This article is a guide on everything that you need to know about the Unicorn Caterpillar.
The unicorn caterpillar is a special species of caterpillar that possess a unique horn-like protrusion that helps it spray its predators with acid.
Smartly camouflaging themselves against half-eaten leaves, these caterpillars are capable of infesting plants and killing them with their voracious feeding spread over the summer months.
Let’s look at these caterpillars and the moths they develop into.
What Are Unicorn Caterpillars?
Coelodasys unicornis, or the unicorn caterpillar, is the larval version of the brown and variegated unicorn caterpillar moth.
They are commonly found in the North American continent and belong to the family of Notodontidae or “prominent moths.”
Earlier, the caterpillar was placed under the genus of Schizura but was shifted to the Coelodasys genus based on papers published in 2021.
What Do Unicorn Caterpillars Look Like?
As larvae, they have a segmented body, with the second and third segments being green. The rest of their body is uniformly brown.
Their name comes from the horn-like protrusion that the larvae have at the head of their first segment.
The eighth segment has another smaller protrusion. Larvae are less than 1.49 inches in length.
The hump can spray a jet of defense liquid consisting of formic acid, which can cause skin irritation and burning.
As adults, they transform into a moth with a mottled or variegated bodies.
The forewing colors may range from maroon to purple, with spots that are rose, yellow, or brown in color.
The hindwings are shades of grey, with females having darker hindwings than males.
The base of their body has a greenish-white color followed by two dark lines. When at rest, adults fold their wings into a tent-like shape.
What Does A Unicorn Caterpillar Eat?
The unicorn caterpillar larvae are voracious eaters. They feed on leaves and leave large, gaping holes, which can eventually weaken and kill the plant.
Larvae feed on deciduous trees like aspen, oak, birch, and other broadleaf plants.
They have to chew mouthparts that help them eat through the leaves.
Their feeding time extends from spring all the way to fall while they overwinter in cocoons.
Adults, on the other hand, have a siphon-like mouth part that allows them to extract nectar.
Adult moths are not harmful to plants and actually help with pollination.
Where Do Unicorn Caterpillars Live?
Their population is distributed throughout North America. they were first discovered by James Edward Smith.
They are found in all the states of the United States and parts of Canada.
They are found in leaf litter and on host plants.
Eggs are laid on the tip or leaf edge of cherry leaves. Both larvae and adults are great camouflagers.
Any deciduous woodlands or shrubbery can contain eggs and larvae.
Life Cycle of A Unicorn Caterpillar
Unicorn caterpillar moths lay leaves on the tip of cherry leaves.
These hatch into caterpillar instars at around May in the South and June in the North.
The caterpillars are shaped to resemble brown dried leaves and have exceptional camouflage against cherry leaves.
They feed on the leaves and go into a white and flimsy cocoon in the fall, usually under leaf litter.
Adult moths emerge from this after the winter. They have approximately one generation per year.
How Long Do Unicorn Caterpillars Live?
Caterpillars can live for many months, with the average larvae feeding on leaves for a period of four months between spring and fall.
Some caterpillar species feed for years, overwintering in multiple pupal stages – however, the unicorn caterpillar undergoes only one.
As adults, their lifespan is comparatively short, with the sole purpose being to find a mate.
While we don’t know exactly how long the unicorn moth survives, most moths have a short lifespan ranging from a few days to a few weeks.
Do They Bite?
A unicorn caterpillar cannot bite, and neither can an adult unicorn moth.
Both do not have biting mouth parts and are more likely to use other defense mechanisms than bite.
However, it’s best not to disturb unicorn caterpillars as they can spray a nasty jet of acid onto your skin.
Are They Poisonous/Venomous?
A unicorn caterpillar can shoot a spray of formic acid from the hornlike protuberance on its body.
This can cause painful blisters on coming in contact with human skin.
While it is not poisonous per se, it is corrosive and causes the skin to burn and sting. It’s best to seek medical advice if you get sprayed on.
Adults do not possess this capability and are hence neither poisonous nor venomous. However, some people are allergic to the powdery residue on moth wings.
Are They Harmful or Beneficial to Humans?
As larvae, the caterpillars can infest gardens and leave large holes in leaves. A group can destroy all leaves in a plant, causing it to die.
However, it’s best to use organic ways such as neem oil rather than insecticides to get rid of them.
Moths are beneficial as they help in pollinating plants.
What Are Unicorn Caterpillars Attracted To?
As adults, the moths are attracted to light. Due to this, they might often end up inside homes.
Larvae, on the other hand, are mostly nocturnal and attracted to host plants that include broadleaf plants and shrubs.
They retire to darker spaces and crevices, such as tree hollows, under rocks, and leaf litter.
How To Get Rid of Unicorn Caterpillars?
Some common methods of getting rid of unicorn caterpillars are:
If they are few in number, you can simply pluck them off and kill them in soapy water or place them elsewhere.
Remember to do this while wearing appropriate gear on your face and hands to protect yourself from their defense spray.
Try to create a bird bath or feeding zone. This will attract their natural predators and cause a decrease in numbers.
Alternatively, you can try to catch them by laying down a burlap at the base of the tree or on leaf litter.
As the caterpillars go into hiding, they might use the burlap, which you can then get rid of.
Make an organic insecticidal soap spray, or spray your plants with neem oil.
Finally, you can use commercial pesticides. However, these will also harm your plants and other beneficial insects.
Alternatively, you can look for degreed professionals who can help you with infestations.
Interesting Facts About Unicorn Caterpillars
Unicorn caterpillars are geta at camouflaging and are very well-suited to their surroundings.
The green segments, brown markings and dots, and overall shape of the body resemble a fried leaf that is curling at the edges.
It is theorized that the glands in the caterpillar’s body that help them spray formic acid take up almost 1/10th of the space within their body volume.
Adult moths are only 0.7 inches to 0.9 inches in size.
Sometimes, parasitoid wasps will prey on unicorn caterpillars.
The parasite will turn the caterpillar into a zombie version of itself that will then guard the wasp eggs and finally turn into food for the larvae.
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Frequently Asked Questions
What does a unicorn caterpillar turn into?
Unicorn caterpillars turn into unicorn caterpillar moths.
There are two varieties of these moths: unicorn prominent or variegated prominent.
These names come from the bodies of the adults: the prominent ones are mottled, whereas the variegated are true to their name.
What do unicorn caterpillars eat?
Unicorn caterpillars mainly eat leaves from willow and cottonwood trees.
These caterpillars feed on the leaves of the tree throughout their larval stage, slowly munching away until it is ready for their transformation.
As adults, unicorn caterpillars feed off of nectar from flowers found nearby to its host tree.
It is important to note that adults rarely return to feed on the willow or cottonwood trees after their metamorphosis.
Why do caterpillars form a circle?
Caterpillars form a circle when they need to rest or sleep.
By forming a circle, they are able to protect themselves from potential predators.
As an additional protection measure, the caterpillars link their tails together to form a tight knot that is difficult for predators to penetrate.
Furthermore, the caterpillars’ circle formation helps them stay warm during the night by creating a buffer around them of their own body heat.
What animal kills caterpillars?
The primary predators of caterpillars are birds, who often choose to eat them as part of their regular diet.
Other insectivorous animals, such as many mammals, amphibians, reptiles, and spiders, also consume caterpillars.
Especially wasps and ants that are attracted by the pheromones produced by the caterpillar’s body can kill a large number of them in a short amount of time.
In addition, parasitic fungi infect dormant caterpillars and eventually kill them when they awake from dormancy.
Wrap Up
Little research has been done on these caterpillars, and much is unknown about their habits and growth.
However, we do know that while they’re highly beneficial as moths, it’s best to remove unicorn caterpillars from a garden, as they pose a risk to children and pests.
Caterpillars are an essential part of the pollinating ecosystem, and hence, try to transfer them instead of disposing of them.
You can also keep them in a closed indoor terrarium to observe their growth.
Thank you for reading.
8 Comments. Leave new
Does this false unicorn caterpillar turn into a butterfly?
No. It will metamorphose into a Prominent Moth.
Will this false unicorn caterpillar hurt my red bud tree in any way?? What can I use to rid the tree of these?
Will this false unicorn caterpillar hurt my red bud tree in any way?? What can I use to rid the tree of these??
Caterpillars generally do not do lasting harm to trees unless the caterpillars are so numerous as to defoliate an already weakened tree. We do not provide extermination advice.
I found this same catepillar eating the leaves of my bruce apple tree and blue berry bush in Gretna Louisiana zone 9B
Is the unicorn catepillar harmful to people
It is harmless to people.