Underwing moths are fascinatingly beautiful creatures, but what about their caterpillars? Are underwing caterpillars equally rich in colors and variety? Find out all this and more below!
Underwing moths carry quite a unique appearance due to the heavily contrasting colors of their wings. However, they also happen to be plant-eating pests.
Regardless of whether you’re here simply because you love learning about different insect species or to know whether underwing caterpillars pose a threat to your plants, you’re going to find this article helpful.
What Are Underwing Caterpillars?
Underwing caterpillars are the larvae of underwing moths – a type of moth that has bright hindwings hidden under dull-colored forewings.
Growing up to an inch long, these worms feature prominent circular markings on their bodies.
One can divide the body of an underwing caterpillar into four distinct segments – the lobe, the horn, the saddle, and the ridge.
While their overall appearance doesn’t look very different from most caterpillars, certain species have unique features such as a fake head or special camouflaging abilities.
These worms are also classified as cutworms due to their tendency to chew through the stems of seedlings and plants, thereby cutting them up.
Why Are They Called Underwing Caterpillars?
Underwing moths get their name from their unusual set of wings. The hindwings of underwing moths lie concealed under their forewings when not in flight.
While the forewings are usually rather dull with pastel colors like brown and grey, their hindwings tend to be bright and colorful, like a butterfly.
Usually, as long as the moth is sitting, we only get to see the dull forewings. The dull forewings of the underwing moth also allow it to stay camouflaged on tree trunks and branches.
But when attacked by a predator or taking flight, they will throw a curveball.
They unveil their bright and colorful wings, which momentarily blind their predators and give them the few crucial milliseconds extra that save the moth.
Types of Underwing Caterpillars
You might want to note that the term ‘underwing moths’ does not refer to a single species.
Scientifically known as Catocala, it’s an entire genus of Holarctic moths belonging to the Erebidae family.
Some of the most common types of underwing moths are
Large yellow underwing
These large moths are quite widespread, but they aren’t native to North America.
They entered the continent through Nova Scotia, from where they spread to Wyoming, California, Ontario, British Columbia, Vermont, New York, etc.
The moth features bright orange-yellow underwings and forewings that range from light brown to almost black.
Large yellow underwing larvae can be green or brown, with two black dashes along the rear.
This cutworm is a major garden pest and can cause fatal damage to different herbaceous plant species.
Oldwife underwing
The oldwife underwing caterpillar has a grey and brown body and an ivory-colored head.
This caterpillar has tiny bumps all over–white bumps near the head, orange bumps on the body, and white dark ones near the rear end.
Additionally, they also feature a fringe of hair by the legs. The adult moths have rich orange underwings with black bands.
Their grey forewings are crossed by scalloped black lines.
In the US, you can find this species in South Carolina, Maine, Tennessee, New Jersey, Iowa, Illinois, Michigan, Indiana, Oklahoma, and Arkansas.
Copper underwing
Although its name indicates otherwise, the copper underwing doesn’t belong to the same family as the underwing moths.
While it does have dull grey forewings and bright hindwings, the thick black band found on the hindwings of underwing moths is missing in this species.
Instead, the Copper underwing belongs to the Amphipyrine Sallow family. Their pale green larvae have small bumps around the rear end.
They feed on the foliage of a variety of plants and trees, ranging from grape vines and Virginia creeper to Oak, maple, and birch.
Pink Underwing
This underwing species deserves special mention due to the unique appearance of the caterpillar.
Pink underwing caterpillars have a large fake head, with two large eyespots and a pattern made of white markings.
Have a look for yourself!
It uses its scary appearance for natural protection, deterring predators by revealing large eyespots and white markings when threatened.
The adults have dark brown-black hindwings with a patch of pink that extends to the inner markings.
Their brown-grey leaf-shaped forewings allow them to camouflage themselves as dry leaves.
Other Underwing caterpillar species, like the tearful underwing and the darling underwing, are also quite common in North America.
Where Do They Live?
Underwing caterpillars can be found all over the world, although the species differ from one region to another.
They’re very common in the US, and there’s a good chance that you might find them munching on your garden plants.
These moths and caterpillars can live in almost every habitat, although you’re most likely to find them in and at the borders of deciduous forests.
They’re very common in subtropical rainforest regions, especially among rainforest vines.
Underwings are active at night, feeding in the tree canopies. During the day, they stay hidden in crevices or camouflaged against tree trunks.
What Do They Eat?
Underwing caterpillars and moths both feed on a variety of plants and trees, especially deciduous ones.
The caterpillars are known to be fond of feeding on the leaves of wooded trees and shrubs. However, they also attack ornamental plants and other garden plants with soft stems.
They cause heavy damage by chewing through the stems and the branches, which can sometimes be fatal for the plants.
A variety of herbaceous plants and grasses are prone to damage from underwing caterpillars.
What is the Lifecycle of an Underwing Caterpillar?
The lifecycle of an underwing caterpillar is very similar to other moth species – they spend the larval stage as hairy caterpillars and later pupate into winged adults.
They’re single-brooded, i.e., they produce only one generation a year. Let’s take a more detailed look at their life cycle:
Eggs
Unlike many other moths that spend the winter hibernating as larvae or pupae, underwing caterpillars overwinter as eggs.
Their spherical eggs are initially pale yellow but darken a bit as they age.
The adult females lay them singly or in clusters, usually under leaves of plants in overgrown areas to keep them concealed or on the bark of trees.
Larvae
The eggs hatch in spring, releasing the larvae just as new foliage starts to emerge on the trees. Underwing caterpillars may be flat or flat or cylindrical, depending on the species.
They have a bark-like mottled appearance to them, with warts and bumps on the dorsal side.
Like most caterpillars, they grow very fast and undergo several molts. Like the adult moths, they’re nocturnal too and feed on tree leaves and soft plants.
Pupae
Once the underwing caterpillars are mature, they pupate. Caterpillars undergo a thorough metamorphosis during pupation, getting a completely different appearance from adult moths.
Adult
Finally, moths with dull forewings and bright hindwings emerge from the pupa at the end of the transformation.
They develop an average wingspan of 1.9 to 3.1 inches. They continue their nighttime habit of feeding on leaves, mating, and laying eggs early into the winter.
The eggs hatch later in spring, and the entire cycle repeats.
Do They Bite or Sting Humans?
You don’t have to worry about getting stung or bitten by underwings, be it the moths or caterpillars.
While underwing caterpillars can chew through leaves and soft stems, their mouthparts are not suitable for biting humans.
When they feel threatened, they simply curl up into a C-shape like many other caterpillars.
Are They Poisonous or Venomous?
When it comes to caterpillars, poison or venom can sometimes be a concern. Some species of caterpillars are dangerous to handle as they’re venomous and can even cause death.
Thankfully, this doesn’t apply to underwing caterpillars. They are all non-venomous, and you can remove them by hand without any worries.
Are They Harmful to Humans as Pests?
While underwings don’t hurt humans directly, they can be a serious pest. Caterpillars tend to be voracious eaters, and underwings are no exception either.
They consume large amounts of plant matter in short periods, eating through leaves, branches, stems, and even roots.
The moths have similar feeding habits, but they’re in a state of feeding frenzy during the larval stage.
An infestation of underwing caterpillars can cause severe damage to your garden or houseplants.
Underwing moths flying around your garden are a beautiful sight, but you may need to get rid of them to protect your plants.
Are They Beneficial?
Underwing caterpillars and moths aren’t exactly beneficial to humans. This doesn’t necessarily mean they shouldn’t exist – every species has a role to play in the ecosystem.
However, underwings do more harm than good in gardens, and it’s best not to let them hang around on your property.
How To Get Rid of Them?
Thankfully, eliminating underwings from your garden isn’t too hard and there are several ways to go about it:
Natural predators
The best way to control garden pests is to maintain a balanced ecosystem and draw in potential predators. The underwing caterpillar has various natural enemies, ranging from spiders and parasitic wasps to birds and rodents.
Manual removal
As underwing caterpillars are non-venomous and do not bite, you can simply pick them off the plants and remove them.
Diatomaceous earth
Sprinkling Diatomaceous earth over the leaves and on the soil surrounding your plants is a great way to keep cutworms from damaging them.
Biological control
Watering the soil with beneficial nematodes and other insecticidal bacteria like Bacillus thuringiensis can kill the larvae too.
Frequently Asked Questions
Is the red underwing moth rare?
The red underwing moth isn’t rare and happens to be quite common. However, these moths might seem rare in North America as they’re mostly found in England and Wales.
With a wingspan of 3.5 inches, it also happens to be one of the largest species of moths in the UK.
Is the large yellow underwing invasive?
The large yellow underwing is an invasive species in North America. It’s native to Europe but has spread pretty much all over the world.
These underwings have grown abundantly in North America since their first appearance in Nova Scotia.
How big are underwing moths?
Underwing moths are quite big and heavy, and in many cases, among the largest moths in a region.
They usually have a wingspan between 1.9 inches and 3.1 inches, but some species can be even larger. During the larval stage, they are about an inch long.
What does a pink underwing moth look like?
The pink underwing moth (Phyllodes imperialis) looks a lot like dry leaves, which is perfect for camouflage.
They even have leaf-shaped brown forewings that help them with the resemblance. Their dark brown hindwings have a pink patch each that extends to the inner margin.
Wrap Up
As it turns out, underwings are major pests regardless of how beautiful the moths might look while flying around.
Keep an eye out for these moths and caterpillars in your garden, and get rid of them at the earliest.
In the event of a major infestation, it won’t take them long to wreak havoc on your beloved plants.
With that, I conclude this article and hope that you have found it helpful.
Reader Emails
Underwing caterpillars are just as fascinating as they are harmful to garden crops.
Many of our readers have shared with us pictures of these bugs with SOS messages on what they are and how to get rid of them (because they are feeding away at the plants!).
Please go through a selection of some of these emails and also learn about some of the ways in which people have been dealing with them.
Letter 1 – Ilia Underwing Caterpillar
Caterpillar found by oak tree
May 30, 2010
The of this caterpillar I took when I found it on my drivway which has large oaks on either side of it. I can not find its piture in any of my insect books.
Bill L.
Kennebunk, ME
Letter 2 – Underwing Caterpillar
Caterpillar identification in Georgia
Location: Jackson, Georgia
April 8, 2011 9:01 am
Hi there, love your site!
I live in central Georgia, about midway between Atlanta and Macon. This little fella has been making his way across my deck for the past several days, and I’m fascinated (and becoming somewhat attached to it, I admit). I’ve searched your site pretty thoroughly, and can’t find anything resembling it. He’s very ”scaly” in appearance, about 2.5” long, and he moves so imperceptibly/slowly that I can’t really tell if you’d consider him an spanworm or not. Picture was taken by me this morning, April 8, 2011. Thanks so much!
Signature: Alex
Letter 3 – Underwing Caterpillar
Subject: Caterpillar
Location: South Texas
March 28, 2016 5:58 pm
I live in south Texas. We lots of large oak trees. Found these caterpillars under the dead leaves on the ground. What kind of caterpillar is it? And should I be worried
Signature: Luckylisa
Letter 4 – Underwing Caterpillar
Subject: Insect larva?
Location: Port Orchard, WA
November 23, 2016 10:06 pm
I found this critter on a wood fence in my garden on the west side of Puget Sound in western Washington state. I shot the attached picture during August. I tried to chase the i.d. down on the internet, but don’t have enough bug knowledge to find it. I’d love to hear your best guess. Thanks.
Signature: Jim McCausland
Letter 5 – Underwing Caterpillar
Subject: Big caterpillar
Location: Milton, GA (North Georgia)
April 16, 2017 9:38 am
Saw this today in Milton, GA-he has a purplish underbelly. He moves like an inchworm, sort of. He’s pretty aggressive-flopped around as I was trying to get a photo.
Signature: Melinda
I live in south eastern Massachusetts,me and my son found a underwing caterpillar that resembled lichen moss (color and markings) it seemed aggressive for a caterpillar.
Are they aggressive and are they poisnious?
They are not poisonous. Aggression is relative.
I believe my kidos found one out in our back yard. Here in Virginia. I have a picture but cannot load it on here. Where about are they located?