lifecycle can vary depending on the specific species, but generally follows this pattern:
The adult moths lay eggs on the leaves and branches of host plants, such as oak, hickory, elm, and cherry. After a few days, the eggs hatch into tiny caterpillars, also known as larvae. The larvae begin feeding on the leaves of the host plant. They go through several stages of growth, molting their exoskeleton as they grow. These molts are called instars, and most caterpillars have 5 or 6. As they feed and grow, they become larger and develop the characteristic venomous spines that are associated with asp caterpillars.
Once they have reached maturity, the caterpillars will spin a cocoon, typically on the branches of the host tree or shrub, or on nearby structures. Inside the cocoon, they undergo metamorphosis and transform into pupae. After a few weeks, the pupae emerge as adult moths. Adult moths have a neutral, earth-tone coloration and are small in size. Their main role is reproduction. They typically live for a few weeks, during which they mate and lay eggs to begin the next generation.
The timing of the lifecycle can vary depending on the specific species and environmental conditions, such as temperature and food availability. Some asp caterpillars have one generation per year, while others have multiple generations.

Lifespan

The lifespan of asp caterpillars varies depending on the specific species and environmental conditions. The caterpillar stage is the longest stage of the life cycle, lasting from several weeks to several months. Once they have reached maturity, they will spin a cocoon and transform into pupae. The pupal stage typically lasts a few weeks, during which the caterpillar undergoes metamorphosis and transforms into an adult moth.
The adult moth stage is the shortest stage of the life cycle, lasting a few weeks at most. Adult moths do not feed. Instead, they rely on energy stores from their larval stage. As adult moths, their main role is to reproduce. They mate and lay eggs to begin the next generation. The timing of the lifecycle can vary depending on the specific species and environmental conditions, such as temperature and food availability.

Population

There is no specific population information for asp caterpillars as a group, as the term asp caterpillars is not a scientific name. Asp caterpillars refers to different species with different population sizes. Additionally, population estimates can vary depending on the specific species and location, and they can change over time due to a variety of factors such as habitat loss, pesticide use, and climate change.
Monitoring the population of asp caterpillars and other species is an ongoing process, requiring regular surveys. The population estimates can be affected by many factors such as weather, disease, and predation, which can lead to fluctuations in population numbers.

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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.

Asp Caterpillar FAQs (Frequently Asked Questions) 

Are asp caterpillars venomous?

Many species have venomous spines or setae on their bodies that can cause skin irritation, burning sensations, and in rare cases more severe reactions such as anaphylaxis. The venom is not harmful to humans, but the stinging sensation and irritation can be quite unpleasant. The venomous setae on their body can be easily brushed off when they come into contact with skin. It’s important to handle them carefully and avoid touching them if possible, or if handling them is necessary, wear gloves.

What do asp caterpillars look like?

Asp caterpillars are fuzzy with long, stiff spines or setae (singularly seta) covering their bodies.
Their coloration and patterning can vary depending on the species, but many have bright and contrasting colors, such as yellow, orange, white, and black, which can help them stand out and deter predators. Some species also have tufts of longer, hair-like setae on their heads and tails that can also be venomous. They typically range in size from 1 to 2 inches long, weighing less than 1 ounce.

What do asp caterpillars act like?

Asp caterpillars are solitary and are most active during the day. They feed on the leaves of trees and shrubs, and they are known to be voracious feeders. They can be found crawling on the ground, on tree trunks, and on branches.
When they feel threatened, they will curl up to protect themselves, while displaying the venomous spines on their body. This is a defensive tactic to deter predators.

What is the lifespan of an asp caterpillar?

The lifespan of asp caterpillars varies depending on the specific species and environmental conditions. The caterpillar stage is the longest stage of the life cycle, lasting from several weeks to several months. Once they have reached maturity, they will spin a cocoon and transform into pupae. The pupal stage typically lasts a few weeks, during which the caterpillar undergoes metamorphosis and transforms into an adult moth.

What do asp caterpillars eat?

Asp caterpillars are generalist feeders, which means that they can feed on a wide range of host plants. Their diet typically consists of the leaves of trees and shrubs, depending on the specific species. Some common host plants include oak, hickory, elm, and cherry.
During the caterpillar stage, they feed voraciously and can consume large amounts of leaves, which can cause some defoliation. However, as mentioned earlier, it is generally not enough to cause significant damage to the host plant.
Once they become adult moths, they do not feed at all as they do not have functional mouths.

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

Sources
  1. Illinois.edu, Available here: https://vetmed.illinois.edu/wildlifeencounters/grade9_12/lesson2/adapt_info/specialist.html
  2. tamu.eud, Available here: https://citybugs.tamu.edu/factsheets/biting-stinging/others/ent-3010/
  3. ufl.edu, Available here: https://entnemdept.ufl.edu/creatures/misc/moths/puss.htm
  4. wikipedia.org, Available here: https://en.wikipedia.org/wiki/Megalopyge_opercularis
  5. sciencedirect.com, Available here: https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/megalopygidae
  6. biomedcentral.com, Available here: https://ethnobiomed.biomedcentral.com/articles/10.1186/s13002-017-0136-0

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