The puss caterpillar (Megalopyge opercularis) is the larvae of the Flannel Moth (Phalaena opercula).
This alarmingly dangerous insect can be found in many parts of the United States toward the end of summer with other garden pests.
The Southern Flannel Moth is also sometimes called the “Yellow Egger Moth. The puss caterpillar is also known as:
- Possum Bug
- Woolly Slug
- Italian Asp
- ASP – [source]
Although these slow-moving creatures look a bit cute and cuddly, if you touch one you could end up hospitalized or worse.
In this article, we will describe this pest and share information for preventing or dealing with puss caterpillar infestation and dealing with stings. Read on to learn more.
What Do Puss Caterpillars And Asps Look Like?
These poisonous caterpillars are small and unobtrusive. They may be between an inch and an inch-and-a-half long and are covered with smooth, fuzzy venom-coated fur which may be white, gray, brown, rust-colored or even bright orange.
Like all caterpillars, they eventually metamorphose.
As adults, they are Flannel moths which may be orange or yellow, and they have furry, black feet. The moths cannot hurt you, but it’s a good idea to keep them under control to prevent them from reproducing.
The Venomous Hairy Caterpillar Fur Is Dangerous
As a means of self-defense, the puss caterpillar’s venomous fur is quite effective.
When you come in contact with it you’ll feel immediate and intense pain.
Many people say the pain inflicted is worse than you would experience from a scorpion sting or contact with a jellyfish.
In addition to being painful, exposure can cause a sudden reduction in blood pressure, vomiting and/or seizures.
If you are allergic to insect venom, coming in contact with a puss caterpillar can send you into anaphylactic shock and may result in death.
Where Do You Find Puss Caterpillars?
These caterpillars can be found throughout the eastern and southern US and into Texas. They are especially problematic in warm, humid climates such as Florida.
They feed on all sorts of vegetation including veggies, ornamental plants, weeds, grass, shrubs and trees. This is why vigilance is your very best defense against them.
They like to conceal themselves on tree bark and can often be found (with careful scrutiny) on the bark of:
- Citrus trees
Avoid planting these species of trees and shrubs to discourage puss caterpillar infestation. Always look before you reach. Avoid brushing against plants and trees. Wear long sleeves and pants when in the woods.
How Do You Treat Puss Caterpillar Stings?
If you aren’t in immense pain, you can try removing the tiny, venomous hairs from your skin by pressing a piece of tape over them gently and then lifting.
Ammonia can be used initially to neutralize the venom.
Flush the area with cold water and then wash with lukewarm water and soap. If you are stung, apply ice to numb the stinging.
After cleaning and icing, you may wish to use an over-the-counter insect bite or sting preparation to reduce itching and stinging as you go about your day.
Exposure over a large area of skin may require a visit to the doctor.
If you are experiencing intense pain and/or any of the other, more severe symptoms associated with exposure, head for the Emergency Room.
Do These Bugs Actually “Sting”?
Even though these caterpillars do not have a stinger like a wasp, hornet or bee, the injury they inflict is still called a sting.
In the place of a single stinger, puss caterpillars have a set of spines (urticaceous setae) covering the entire body.
The spines are hollow and each one is full of toxin, which is produced by poison gland cells.
This “system” is very effective for protecting the caterpillars from predators.
It is important to understand that this system is entirely defensive. These bugs are all about self-defense.
The caterpillars do not attack, and they have no reason to seek out humans to hurt.
You will only suffer from a sting if you pick one up or inadvertently brush against it.
When you do, the caterpillar may eject hairs or the hairs may break off and release toxins.
If the hairs penetrate your skin, or the toxin spills out onto the surface of your skin, you will feel pain.
How To Identify Stinging Caterpillars
Of all venomous caterpillars, the Asp is considered to be most toxic. The basic puss caterpillar is covered in smooth fur and colored as described above.
Be aware that this is not the only type of stinging caterpillar.
There are a quite a few others (saddleback caterpillar for example) that sting using fur, horns, eversible glands (glands that can be turned inside out) and a number of other ingenious devices to deliver venom.
Venomous caterpillars are typically highly camouflaged. This is their first line of defense against being eaten.
Their second line of defense is to sting, shoot venom or embed venomous hair into their attackers.
Interestingly, puss caterpillars also shoot their droppings (frass) quite a distance as a way of avoiding being located by potential predators.
Not every hairy caterpillar is venomous; however, it is always a good idea to simply leave caterpillars alone when you see them.
The best thing you can do is keep your eyes open and avoid them. In terms of control, methods used to control all caterpillars are effective for puss caterpillars.
7 Natural Methods For Controlling Puss Caterpillars Without Chemicals
Unless your garden is highly infested, you needn’t do anything special to get rid of these creatures. Just treat for caterpillars in general and be vigilant.
The active period for puss caterpillars ( summer’s end) is short, and waiting it out is just as effective (and not as dangerous) as applying poisons.
Here are 7 simple, natural methods you can use to keep these caterpillars under control:
Remove Host Plants
Remove potential host plants early in the season before Flannel Moths and Puss caterpillars have a chance to be attracted to them.
Apply Bacillus thuringiensis (Bt)
Bacillus thuringiensis (Bt) is a natural bacterium that is effective for killing many types of caterpillars. It is readily available online and at your local garden center.
You can dust plant leaves with Bt early in the springtime and at regular intervals throughout the growing season to keep all sorts of caterpillars under control.
Avoid using Bt on or around plants that attract butterflies because it will kill off butterfly caterpillars as well as pest caterpillars.
Use Natural Predators
Use the help of natural predators. Parasitic wasps (Braconid wasps), predator tachnid flies, stink bugs and lacewings are just as effective against venomous caterpillars as they are against non-venomous ones.
Knock Off The Pests
Carefully knock the pests off plants when you see them and step on them. Then be careful not to touch the soles of your shoes for quite some time.
Bucket Of Soapy Water
If you’d prefer not to stomp on caterpillars, you can drop them into a bucket of soapy water.
It’s a good idea to keep one handy at all times when gardening as this is a simple, effective way to deal with all sorts of creatures that can be picked off by hand.
Just add a teaspoonful of dish soap to a gallon bucket of hot water to make an effective solution for immobilizing and drowning all sorts of pests quickly.
Be sure to dispose of the dead caterpillars safely. Some recommend flushing them down the toilet – but not me!
Wash the bucket thoroughly to prevent accidental contact with any venom that may remain on its surface.
The bucket you use for this purpose should be designated and should not be used for other purposes such as carrying bird seed, or gathering produce.
Kill Them On Contact
Kill on contact. These caterpillars can also be killed on contact with a squirt of strong essential oil such as orange, cedar or rosemary.
Carry it in a small squeeze bottle and squirt it on the caterpillars as you find them.
Suck Them Up
Use a shop vac with a disposable bag to suck up the caterpillars.
Put the bag in a black plastic bag and set it in the sun for a few days before sending it off with the trash.
Mark the bag as being hazardous and bury it deeply in the trash to prevent accidental contact with the potentially dangerous contents.
More details on How To Control Caterpillars Eating The Leaves On My Plants
Use Pesticides Only When Absolutely Necessary
If you have a big, threatening infestation that is hard for people to avoid, you may wish to spray with a pesticide to kill them off.
This should be a last resort, though, as it will also kill beneficial insects.
Effective pesticides include:
Be sure to follow packaging instructions carefully when using poisons.
If you have a heavily infested area, it is a good idea to mark it clearly. You may wish to use yellow CAUTION tape.
While this may seem a bit dramatic, remember that these caterpillars can land you in the hospital or the mortuary, so buying and using an inexpensive role of yellow tape to warn others is really a very reasonable precaution.
These pests tend to amass in a small area, so your cordoned off space will not be very big.
When you begin treatment, inspect every day for signs of caterpillars. Even after treatment, continue to monitor areas where the pests have been seen.
You may need to treat several times or combine a variety of management techniques to gain complete control of the population. [source]
3 Steps To Protect Yourself During A Puss Caterpillar Infestation!
When tackling a puss caterpillar infestation, follow these steps:
Protect Your Skin And Eyes
Wear proper protection for your skin and your eyes. This should include long sleeves and pants, goggles, heavy-duty rubber gloves and a broad-brimmed hat.
Understand that these caterpillars may drop out of the trees onto you while you are treating for them, so a hat with a wide brim is very important to prevent one from falling down the back of your shirt!
Check your clothing frequently while working and if you find one, drop it into a bucket of soapy water.
Avoid Contact – Look Before You Reach
Avoid contact with Asps by looking before you reach. When the time comes for the caterpillars to spin a cocoon, they will travel.
They may be found anywhere during this time, so be especially vigilant.
Don’t touch, sit on or lean against anything without first checking for the “Toxic Toupee”. [source]
Avoid Areas Visited By Puss Caterpillars
Avoid handling any surface puss caterpillars may have frequented. They are just as dangerous dead as alive, so handle with care.
What Is The Best Puss Or Asp Caterpillar Treatment Strategy?
Vigilance, manual removal and working in concert with natural predators is the control method used by coffee growers in Central America.
They cannot use chemicals, which would contaminate the coffee beans.
They simply keep a sharp eye out, remove and stomp on the caterpillars as needed and rely on natural predators to do the rest.
It is always better to prevent pest infestation than to battle it.
Simply implementing an integrated pest management (IPM) plan to deal with caterpillars in general, is the wisest course of action.
It is also smart to take steps to discourage moths.
Physical removal, vigilance and the use of natural predators is an effective combination of pest management methods when dealing with these caterpillars.
The parasitic tachinid fly has been found to be the most efficient natural predator, so it is wise to avoid using pesticides or any method that would reduce your population of these flies.
Using natural products may not kill as many of the pests as a pesticide would, but it also won’t kill off all your predators.
In fact, if you see a sudden surge in puss caterpillars it is an indication that their natural enemies have been killed off.
Carefully avoiding the use of pesticides will support the return of the natural predators and the decline of the puss caterpillar population.
For lots of excellent images and additional info at University of Florida “Featured Creatures.”