Puss caterpillars are extremely common in the southern states. They’re also extremely dangerous.
The get the name “puss” from their color reference to the tiny Persian cat.
These caterpillars are OK to leave alone if they’re not harming your plants. It’s only when there’s visible damage to the plant foliage where pest control is necessary.
Always be careful when inspecting areas with puss caterpillars.
NEVER handle them without protection. Look before you reach. Always consult with a professional pest rep before doing any kind of DIY insect plan. Proceed at your own risk.
In this guide, we’ll cover some basic topics such as:
How to identify puss caterpillars
What they eat and why your garden has them
Natural techniques for getting rid of Asp caterpillars
How to keep them out of your garden
If you have any questions, feel free to leave a comment.
Avoid brushing against the foliage. Always wear long sleeves and pants with decent shoes. Never reach without looking.
If you don’t know what you’re doing, don’t do it. Get a professional’s advice first.
What’s a puss caterpillar?
Puss caterpillars (AKA Asp caterpillars) are the larvae of the southern flannel moth.
Scientifically known as M. opercularis, it’s the larval form of the adult P. opercula. It’s known to be the most venomous caterpillar on the planet because of its dangerous hair. This dangerous caterpillar is natively found all over the US, mainly in Texas or Florida.
While they may look colorful and fuzzy, NEVER touch one directly! Consult with a professional exterminator before doing any kind of pest control.
While the name sounds weird, a puss caterpillar is a common nuisance in the home garden.
You may have heard of them being referred to as Asps. They’re known for their furry bodies which can be orange or brown.
They prefer arboreal foliage, but may be found near gardens or landscaping.
Other names
You may have heard puss caterpillars called:
Asp caterpillar
Wooly slug
Italian Asp
Possum Bug
Perrito
Yellow Eggar Moth
Southern flannel moth caterpillar
Puss moth caterpillar
Puss moth
Southern flannel moth
Fire caterpillar
Woolly slug
Opossum bug
Puss moth
Tree asp
Italian caterpillar
Megalopyge opercularis
The Asp refers to both puss moths and puss caterpillars. It can also mean flannel moths and flannel caterpillars.
So it’s like a 4 in 1 general definition.
Identification – What do they look like?
Puss caterpillars are orange, brown, or black. They can span a range of colors.
They also have a darkened head which is usually orangish but has a small dark fur on top of the darkened color. They have an elongated “tail” end with hair sticking outwards.
Asp caterpillars are known for their fuzzy bodies. Patterned, segmented body sections are divided by black hairs. The rest of the body is solid orange or brown. They can also be silver or charcoal.
They turn into moths called southern flannel moths. These moths are pretty gorgeous in color, but they’re the key to stopping the cycle.
They’re very similar in coloration to their larval counterparts. The moths are white, orange, brown, and black with large beady eyes.
While the moths may be alarming, the caterpillar is the real source of damage to your garden plants.
It eats and does nothing else but pupates in the winter to emerge as an adult moth in the springtime. Get rid of either to stop the infestation of these buggers.
These caterpillars can be other hybrid colors also. They can be yellow or even red-brown. The adult size of these bugs averages 1.3 inches.
The entire body is covered with these hairs. Each time it grows, the hairs get longer. So be careful.
You can tell how old a puss caterpillar is by its hair length. They can get pretty lengthy and will be found hiding on leaf surfaces.
It’s important to properly identify the caterpillar so you know that the techniques you use aren’t going to waste.
These caterpillars are pretty easy to differentiate from others. If you need help, please leave a comment with a picture of the pest for identification.
Lifecycle
Puss caterpillars come from adult flannel moths, which deposit eggs in the leaves of host plants. The caterpillars eat and molt.
Eventually they pupate into moths during the winter. The adult moths emerge in the springtime to repeat the cycle of caterpillars.
Where do they come from?
Puss caterpillars are native to Florida, Arkansas, New Jersey, Texas, Louisiana, George, Mississippi, South Carolina, Tennessee, Oklahoma, Kentucky, and other southeastern zones.
These are the regions that have the highest number of puss caterpillar infestations. They prefer warmer, humid zones. This is why they’re called the southern moth. Makes sense right?
What do they eat?
Asp caterpillars feed on a variety of foliage. But they do have their favorites:
Citrus trees
Basswood
Hackberry
Sycamore
Dogwood
Cherry
Apple
Maple
Plum
Elm
Oak
Veggies, ornamental plants, weeds, grass, shrubs, and trees
If you avoid planting these types of plants, you can reduce the chance of infestations.
Where do they hide?
The puss caterpillar will hide in elms, oak, citrus, or sycamore leaves. These are their preferred host plants.
Sometimes, they can fall into the garden and infest local plants. Since they’re so high up, they’re often hard to see. They hide inside the bark so they can be hard to see.
These caterpillars will live, feed, and breed on the same host plants.
When looking through the foliage for puss caterpillars, use a long, sturdy object to move plant material.
Do not use your bare hands. They hide in leaves within plants, bushes, or trees. If you happen to see puss caterpillars, don’t touch them. They usually hide on leaf surfaces while they feed.
If you see visible flannel moths, you can expect that eggs are hiding somewhere nearby.
Look through your ornamental plants or bushes. If you have elm, ivy, rose bushes, oak, citrus, or other taller foliage, check those first. Inspect your garden carefully.
Look through the landscaping and the soil line because they often fall from heights and will crawl around in search of new places to hide or feed.
When are they active?
These moths are active during the summertime and late spring. The moths emerge from the trapdoor in the cocoon that’s hanging off leaves or branches.
They come out and buzz around to lay hundreds of eggs in foliage. While they have preferred host plants, they can deposit eggs in any plant. Over the summer, the puss moths will emerge to feed on your plants.
Up to 2 generations may be spawned during this time. Southern flannels are found in the fall too.
In winter, southern flannel moths and puss moths will spin cocoons. The color of it varies depending on the caterpillar, which uses its hair to weave the cocoon. It’s usually brown or yellow.
Signs of damage
Asp caterpillars don’t do much damage. But if they’re prevalent, your foliage may suffer some damage.
As you know, the larvae need to eat enough so they can molt and go through a series of instars.
This makes it get bigger until it’s ready to pupate. For established plants, they pose very little threat to them. For younger plants, puss caterpillars can be dangerous.
There are some things you should look for that are a sign of damage:
Visible puss caterpillars at the base of trunks, branches of shrubs, or foliage
Cocoons hanging off leaves in the fall
Flannel moths buzzing around the garden
Damaged leaf edges
Holes in leaves
Egg clusters on foliage
What do they turn into?
Puss caterpillars turn into adult flannel moths. These moths are responsible for mating and then depositing eggs in your plants.
They emerge in the springtime following the winter. The cold doesn’t kill the puss caterpillars, so don’t assume that the winter will get rid of them.
How to get rid of puss caterpillars naturally
Here’s how you can get rid of those puss caterpillars using DIY home techniques.
Remember to always look before you reach, wear protective gear, and using a stick to reach- never your bare hands.
Consult with a professional before starting any DIY pest control program.
Encourage natural predators
Use the power of natural predators to help kill off some of the caterpillars.
With the help of parasitic wasps, tachinid flies, lacewings, or stink bugs, can help feed on the puss caterpillars to reduce their numbers.
Check which of these buggers are in your hardiness zone and do some reading on how to bring in more of them to your garden. They may help with the puss caterpillar population.
Dunk them into a bucket
This doesn’t mean you use your hands to pick them off.
It means getting a bucket and filling it up with soapy water. Then place it right under the puss worms and then shake the plant to loosen them. They’ll fall into the bucket.
Wear protective gear. Use a stick or something to shake the plant. Don’t use your bare hands. You never know where they’re hiding. The soapy water can kill the puss caterpillars easily.
If you find that they’re not being affected, try increasing the volume of soap you use.
You can also dunk the entire branch with foliage into the bucket if you want. This is a quick way to sanitize the branch. 1 tsp of dish soap to a gallon of hot water is enough to quickly drown them.
Dispose of the puss caterpillars carefully. Dispose of the bucket too. Consider it contaminated after each use. Or solely designate it for caterpillar venom only. Do NOT use it for feed or edibles.
Spray them down
Kill the caterpillars with a spritz of rosemary or cedar oil. Use a small bottle and spray them when you see them. They hate these oils. It burns them.
Use Bt
Bacillus thuringiensis is a completely natural and organic bacteria that are very effective in killing caterpillars. You can often find it in your local nursery.
For most Bt, you use it by gently dusting it into the plant leaves throughout the season. The Bt will wipe out the puss caterpillars. Use as directed. Don’t use near butterflies because it’ll kill beneficial species too.
Plant host plants farther from your house
One way to reduce the number of puss moths is to simply plant foliage farther from your household.
Don’t plant them along the edges or landscape zones of your house. Instead, plant them along a fence or other zones that are farther.
If you have shrubs near the entrance of your home or along the walls, remove them. This will significantly reduce long wanderer puss caterpillars coming inside your house.
Remove host plants
If you don’t care for the plants that they’re investing in, remove them entirely.
This will completely get rid of their source of food, so they have no reason to infest your garden anymore. In rural zones, this may not work if they have nowhere else to deposit eggs.
They’ll use your garden’s foliage for feeding or breeding. If you choose to remove host plants, do it in early spring before the flannel moths have a chance to lay eggs in them.
Puss caterpillars will be gone by the spring, so you can also use that period to remove the plants. You want to remove plants when the puss caterpillar population is low or else it’s too dangerous.
Regardless, always use protective equipment. Do NOT assume there are no caterpillars. Look before you reach for plants.
Remove the cocoons
If you come across cocoons hanging off branches in the winter, you can remove them and dispose of them in soapy water to kill the caterpillars.
Use protective gloves because you never know where they could be hidden when you’re reaching out. Then use a pair of tongs to remove the cocoons.
You can prune the entire leaf if you wish. The cocoons should be either soaked into dish detergent or relocated to another part of your property. This way, they’re less likely to intrude.
Use a vacuum
If you have a shop vac, you can use it to vacuum those bugs. Use a disposable bag to quickly get rid of them.
You can put the bag in the sun to kill them. Consider the entire thing to be very contaminated so get rid of it accordingly.
Shop vac makes quick work of caterpillars hiding on the leaves. Wear protective gear and assume the vac to be contained after use.
Keep shrubs and trees trimmed
Foliage that’s left to the elements will become too dense. This can create an environment that puss caterpillars favor.
Clean up your garden by doing the following:
Remove unwanted plants or shrubs
Prune foliage regularly
Remove leaf litter immediately
Don’t overwater or overfeed plants
Ensure water is well draining and doesn’t pool
Keep shrubs trimmed
Mow grass
Clean up grass clippings
Get rid of water features
Doing these basic practices will keep puss caterpillar occurrences low. They love overgrown jungles to hide and feed in. don’t let that be your garden.
Keep your house maintained
If you want to keep puss caterpillars from getting into your house, make sure that your house is well-maintained.
This means using things like weather stripping around windows and blocking under door gaps. Repair holes or cracked siding where they can get in.
Fix damaged foundational cracks or other gaps. This will help keep the caterpillars out.
Neem oil
Sprays that contain neem oil (or just pure extract) are a good way to kill caterpillars.
It also has less impact on beneficial insects or predators. If you choose to use neem oil, dilute it accordingly. Spray in the evening- never in direct sunlight because it can burn your plants.
Wash off excess oils on the leaves. Neem oil kills caterpillars. It also has a residual effect by leaving a coat on the foliage afterward.
Reapply after rain or wind. Some people or pets may be adversely affected by neem, so use as directed. Read all warnings. Neem can be especially harmful to cats or animals that frequent your garden.
How to prevent puss caterpillars
This puss caterpillar may look cute, but NEVER touch it! (By touterse, CC BY 2.0.)
Puss caterpillars are seasonal pests. If you remove their source of food, you reduce the possibility of infestation.
They prefer taller foliage, so if you can remove elm, oak, dogwood, sycamore, cherry, maple, plum, apple, orange, lemon, lime, citrus, etc. from your garden, they may be deterred since there’s nothing to eat.
Unless you care about these plants, remove them. If they just sit there serving no purpose, they host a lot of food for puss caterpillars to consume. No food, no bugs.
Set up an integrated pest management plan
An IPM can help you deal with caterpillars and other similar bugs in general like woolly bears.
Setting up a garden that’s unfavorable to them, strategically placing repellents, and getting rid of existing caterpillars can all contribute to a pest-free garden.
Take steps to discourage moths from settling in your garden. If you keep these guys out then you have no issues with caterpillars.
Physical removal, bringing in natural predators, and using natural repellents is a good combos.
Use natural pesticides as a last resort to kill them and bring their numbers down.
Commercial remedies
If none of the above natural remedies work out for you, consider using pesticides to kill them with synthetics.
If you have a lot of puss caterpillars gobbling up all your foliage, you may want to use a spray to do the job
But if you have edibles, pets, or people that frequent the yard, consider opting for organic insecticides only.
Look for sprays that contain the following compounds that work well for caterpillars:
Lambda-cyhalothrin
Cypermethrin
Permethrin
Bifenthrin
Note that this may harm beneficial pollinators or insects, so only use it as a last resort. Follow the directions on the packaging.
This is an adult puss moth. Notice the similarities in the patterning. (By Ben Sale, CC BY 2.0).
Asp caterpillars are usually harmless and a pleasure to have in the garden since they bring those pretty asp months later on.
Getting rid of them is a risky endeavor because of their venom. Always start with basic techniques first before you move on to the synthetics, but consult with professionals if you don’t know what you’re doing.
Use protective equipment (sleeves, goggles, pants, rubber gloves, broad hat, etc.). Look before you reach into the leaves. They can be hiding just waiting to give you a scare.
Never touch foliage without checking first or using an extended device. Using these natural solutions is preferable for smaller infestations.
Remember that most puss caterpillars are harmless, so you can ignore them if you can. But if not, then try these greener methods before bringing out the sprays.
Currently an active researcher in the pest control industry for the past 8 years- with a focus on using natural and organic methods to eliminate pest problems.
I share handy DIY pest techniques I come across here to help out others (and possibly save them from a mental breakdown).
