Types of Inchworms: A Friendly Guide to Identifying Your Tiny Crawlers

Inchworms are fascinating creatures that you may have encountered in your garden or while exploring nature. These tiny, caterpillar-like animals are actually the larvae of certain species of Geometer moths. As they move, they resemble an inch-long worm, giving them their name. However, there are different types of inchworms that you may come across.

Each type of inchworm has unique characteristics, allowing them to adapt to their specific environment. Some inchworms are known for their striking colors, while others blend in effortlessly with their surroundings. By taking a closer look, you’ll be able to appreciate the diversity of these fascinating creatures in nature.

Throughout this article, we will explore the different types of inchworms, their features, and the important roles they play in our ecosystem. So, get ready to dive into the captivating world of inchworms and learn more about these amazing creatures.

Understanding Inchworms

Inchworms, also known as measuring worms, are members of the Geometridae family of moths. These interesting creatures are recognizable by their slender bodies and unique means of movement. They typically feed on a variety of ornamentals, deciduous trees, and shrubs which can be impacted by their presence. Here’s what you need to know about inchworms:

These little creatures have an unusual way of moving. Inchworms use a looping motion, which involves extending their bodies forward and then pulling their rear ends up. This method is not only fascinating to watch but also helps them navigate their environments effectively.

Some distinct features of inchworms include:

  • Slender bodies with few or no hair-like projections (setae).
  • Distinctive prolegs near the rear end, used for movement.
  • Belonging to the Geometridae family of moths, consisting of various species.

An interesting fact about these creatures is that their scientific name, Geometridae, refers to their peculiar way of moving. The word “Geometridae” is derived from Greek words that mean “earth-measuring” – quite fitting for a creature named the inchworm!

Now that you have a basic understanding of inchworms, it’s a good idea to be aware of their presence in your garden or yard. Keep an eye out for these fascinating creatures, and remember, inchworms are just one diverse member of the moth family with their own unique characteristics and movement!

Common Types of Inchworms

Geometer Moth

The Geometer Moth, also known as the Alsophila pometaria, is a species of inchworm that belongs to the Geometridae family. These inchworms are:

  • Known for their distinctive looping movement
  • Found in various colors, such as green, brown, and gray
  • Generally harmless to plants and trees

Cabbage Looper

The Cabbage Looper, or Trichoplusia ni, is a common pest in vegetable gardens. They are:

  • Green with a white stripe down each side
  • Known to feed on a variety of plants, including cabbage, kale, and broccoli
  • Capable of causing extensive damage if left unchecked

Elm Spanworm

The Elm Spanworm, also known as the Ennomos subsignaria, is an inchworm species that feeds on the leaves of elm and oak trees. They can cause serious defoliation in large populations.

Bruce Spanworm

The Bruce Spanworm or Operophtera bruceata, is closely related to the Elm Spanworm. They feed on a wide range of deciduous trees, including oak, elm, and maple.

Hemlock Looper

The Hemlock Looper, Lambdina fiscellaria, is a species of inchworm that feeds on coniferous trees, such as hemlocks, firs, and spruces. They can cause significant damage and defoliation to their host trees.

Alfalfa Looper

The Alfalfa Looper, Autographa californica, is an inchworm that feeds on alfalfa and other legume plants. These pests can cause considerable damage to agricultural crops.

Linden Looper

The Linden Looper, Sabulodes aegrotata, is an inchworm species that feeds on linden trees and is occasionally found on other deciduous trees. They are:

  • Green with white lines on their sides
  • Capable of causing defoliation if present in large numbers

Omnivorous Looper

The Omnivorous Looper, large moth worms, can cause damage to a wide range of plants, from fruits and vegetables to ornamental plants. They are:

  • Creamy white or light green with darker stripes
  • Able to consume many different types of plants, making them a difficult pest to control

Physical Characteristics

Color and Patterns

Inchworms come in various colors and patterns, making them interesting to observe. You’ll commonly find them in shades of green and brown, which helps them blend into their surroundings. Different species might also have spots or stripes on their bodies in colors like black or gray.

Their colors and patterns serve as a form of camouflage, protecting them against predators. For example, some inchworms mimic twigs or leaves, making it difficult to spot them on plants.

Size

Inchworms vary in size depending on the species. Most of them measure between 1/4 and 1 inch in length. Remember, their size can change as they grow, so younger inchworms may be smaller than their adult counterparts.

Head

The head of an inchworm is typically smooth and small compared to its body. It also features lines or markings that help in distinguishing different species. These markings on the head are important for identifying various inchworm species and understanding their individual behaviors and habitats.

Behavior and Habitat

Movement

Loopers, commonly known as inchworms, have a unique way of moving. Instead of walking like other caterpillars, they loop their bodies to travel from one place to another. They do this by:

  • Anchoring their hind legs firmly on a surface
  • Bending their bodies to bring their front legs closer
  • Gripping the surface with their front legs
  • Stretching their bodies forward and repeating the cycle

This mode of travel allows them to move smoothly on various surfaces while remaining inconspicuous.

Camouflage

Inchworms exhibit excellent camouflage abilities to blend in with their surroundings. Their green or brown coloration helps them mimic twigs, leaves, or stems, making them difficult to spot by predators. Some inchworms even have markings that resemble leaf veins or bark patterns.

Habitat

Loopers or inchworms are native to North America and can be found in diverse habitats, such as:

  • Deciduous forests
  • Coniferous forests
  • Meadows
  • Gardens

But they primarily feed on native trees and shrubs, such as rhododendron. The type of habitat they prefer often depends on their specific diet, with some species feeding exclusively on conifers, while others prefer deciduous trees and shrubs.

Remember, as you encounter inchworms in your daily life, appreciate their unique movement, incredible camouflage abilities, and the various habitats they call home.

Life Cycle of Inchworms

Eggs

Inchworms start their life cycle as eggs. Female moths lay small, round eggs on the undersides of leaves during spring or fall. These eggs are often well-hidden and can be difficult to spot. They usually hatch within a week or two, depending on the temperature and environmental conditions.

Larvae

Once the eggs hatch, the inchworm larvae emerge. These caterpillars are known for their distinctive “looping” motion and can be found in various colors, such as yellow-green, brownish, blackish or green. Some species even have a white stripe running along the side of their body (source). The larvae mainly feed on deciduous trees and shrubs, with some species exclusive to conifers or other types of plants (source). Throughout their larval stage, inchworms go through multiple growth stages called instars, shedding their skin and growing larger each time.

Here are some characteristics of inchworm larvae:

  • Distinctive looping motion
  • Various colors and markings
  • Feed mainly on tree leaves and shrubs

As the larvae grow, they eventually reach a stage where they are ready to pupate and transition to adult moths.

Adult Moths

Inchworms complete their life cycle by transforming into adult moths. They pupate in the soil or in crevices on tree bark. During this stage, a protective cocoon is formed around the larva. Pupation can last anywhere from a few weeks to several months, and in some cases, the pupa may overwinter (source).

The adult moths that emerge have a brownish-gray color. Female moths are wingless, while male moths have wings (source). The primary goal of adult moths is to mate and lay eggs, starting the life cycle of inchworms all over again.

To recap, the life cycle of inchworms includes these stages:

  1. Eggs are laid on the underside of leaves
  2. Larvae (caterpillars) hatch and feed on plants
  3. Larvae pupate, forming a cocoon
  4. Adult moths emerge, and the cycle begins anew

By understanding the life cycle of inchworms, you can better appreciate the fascinating world of these unique insects and their role in the ecosystem.

Diet and Feeding Habits

Inchworms, also known as loopers or geometer moths, are small caterpillars typically found feeding on leaves and foliage. These creatures have a unique way of locomotion, where they fold their bodies in half to inch their way across branches and leaves. Let’s explore their diet and feeding habits.

Inchworms are primarily herbivores, with their diet consisting of leaves from various plants and trees. They are not picky eaters and feed on a diverse range of foliage, such as:

  • Fruit trees (like apple or cherry)
  • Shade trees (like oak or maple)
  • Shrubs (like azalea or rose)

These caterpillars are known to feed on both the upper and lower surfaces of leaves, munching away until only the veins remain. Their food preferences depend on their species, and some prefer evergreen foliage or deciduous plants.

Some inchworm species act as pests, causing damage to agricultural crops, gardens, and ornamental plants. It’s essential to monitor their populations and implement control measures if needed, such as natural predators or organic insecticides.

Remember, inchworms are not all bad; they have a role to play in nature’s balance. They serve as a food source for birds and other small animals, contributing to the circle of life in your backyard or garden. So, the next time you spot an inchworm inching its way through your plants, take a moment to observe its fascinating diet and feeding habits.

Inchworms and Their Relationship with Plants

Inchworms, also known as measuring worms or spanworms, belong to the family of moths called geometers. They are known to feed on various types of plants like ornamentals, trees, and shrubs. Inchworms can be considered pests when they damage the plants they inhabit, but not all inchworm species are harmful.

Inchworms can be found on deciduous trees, shade trees, elm trees, oak, maple, and various shrubs. They also feed on host plants like flowers and blueberry plants. Some species of inchworms feed exclusively on conifers, while others prefer deciduous trees and shrubs.

When present in large numbers, inchworms can cause significant damage to plants. They can strip leaves from twigs, leaving the plant weakened and vulnerable to diseases. Your garden plants may suffer from defoliation and reduced growth, as a result.

There are numerous ways you can protect your plants from the harmful effects of inchworms. Consider implementing methods like:

  • Regular monitoring of your plants to detect early signs of inchworm infestation
  • Attracting natural predators like birds, spiders, or parasitic wasps into your garden
  • Using eco-friendly pesticides and insecticides when necessary

As a garden caretaker, it’s essential to be aware of the relationship between inchworms and their host plants. By being vigilant and proactive, you can enjoy a healthy garden free from damage caused by these little pests.

Control and Treatment of Inchworms

In order to protect your garden from inchworm infestations, there are a few tips and techniques that could be quite helpful. First, let’s discuss some typical control methods:

  • Biological control: One natural way to control inchworms is by encouraging the presence of their natural predators, such as birds, parasitic wasps, and beneficial insects like ladybugs. You can attract these predators by planting flowers and shrubs that they enjoy.

  • Manual removal: Check your plants regularly, and if you find inchworms, simply remove them by hand. Dropping them into a bucket of soapy water will ensure they don’t return.

  • Barriers: You can use physical barriers like cardboard collars or aluminum foil wrapped around the trunk of your plants. This helps prevent the inchworms from climbing up and reaching the foliage.

When these prevention methods are not enough, it’s time to consider different treatments available. Among the most common are insecticides and organic pesticides.

Insecticides

Insecticide Pros Cons
Synthetic pyrethroids (e.g., bifenthrin) Effective, broad-spectrum treatment Not environmentally friendly, can harm beneficial insects
Bacillus thuringiensis (Bt) Environmentally friendly, specific to caterpillars Requires multiple applications, less effective on more mature inchworms

Organic Pesticides

Organic Pesticide Pros Cons
Neem oil Natural, biodegradable, less toxic May require multiple applications, could harm some beneficial insects when sprayed

When choosing a treatment method, it’s essential to consider the specific needs of your garden, as well as the potential impact on the surrounding environment. By implementing a combination of these control and treatment methods, you can effectively manage inchworm infestations, ensuring a healthy, thriving garden.

Predators of Inchworms

Inchworms, also known as measuring worms or spanworms, are small caterpillars that belong to the family of moths called geometers. They are known for their peculiar looping mode of locomotion and can be found on a variety of plants, including ornamentals and native trees and shrubs 1. There are several predators that help control inchworm populations in their natural habitat, including birds, spiders, and other insects.

Birds are among the most common predators of inchworms. You’ll often find different species of songbirds, such as warblers, robins, and chickadees, feasting on these small caterpillars. Not only are these birds effective in controlling inchworm populations, but they also help in maintaining a balanced ecosystem.

Spiders too, play a crucial role in keeping a check on the number of inchworms. Various species of spiders, like the orb-weaving spiders and wolf spiders, are known to prey on inchworms. Since spiders use their webs to capture their prey, inchworms that venture too close to these webs often end up as a tasty meal.

True legs, as featured in many predators, aid in their mobility and hunting prowess. For example, some ground beetles possess true legs that enable them to chase and capture inchworms efficiently. These beetles move quickly on the ground, making them capable hunters and powerful predators for multiple insects, including inchworms.

Here are a few examples of inchworm predators:

  • Birds: warblers, robins, chickadees
  • Spiders: orb-weaving spiders, wolf spiders
  • Beetles: ground beetles with true legs

Birds, spiders, and true-legged beetles are essential components of a healthy ecosystem as they help maintain insect populations like inchworms within manageable levels. Protecting and supporting these predators in their natural habitats is a crucial step toward keeping a balanced ecosystem and safeguarding our environment.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Unknown Pink Inchworm

 

Pink Caterpillar
July 18, 2009
This tiny pink caterpillar moved in inchworm fashion and was particularly interested in the pollen/nectar of my Coreopsis flower. About 3/8″ in length, really tiny.
sankax
Minneapolis, MN

Unknown Pink Inchworm
Unknown Pink Inchworm

Dear sankax,
While we cannot tell you the species, this Inchworm or Spanworm is the caterpillar of a moth in the family Geometridae.

Letter 2 – Unknown Australian Spanworm is Pink Bellied Moth Caterpillar

 

Happy new year. 2 queries please, the spider had immobilised the bee, is that its tongue sticking out and what do bees use such a large tongue for? The caterpillar is on a flowering gum in my garden in Queensland and i wondered if you could identify it for me. Thanking you,
dawn lewis

Hi Dawn,
Bees have long tongues to lap up nectar from plants. Your caterpillar seems to be some species of Inch Worm or Spanworm in the family Geometridae. We found an awesome webpage of Australian Geometridae, but had no luck identifying your caterpillar exactly. Caterpillars in this family are also known as Loopers, Measuring Worms and Twig Caterpillars.

Update: (01/04/2008) Unknown owlet moth from Australia
Dear Daniel,
Going on my own observations, it looks very much like the caterpillar of the Hakea or Pink-bellied Moth, Oenochroma vinaria, posted on WTB on 11/11/07. The caterpillar has small white dots over its body and also some yellow larger dots along the back. There are two “horns” just behind the head. When disturbed, the caterpillar rears up, showing its horns more clearly. When at rest, it is well camouflaged, looking just like a brown stick. And a Happy New Year to you and all WTB readers, also.
Grev

Letter 3 – Spanworms dropping from Trees in Texas

 

Subject: Worms
Location: Denison tx
April 6, 2015 5:34 pm
We have zillions of little worms hanging from Cobb webs out of the tree and the porches. Really everywhere. What r they and what can we do about them?
Signature: Michelle

Spanworms
Spanworms

Dear Michelle,
In the past, we have gotten reports of Oak Leafroller Caterpillars,
Argyrotaenia quercifoliana, hanging from trees, but a closeup of your caterpillars indicates they are a different species in the Spanworm or Inchworm family Geometridae.  We will research this and try to come up with a species identification for you.

Spanworms
Spanworms
Spanworms
Spanworms

They are killing my trees I think and I’m not sure what to do.  Parts of my trees are brown where they were budding leaves last week

Newly Planted Apple Tree, we presume.
Newly Planted Apple Tree, we presume.

Hi again Michelle,
One tree image you provided appears to be a freshly planted Apple Tree.  Please provide information on the tree.  What is it?  When was it planted?  Is this the only place you are finding the caterpillars?  It is possible the eggs were on the tree when it was purchased and now that all the young leaves have been eaten, the caterpillars are on the move searching for more food.  If their diet is limited to the leaves of apple trees, they will starve and you will no longer have the caterpillars, and unless the tree is really unhealthy, new leaves will sprout.  We just noticed you also attached an image of a large tree.  What kind of tree is it?  Are the caterpillars on all of your trees or only on selected trees?  The large tree should have no trouble resprouting if it is an otherwise healthy tree.  Birds and other insectivore predators should help to keep the numbers of caterpillars in check.

What Tree is it?
What Tree is it?

 

Letter 4 – Unknown Arizona Caterpillar: Meris paradoxa

 

Unknown caterpillar – Flagstaff, AZ, U.S.A.
Hello,
I am hopeful that you’ll be able to help me with the caterpillar in the attached photos. These were taken on April 26, 2008 in my yard in Flagstaff, AZ, U.S. Flagstaff is in the mountains of Arizona at an elevation of about 7000 feet (a bit over 2130 meters – I think). After perusing your letters on caterpillars (I am amazed at your knowledge), I am wondering if it is an early instar of a Parnassian species? However, my “Butterflies of Arizona” does not list any Parnassians. And, while the National Audubon “Field Guide to North American Butterflies” does list a few, the descriptions of the caterpillars don’t seem to match. This particular caterpillar appears to be white with black, longitudinal stripes, and yellow spots along the sides. It was on a Penstemon, which is listed (in the Audubon book) as a host plant for the Arachne Checkerspot, but the caterpillar description doesn’t seem to match up. I’m at a bit of a loss … Thank you for a wonderful site, and thank you in advance for any assistance.
John Ellison,
Flagstaff, AZ, U.S.A

Hi John,
We have to come clean and say we just don’t know for sure. Based on the absence of most typical pairs of prolegs, we believe this is a Spanworm or Inchworm in the family Geometridae, but we cannot locate a good match on BugGuide.

Update May 25, 2014:  Meris paradoxa
Thanks to an identification request we received today, we were able to identify the new request as well as the long unidentified posting from our archives as
Meris paradoxa, an Inchworm with no common name.

 

Letter 5 – Unknown Caterpillar from Botswana is Dice Moth Caterpillar

 

Very abundant inch worm in Kasane, Botswana
Location: Kasane, Botswana
January 14, 2011 4:58 pm
I have seen this inch worm several times around my home in Kasane, Botswana. Right now it is the rainy season and is the only time I have seen this worm. It is very colorful and has almost feather like spikes. I did handle it and it was not poisonous. Do you know what this bug is or what it will become. It is very beautiful.
Signature: Laura Marchitto Massie

Dice Moth Caterpillar

Dear Laura,
We are not entirely convinced that this is an Inchworm, a name along with Spanworm given to the caterpillars of moths in the family Geometridae because of the way that they crawl.  According to Bugguide:  “larvae generally have only two pairs of prolegs (at the hind end) rather than the usual five pairs in most lepidoptera; the lack of prolegs in the middle of the body necessitates the peculiar method of locomtion, drawing the hind end up to the thoracic legs to form a loop, and then extending the body forward.
”  The caterpillar in your photo has three pairs of prolegs, which is fewer than the five possessed by most caterpillars, hence its method of locomotion.  BugGuide only indicates that “larvae generally have only two pairs of prolegs” which might mean that some individuals have three pairs.  Your caterpillar also reminds us of that of the North American Funerary Dagger Moth which is depicted on BugGuide.  We will attempt to get you a species identification, and until we determine otherwise, we will archive your letter with the Inchworms.  Perhaps we can enlist assistance from our readership towards a conclusive identification of this interesting caterpillar.

 

Letter 6 – Unknown Caterpillar from Cyprus is Apochima flabellaria

 

Subject: catterpillar
Location: Cyprus
November 18, 2012 2:30 am
i took this a while ago in Cyprus which is an island in the Mediterranean and i cannot identify it but am curious.
Signature: tatiana h

Apochima flabellaria Caterpillar

Dear Tatiana,
We have already spent some time this morning in an attempt to identify the three different caterpillars from Cyprus that you have requested assistance with identifying, but we haven’t had any luck.  This spiny caterpillar has us most curious.  It appears to have only two legs like the Inchworms or Measuring Worms in the moth family Geometridae, but we are not convinced it even belongs in that family.  We thought a caterpillar this distinctive would be easier to identify, but alas, we have come up blank.  Can you provide any additional information?  Your photos indicate you found at least two individuals.  Were they found on any particular plant?

Apochima flabellaria Caterpillar

One photo has them in the sand.  The photos also indicate that they curl into a ball for protection and the spines would keep them from being swallowed by predators such as birds.  None on your caterpillars are represented on this Insects of Cyprussite we found.  We are relatively certain that this is the caterpillar of a moth and that it might be in the family Geometridae.  Perhaps one of our readers will have better luck with an identification. 

Unknown Caterpillars

Update:  November 18, 2012
Thanks to a comment from Ben from Israel, we now know that this is
Apochima flabellaria, a member of the family Geometridae that Ben says is commonly called the Mediterranean Brindled Beauty, a name that is used on European Butterflies and Moths.  We did find images of the caterpillar on TrekNature and Lepidoptera Pro.

 

Letter 7 – Unknown Spanworm from Australia

 

Very, very tiny black caterpillar with white spots
February 8, 2010
‘Ello Bugman!
Today I found a very, very tiny black caterpillar. He’s approx 3mm long and has tiny white spots which first I thought were stripes across his body.
I live in Australia in NSW and it is currently Summer (although has been wet and rainy for a week now).
I don’t know what the plant is. It self-seeded from somewhere and I don’t mind if he eats it all up.
It would be interesting however, to find out what he is, how big he will get and what he is to become.
Thanks!
Bronwyn
Penrith (Western Sydney, NSW Australia)

unknown Inchworm from Australia

Hi Bronwyn,
We can say for certain that this is a Spanworm or Inchworm caterpillar in the family Geometridae, but we would need additional time to determine the species.  Since it is so small, it is an early instar, and it may undergo five additional molts before pupating.  Each molt or instar may have different markings and coloration.  Generally, most caterpillar photos are of the final instar, and it can be quite difficult to properly identify the earlier instars.  Knowing the food plant often helps, but alas, we do not recognize your plant.  As the caterpillar grows, molts and changes, you may send additional images in the hope that would assist in identification.

Host Plant

Letter 8 – Winter Moth Larvae

 

Thought you’d like these pix of winter moth larvae (Operophtera brumata)
Sun, May 17, 2009 at 3:58 PM
Here in eastern Massachusetts we are having a horrible infestation of winter moths for the 3rd or 4th year. Each year they get worse, and the damage to the trees around here is greater and greater. I know that you think that there’s no such thing as a bad bug, but I’m having a hard time finding good in these guys. My car is covered in their feces and the driveway has a thick slippery coating of caterpillar poop.
Anyway, we had a rain last night and quite a few got knocked out of the trees and took refuge under our cars. Not sure why they all huddled together, perhaps for warmth. It was not a pretty site when I backed the car out of the driveway…
G. Glater
Natick, MA

Winter Moth Caterpillars
Winter Moth Caterpillars

Dear G.,
We needed to do a bit of research on the Winter Moth.  BugGuide hasn’t much information on the species, and indicates of the genus:  “small geometers with banded brown forewings and plain whitish hindwings. Range southern Canada and northern United States (extends further south in the Appalachians and Rockies) ”  BugGuide has no images of the caterpillars.  The Massachusetts Department of Agricultural Resources Introduced Insects Page indicates:  “Adult moths emerge in late November and can be active into January  under the right weather conditions.”  The University of Massachusetts Green Info page has a pdf on the winter_moth that indicates the species was introduced from Europe.  In its own natural habitat, the Winter Moth Caterpillars probably have natural predators that feed upon them.  It is also possible that in Europe, there are periodic outbreaks that result in a necessary food source for other animals.  Thanks for sending your awesome images of this outbreak of an introduced invasive exotic species.

Winter Moth Caterpillars
Winter Moth Caterpillars


Letter 9 – Woolly Gray Spanworm

 

Subject: 2 catepillars
Location: Needville, TX
April 20, 2014 8:42 pm
found these 2 in a park brazos bend park. Curious to know what they are.
Signature: CC

Woolly Gray Spanworm
Woolly Gray Spanworm

Dear CC,
We are splitting your identification request into two distinct postings to better conform to our categorization.  Your first caterpillar, the Inchworm, is a Woolly Gray Spanworm,
Lycia ypsilon, which we quickly identified on BugGuide where it is noted:  “One of only a handful of brightly colored inchworms in the East.”  This is a new species for our archives.

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

5 thoughts on “Types of Inchworms: A Friendly Guide to Identifying Your Tiny Crawlers”

  1. I just found one of these. I see green ones, floating around on their silk all the time. But today is the first time I have ever seen a red one floating down to the ground on a strand of silk. I love to catch the inch worms. But was afraid to touch the red one. LOL

    Reply

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