What Do Inchworms Eat: A Quick Guide to Their Diet

Inchworms, also known as measuring worms or spanworms, are fascinating little creatures often found crawling on leaves, munching their way through a variety of plants. As caterpillars, they belong to the family of moths called geometers, which has numerous species with varying preferences in food. It’s essential to understand their diet, as it could affect not only your garden, but also local ecosystems and native trees and shrubs.

These tiny caterpillars are not picky eaters, quite the opposite, they have an extensive menu ranging from ornamentals like rhododendron to deciduous trees and even conifers. Their diet is determined by the specific species they belong to, and it can sometimes be exclusive to a particular plant or tree type. In general, inchworms feed on leaves and foliage, but some may also consume flowers and fruits.

By knowing what inchworms eat, you can be better prepared to manage their populations in your yard or garden, preventing extensive damage to your plants. Furthermore, understanding their eating habits also helps in preserving the natural balance in the environment since these crawlers contribute to the ecosystem as a food source for birds and other predators.

About Inchworms

Inchworms, also known as loopers or measuring worms, are small caterpillars that belong to the Geometridae moth family. With over 1,200 species in North America alone, these fascinating little creatures are quite diverse in their appearance, featuring various colors to blend in with their environment. Some common inchworm characteristics include:

  • Two sets of prolegs, used for their unique movement style
  • Camouflage abilities to hide from predators
  • Most species feed on leaves from trees and shrubs

What makes inchworms stand out is their peculiar way of moving. Instead of crawling like most caterpillars, inchworms move by forming a loop with their body, then extending their front part forward, giving them their well-known name. This looping movement is often a delight to watch as they navigate their environment.

Inchworms have both benefits and drawbacks in their role in the ecosystem. Some pros and cons of inchworms include:

Pros:

  • Act as a food source for predators like birds and small mammals
  • Some species help with pollination

Cons:

  • Can become pests if populations grow too large, causing damage to foliage

When observing inchworms in their natural habitat, remember to stay mindful of your actions, as these small caterpillars can easily be disturbed or harmed. By understanding their fascinating characteristics and movement, you can better appreciate the role they play in the environment and the importance of preserving their valuable ecosystem.

Inchworm Diet

Inchworms, also known as measuring worms, feed primarily on the leaves and foliage of various plants, including trees, shrubs, and garden plants. They have quite a diverse diet and can be found feeding on different trees such as oaks, elms, maples, mulberries, and cherries, as well as on lilac leaves and berry bushes1.

Their diet is not limited to leaves only. They may also consume parts of fruits, flowers, and vegetables. Common garden vegetables they are attracted to include cabbage, cucumber, pears, celery, parsley, beans, Brussels sprouts, cauliflower, potatoes, and other herbs2.

Here’s a quick comparison of the different plants inchworms prefer to feed on:

Leaves Fruits Vegetables Flowers
Oak Apples Cabbage Lilac
Elm Pears Cucumber
Maple Celery
Mulberry Parsley
Cherry Beans

In their natural habitat, inchworms often consume decaying leaves as well3. As herbivores, their diet consists entirely of plant matter, making them a potential nuisance for gardeners who wish to protect their garden plants.

To manage these inchworms in your garden, regular inspection and handpicking can help. You could also introduce natural predators like birds and other beneficial insects to keep their population in check4.

Remember, despite their voracious appetite, inchworms can also play a crucial role in the ecosystem as they help break down plant materials, providing nutrients back to the earth5.

Inchworm Life Cycle

Inchworms, also known as measuring worms or spanworms, are the larvae of moths belonging to the Geometer family. Let’s dive into their life cycle and learn more about these fascinating creatures.

Eggs: The life cycle begins when adult moths lay their eggs, usually on the leaves of various trees and shrubs. During this stage, the tiny eggs remain inconspicuous and well-hidden.

Larvae: Once the eggs hatch, the inchworm larvae emerge. You may recognize these creatures by their distinctive looping motion as they move along leaves. The larvae feed on a variety of plants, including deciduous trees, shrubs, and conifers. Some species are even specific about their choice of plant for feeding. This stage is crucial for their development, as they grow and molt multiple times before pupation.

Here are a few interesting features of inchworm larvae:

  • Colors can range from yellow-green to brown or black
  • A white stripe might run along the side of their body
  • The number of prolegs on the back half of their abdomen can vary

Cocoons: After the larvae have fed and grown enough, they create a cocoon for their next stage – pupation. These cocoons are usually found on tree bark, leaf litter, or even the ground. Inchworms remain protected inside their cocoons while they transform into adult moths.

Adult Moths: Finally, the adult moths emerge from their cocoons. With their newfound wings, these moths fly in search of partners to mate with and continue the life cycle. Adult moths reproduce and lay eggs, allowing the entire process to start anew.

As you explore your surroundings, keep an eye out for inchworms and their various life stages. Remember to appreciate their unique way of moving and the role they play in the ecosystem.

Inchworms and Their Environment

Inchworms, also known as cankerworms, are often found in the foliage of various trees. They typically thrive in deciduous trees such as apple, maple, oak, and hickory trees. However, they can also be found on pine, fir, and other conifer trees in North America. Inchworms prefer trees with abundant leaves and bushes where they can easily find food and camouflage themselves from predators.

As small insects, inchworms have a fascinating way of moving. Their unique movement involves stretching and contracting their bodies to create a loop, giving them an “inchworm” appearance. Inchworms are generally active during the warmer months, as their main food source is tree leaves. They consume a variety of deciduous and coniferous tree foliage.

Here’s a brief comparison of the trees inchworms prefer:

Deciduous Trees Coniferous Trees
Apple Pine
Maple Fir
Oak
Hickory

In winter, cankerworm populations tend to shrink because deciduous trees lose their leaves. This demonstrates the importance of the trees’ foliage to their survival. Despite the scarcity of food during winter, you can still find some inchworms on evergreen trees, as they can feed on the needles.

Aside from trees, inchworms can also survive on other plants, such as bushes and lichen. These alternative food sources may provide sustenance when tree leaves are less abundant. It’s important to keep an eye out for significant inchworm populations in your area, as they can be a potential threat to the health of your trees.

When encountering inchworms in your environment, remember to take note of the trees and plants they inhabit. This can help you understand their feeding habits and protect your trees from potential infestations.

Inchworms as Pests

Inchworms can become pests in various environments, causing damage to plants and crops. They mainly feed on ornamentals, native trees, and shrubs as they belong to a family of moths called geometers1. Some inchworm species focus on conifers, while others prefer deciduous trees and shrubs1. Knowing how to manage inchworms as pests is essential for preserving the health and productivity of your garden and landscape.

One of the ways to control inchworm populations is through the use of pesticides. However, using chemical pesticides may also harm beneficial insects and leave residues in the environment. So, it is crucial to consider natural methods before resorting to chemicals.

For instance, Bacillus thuringiensis (Bt) is a bacterium that is effective in controlling many caterpillar pests, including inchworms1. It is a natural, organic pesticide that targets caterpillars without harming other insects or the environment. To use Bt, you can spray it on affected plants following the instructions provided on the product label.

Encouraging natural predators in your garden is another effective way to manage inchworms and other pests. Beneficial insects, such as parasitic wasps2, feed on various pests without causing damage to your plants. You can attract these natural predators by planting flowers and herbs that provide nectar and pollen.

In summary, inchworms can pose a threat to your ornamentals, trees, and shrubs. To manage them as pests, it is essential to consider natural methods, like Bacillus thuringiensis and encouraging natural predators, before using chemical pesticides.

Defense Mechanisms of Inchworms

Inchworms have developed several ways to protect themselves from predators. One such predator they encounter are birds. To avoid being an easy meal for these skillful hunters, inchworms employ various defensive strategies.

Their color can play a big role in their protection. Inchworms like the black variety blend in with their surroundings, making it difficult for predators to spot them. Others exhibit bright colors like yellow or gray which can serve as a warning sign, indicating that they may not be a safe or pleasant meal for the predator.

Inchworms also produce silk to navigate their environment. This silk allows them to quickly drop from a branch when they detect a threat. Once out of harm’s way, they can then use their silk to climb back up the plant.

Avoiding other predators such as bugs, yellow jackets, paper wasps, ground beetles, and spiders is a challenging task. Inchworms have evolved a few tricks to help them evade these threats in their environment. Here’s a quick comparison table of some of their predators and what inchworms do to evade them:

Predator Inchworm Defense
Birds Camouflage, dropping with silk
Bugs Camouflage, hiding
Yellow Jackets Camouflage, quick movements
Paper Wasps Camouflage, dropping with silk
Ground Beetles Camouflage, hiding
Spiders Camouflage, escaping by silk

To remember some of the key features of inchworm defense mechanisms, check out these bullet points:

  • Camouflage for blending in
  • Bright color warnings
  • Silk production for vertical movement
  • Hiding from predators
  • Quick, erratic movements

By using these strategies, inchworms increase their chances of survival and continue to thrive in their environment. Remembering these tips may help you spot these fascinating creatures when exploring nature.

Inchworm Effects on Other Organisms

Inchworms, also known as measuring worms or spanworms, are caterpillars that belong to the family of moths called geometers. They feed on a variety of plants, including ornamentals like rhododendron as well as native trees and shrubs1. Due to their feeding habits, inchworms can affect the growth and health of diverse plant species.

When it comes to crops, inchworms may pose a threat, depending on the species and the plants they prefer to consume. For instance, some feed exclusively on conifers, while others focus on deciduous trees and shrubs1. This means that certain crops might suffer damage due to inchworm feeding. Be aware of inchworm infestations in your garden or fields, as these caterpillars could become a nuisance.

In relation to humans and pets, inchworms generally don’t pose any direct harm. They do not bite or sting, and they are not known to transmit diseases. However, a significant infestation can lead to plant damage that may indirectly affect you if it impacts your garden or crop yield1.

In conclusion, inchworms can have various effects on different organisms, with their feeding habits leading to potential damage to plants and crops. It’s essential to monitor your plants for signs of inchworm presence and take appropriate measures to control their population when necessary.

Footnotes

  1. (https://hortsense.cahnrs.wsu.edu/fact-sheet/common-insects-and-mites-inchworms/) 2 3 4 5 6 7

  2. (https://extension.usu.edu/archive/give-inchworms-an-inch-and-theyll-eat-a-mile) 2

  3. (https://extension.umn.edu/yard-and-garden-insects/tomato-hornworms)

  4. (https://hort.extension.wisc.edu/articles/hornworms/)

  5. (https://treefruit.wsu.edu/crop-protection/opm/fruitworms/)

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 – Possibly Pink Inchworm

 

Subject:  Caterpillar
Geographic location of the bug:  Denton, Texas
Date: 05/02/2019
Time: 12:05 AM EDT
Your letter to the bugman:  This caterpillar is very thin, about 1 inch long. I found it on some Mystic Spires salvia. I would like to know what it will turn into.
How you want your letter signed:  M. Hector

Possibly Pink Inchworm

Dear M. Hector,
This is an Inchworm or Spanworm in the family Geometridae.  We have received images of pink Inchworms in the past, and we have not been able to provide more than a family identification, including this pink Inchworm from Minnesota in 2009.  We also located an image of a pink Inchworm on BugGuide that is only identified to the family level.  So, the best we can do is provide a family identification at this time.  Moths from the family Geometridae often have a very distinct shape including wings with scalloped edges.  Though it does not answer your question, you might be amused by this 2012 request to identify a pink Inchworm that garnered a Nasty Reader Award.

Unknown Pink Caterpillar on Salvia

Upon further scrutinizing your other images, we cannot even be certain that this is an Inchworm in the family Geometridae.  Do you by chance have a lateral view that shows the legs?

Letter 2 – Red Inchworm??

 

I found this inchworm on my clematis flower. It is red in color. I can’t seem to find a “red” inchworm on the internet. Someone told me it is an inchworm because it has legs in the front and legs in the back, not in the middle, and it moves by moving its center up … like an inchworm. But is red or maybe dark pink in color. I have a picture but it is blurry. The first pic is on the flower. The second pic I took it off and put it on a napkin. It is very tiny so hard to take a pic with my camera.
Thanks,
Claire

Hi Claire,
Inchworms are the caterpillars of Geometrid Moths. Sorry, I don’t know of a pink or red caterpillar, but there is often little information on caterpillars. I will continue to check and possibly get back to you.

Letter 3 – Possibly a Camouflaged Looper

 

Subject: strange something found crawling on my house. what is it?
Location: South Central Texas
October 15, 2013 3:21 pm
I found this strange thing crawling on the exterior of my house. I live just west of San Antonio Texas and the time of year was the fall. I was using a z tool to try and grab it off the wall and as soon as I got near, it acted as if it sensed something and kind of stood up on one end as if it was afraid.
Signature: Please tell me what this is. thanks, Nancy K

Possibly Camouflaged Looper
Possibly Camouflaged Looper

Hi Nancy,
Our best guess is that this might be a type of Inchworm Caterpillar known as a Camouflaged Looper
Synchlora frondaria.

Letter 4 – Showy Emerald Caterpillar

 

beautiful fern-like inchworm found in Tennessee
Hello whatsthatbug! Thought i’d add to the bizarre inchworm pictures with these snapshots of a strange brown fern frond i saw waving in the breeze-less air of Franklin, Tennessee this September. Upon closer inspection, it was of course this lovely creature. I’ve attempted to look up caterpillars of tennessee, but haven’t found this guy. Any help, or a point in the right research direction would be appreciated! thank you for the lovely site!
JD

Hi JD,
We quickly identified this inchworm as a Showy Emerald, Dichorda iridaria by using BugGuide.

Letter 5 – Snowbush Spanworms

 

the hungry catapllers
Location:  satellite beach, fl
August 8, 2010 8:42 am
i found these hungry catapillers. eating away at what left of bushes in my front yard. All I know they black and green with legs in front and back.
neal

Snowbush Spanworms

Hi Neal,
Though we were not familiar with this caterpillar, we quickly identified them as Snowbush Spanworms,
Melanchroia chephise, the caterpillar of the White-Tipped Black, because the caterpillars appeared to have but two sets of prolegs at the hind end, indicating the family Geometridae.  BugGuide provides this information:  “larvae feed on plants in the spurge family (Euphorbiaceae) such as Breynia and Phyllanthus species.”  We are having a difficult time believing these caterpillars have defoliated your shrubs as depicted in your photographs.  We suspect a rampant chain saw was the real culprit.

Snowbush Spanworm

Letter 6 – Spanworm

 

Subject: Ugliest caterpillar
Location: Southeast Michigan
July 17, 2015 8:38 am
I found this in someone’s garden while i was working. What type of moth or butteffly might it be? I have never seen anything like it before.
Signature: – ruth the gardener

Spanworm
Spanworm

Dear Ruth the gardener,
This is an Inchworm or Spanworm in the family Geometridae, and larvae can often be very difficult to identify to the species level.  One of the most noticeable features on your Spanworm is the red color of the spiracles or breathing openings on the side.  We thought that might lead us to an identification, but alas, it did not.  Knowing the plant the Spanworm was feeding upon might help.  Though we can make out a leaf on the right, we cannot tell the identity of the plant.  If you can supply us with the plant, we might have better luck.

Letter 7 – Juniper Twig Geometer is Unknown “diamondback” Spanworm on Cedar

 

Subject: Help Identify
Location: Talbott, Tn 37877 in a 80 year old cedar tree
July 20, 2016 5:04 pm
My daughter recently found this little guy hanging from what appeared to be a spider web but upon further examination could have been its own silk. I have been told that it could be a chameleon worm but I can’t find any info to back it up. Can you help identify please? I would like to know incase my daughter finds another one I can tell her to either stay away or its safe to touch. Thanks in advance!
Bryan Hux
6th Grade Science
Jefferson Middle School
Jefferson City Tn
Signature: Bryan Hux

Unknown Spanworm
Juniper Twig Geometer

Dear Bryan,
Though we have not had any success with a species identification, we can tell you this is an Inchworm or Spanworm in the family Geometridae, and it poses no threat to humans as it is neither venomous nor poisonous.  We wish we could be certain that the cedar upon which it was found was also the host plant as we couldn’t find any similar looking Spanworms associated with cedar.  Perhaps one of our readers will have more success at a species identification than we have had searching BugGuide and other sites. 

Karl finds the ID
Hi Daniel and Bryan:
It looks like a Juniper-twig Geometer caterpillar (Patalene olyzonaria). Despite the name, the principal food for the caterpillars is given as cedars of all varieties. Regards, Karl

Thanks so much Karl.  We like our name “Diamondback Spanworm” since the BugGuide description is:  “Larva: body brownish or grayish with dark angular lines dorsally and laterally, creating a diamond-shaped pattern; whitish patches below angular lines in subdorsal area; pair of black dorsal warts on ninth abdominal segment; head brown and gray with dark brown herringbone pattern on lobes.”

Authors

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  • 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.

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  • 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.

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3 thoughts on “What Do Inchworms Eat: A Quick Guide to Their Diet”

  1. The snowbush is a very invasive pest. I had them last year on my snow bushes out front and they all be destroyed them. And, yes they do eat the bark and all the leaves down. If left alone, they will eat your plants to the point where they cannot regrow

    Reply
  2. Maybe its an albino. Probably wont live long in the wild because without camouflage it will be easily picked off. Just a thought. Not sure if bugs or insects can be albino, but if animals can I don’t see why bugs or insects can’t.

    Reply
  3. I found a very tiny dark pink inchworm yesterday..which is how I found this page. I also found the typical bright green AND a very dark purple-almost brown. All were tiny inchworms. I mean about the width of my pinky fingernail-about half an inch fully stretched. I am trying to find out why so many and do they camoflauge? Or are they all different species? I find that doubtful.

    Reply

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