What Do Caterpillars Eat? A Quick Guide for Curious Minds

Caterpillars are fascinating creatures that often catch our attention due to their unique appearances and insatiable appetites. You may have wondered what these fuzzy little larvae of butterflies and moths consume to help fuel their remarkable transformations. Let’s dive into the world of these garden visitors to better understand their dietary preferences.

While some caterpillars are generalists that feed on a wide variety of plants, many species are more specific about their food choices. In fact, certain caterpillars have evolved to feed exclusively on particular types of plants, making them highly specialized eaters. For instance, the iconic Monarch butterfly caterpillar will only eat milkweed, while the Eastern Black Swallowtail caterpillar prefers members of the carrot family, such as fennel and parsley.

As you observe caterpillars in your garden or yard, you may notice similarities among species that eat the same types of plants. By understanding their feeding habits, you’ll be able to not only appreciate their roles in the ecosystem but also find opportunities to support these fascinating critters that eventually transform into beautiful butterflies and moths.

General Diet of Caterpillars

Herbivorous Caterpillars

Caterpillars are mostly herbivores, feeding on leaves, fruits, and other plant parts. As generalist feeders, some eat a variety of plants. For example, yellow bear caterpillars consume a wide range of plants from spring to fall.

On the other hand, specialist feeders are selective in their diet and prefer specific host plants. For instance, redhumped caterpillars feed only on fruit or nut trees but do not eat the fruits or nuts themselves.

Some common host plants for herbivorous caterpillars:

• Salad greens
• Green beans
• Broccoli
• Cauliflower
• Cabbage
• Carrots

Carnivorous Caterpillars

Although rare, some caterpillars are carnivorous, preying on insects and feeding on animal-derived materials. They often use stealth, camouflage, or speed to capture their prey. In these cases, the carnivorous caterpillars may provide ecological benefits by controlling insect populations.

Friendly Reminder: Keep your garden diverse and balanced to accommodate both herbivorous and carnivorous caterpillars, as they play essential roles in their ecosystems.

Caterpillar’s Preferred Plants

Milkweed for Monarch Caterpillars

Monarch caterpillars have a specific preference for milkweed. Feeding on milkweed helps them to store toxins in their bodies, which makes them unattractive to predators. Some common milkweed varieties for Monarchs include:

• Common Milkweed
• Swamp Milkweed
• Butterfly Weed

Various Trees for Different Species

Caterpillars of different species are fond of various trees, such as:

• Oak
• Apple
• Willow
• Birch
• Ash
• Pine

For example, the redhumped caterpillar consumes entire leaves of fruit trees like apple and cherry trees, whereas the pine processionary moth caterpillar prefers pine trees.

Common Herbs and Grasses

Caterpillars also feed on common herbs and grasses, such as:

• Clover
• Parsley
• Dill
• Alfalfa
• Thistle
• Wild grasses
• Nettles

These grasses and herbs are often abundant in gardens and meadows, making them an easily accessible food source for caterpillars.

Fruits and Flowers

Some caterpillars enjoy the taste of fruits and flowers, including:

• Mistletoe
• Violets
• Asters

Caterpillars feeding on fruit trees not only consume the leaves but may also eat the fruits themselves, which can cause damage to fruit production.

Comparison Table

In summary, caterpillars enjoy a diverse diet consisting of plants commonly found in various habitats, including milkweed for Monarchs, a variety of trees for species like redhumped and pine processionary caterpillars, and common herbs, grasses, fruits, and flowers for species such as the yellow bear and woolly bear caterpillars. Knowing the preferred plants of different caterpillar species can help you identify them and effectively manage their presence in your garden or orchard.

Feeding and Foraging Patterns

Caterpillars can have a wide variety of eating habits, but most of them primarily feed on leaves from trees and shrubs. Some caterpillars munch on twigs, stems, seeds, or nectar, depending on their species and the availability of food sources in their environment.

Generally, caterpillars can be categorized as generalist feeders or specialist feeders. As a generalist feeder, a caterpillar isn’t too picky about its diet and can feed on multiple types of plants. Examples of generalist feeders include the Eastern Tent Caterpillar and the Forest Tent Caterpillar. These two caterpillars can be found feeding on the leaves of various trees, such as apple trees or other fruit trees.

In contrast, specialist feeders have a more selective diet, focusing on specific plants or plant parts. For example, the Monarch caterpillar primarily feeds on the leaves of milkweed plants. Specialist feeders have evolved to be more selective in their diet due to the specific nutritional requirements or to avoid predators by blending in with their preferred food source.

Here’s a simple comparison table to illustrate the differences between generalist and specialist feeders:

In summary, the feeding habits of caterpillars depend on the species, with some being generalists that feed on several types of plants, while others are specialists with a more selective diet. Be sure to take note of the differences in their foraging patterns for a better understanding of these fascinating insects.

Caterpillars in Captivity

When raising caterpillars in captivity, it’s crucial to provide an appropriate food source. As there are two types of feeders, generalist and specialist caterpillars, their dietary requirements differ.

Generalist feeders can eat a wide range of plant species. This makes them adaptable, and they’re easier to care for in captivity. For example, the Redhumped Caterpillar can munch on various host foliage source.

On the other hand, specialist feeders are selective, developing on a specific host plant that is necessary for their survival. An example is the Eastern tent caterpillar which feeds on the leaves of wild apple trees source.

Here’s a comparison table to illustrate the differences:

To cater to their dietary needs, research your captive caterpillar’s preferred food source. Some tips include:

• Identify the plant species on which you found the caterpillar.
• Look into the natural habitat of the caterpillar species.

By providing the right food source in captivity, your caterpillars will grow optimally and eventually transform into butterflies or moths.

Defensive Mechanisms in Diet

Caterpillars have developed various defensive mechanisms to protect themselves from predators. One of these mechanisms involves incorporating toxins and chemicals from their diet into their own bodies.

For instance, some caterpillars feed on plants that contain toxic substances, which then accumulate in their body, making them less appealing to predators. An example is the Monarch butterfly caterpillar that feeds on milkweed, a plant rich in toxic chemicals called cardenolides.

Here are some caterpillar defensive mechanisms related to their diet:

• Incorporation of plant toxins
• Production of their own chemicals
• Presence of hair or spines

Some caterpillars can produce their own chemicals for defense. These chemicals can be irritating or toxic to their predators, making them unpalatable. For instance, the tobacco hornworm caterpillar has a gland that produces nicotine, which can be harmful to its predators.

Another common defensive mechanism is the presence of hair or spines on the caterpillar’s body. These structures can cause physical irritation or even harm to predators when they try to eat the caterpillar. The hairs or spines may also contain additional toxins, further discouraging predators. An example of a hairy caterpillar is the stinging rose caterpillar, which has venomous spines.

In conclusion, caterpillars rely on a combination of their diet and physical adaptations to protect themselves from predators. By incorporating toxins and chemicals from their food sources and utilizing defensive structures like hair and spines, they can successfully deter many potential threats.

Caterpillars and Their Predators

Caterpillars, the larvae of butterflies and moths, spend most of their time eating plant leaves, flowers, and fruits to grow and develop. But did you know that they also need to defend themselves from various predators? Let’s discuss their main predators and how they try to protect themselves.

Birds are one of the primary predators of caterpillars. Species like robins, bluebirds, and chickadees are always on the lookout for these protein-rich snacks. To avoid birds, many caterpillars have developed camouflage strategies and bright colors that signal potential danger.

Ants might also be a threat to caterpillars, as they can be quite territorial and aggressive. However, some species of caterpillars have evolved impressive defensive strategies, such as having special glands that secrete substances to keep ants at bay or even developing mutually beneficial relationships, where ants protect caterpillars in exchange for sweet secretions.

Insects like predatory wasps and flies are known to prey on caterpillars as well. To avoid becoming a meal, some caterpillars employ chemical defenses they obtain from their diet, making them distasteful or even poisonous to their predators. Others mimic the appearance of unpalatable insects to deceive predators.

While not predators themselves, some worms could pose a threat to caterpillars when sharing the same environment. Parasitic wasp larvae, for example, can infest the bodies of caterpillars, feeding on them from the inside.

In summary, caterpillars face multiple threats from the following predators:

• Birds
• Ants
• Insects
• Worms (indirectly, through parasitic behavior)

Despite these challenges, they rely on an impressive array of defensive strategies, such as camouflage, bright warning colors, chemical defenses, and mutually beneficial relationships to survive and thrive.

Impact of Pesticides and Chemicals

Pesticides play a crucial role in agriculture by reducing the loss of crops and improving the yield and quality of food. However, these chemicals can also have unintended consequences on the environment, including the feeding habits of caterpillars.

When you use pesticides on plants, you might see immediate benefits, such as higher crop yields and healthier produce. For instance, by killing caterpillars that feed on cabbage, the quality of the crop improves. But these chemicals also present potential hazards to non-target organisms, like caterpillars.

There are different types of pesticides, and their effects vary:

• Organophosphates and carbamates can impact the nervous system.
• Some pesticides could irritate the skin or eyes.
• Certain chemicals may be carcinogenic or affect the hormone or endocrine system in the body.

You should be aware that applying pesticides can impact not only the caterpillars but also the entire food chain and ecosystem. For example, birds and other animals that rely on caterpillars as a food source may suffer as their populations decrease.

In conclusion, it’s essential to carefully consider the potential consequences of pesticide use on caterpillars and the ecosystem. Remember to look for other alternative methods, such as biological or cultural control, to manage pests while minimizing the risks associated with chemical use.

Role of Caterpillars in Ecosystem

Caterpillars play a vital role in the ecosystem as they serve as a critical food source for many predators. As herbivores, they feed on various plants, enabling the energy obtained through plant consumption to pass up the food chain. Birds, in particular, rely heavily on caterpillars for nourishment, especially during their breeding season.

For instance, Yellow Bear and Woolly Bear caterpillars consume a wide variety of plants, such as mint family (Lamiaceae) and carrot family (Apiaceae) herbs like oregano, thyme, and cilantro source. In turn, these caterpillars sustain various predators that rely on them.

Moreover, as caterpillars feed on plants, they inadvertently provide opportunities for parasitic wasps to thrive. These wasps serve as essential biological control agents, helping to maintain the balance in the ecosystem source.

Lastly, butterflies and moths also play a role in plant pollination. With over 1,400 species in North Carolina alone, many caterpillars transform into adult moths and butterflies, offering benefits to the ecosystem, beyond their role as larvae source.

In summary, caterpillars have a crucial role within the ecosystem, acting as a food source for predators, herbivores that transfer energy in food chains, and enabling the survival of beneficial parasitic wasps.

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 – Hornworm eating Plumeria in Mexico

Subject: Caterpillar eating plumeria leaves
Location: Puerto Vallarta
May 10, 2017 6:37 am
Normally, the only caterpillars that eat plumeria leaves are tetrio and an occasional starving monarch. This young one, munching away in Puerto Vallarta this May, has everyone stumped – no one has seen one before. Any ideas?
Signature: Diana

Dear Diana,
The forward facing, filamentous, caudal horn is quite unusual in this caterpillar, and we suspect like the Tetrio Sphinx, it is a Hornworm in the family Sphingidae.  We do not recognize it either and we are going to request assistance from Bill Oehlke.  It if is a Sphingiid, we suspect Bill may request permission to use the images on his very comprehensive site.

Update:  Thanks to a comment from Bostjan Dvorak, we have learned that this Hornworm is Isognathus leachii.  According to Sphingidae of the Americas:  “Larvae have long tails; colouration suggests they are unpalatable to birds.”

Many thanks for the follow-up: I’ve posted in the plumeria Facebook forums. You now have Mexican Pacific coast to add to the confirmed range, and plumeria as a larvae host plant, and like tetrio, they eat a lot of leaves! I’ve also alerted Dr. Criley at the Univ of Hawaii in case it shows up in their groves.  Excellent work!

Letter 2 – Pipevine Caterpillars accused of eating Pecan Trees!!!

Subject: Red Horned Catepillar Type Bug
Location: Southern Arizona
September 5, 2012 10:30 pm
Hi – Found this in Southern Arizona and I think it is eating my pecan trees. Not sure what it might be, but hoped you might be able to help. Sure is an interesting looking creature. Thanks for looking!
Signature: Steven

Dear Steven,
These are Pipevine Swallowtail Caterpillars, and they will eventually metamorphose into beautiful butterflies.  To the best of our knowledge, they do not feed on the leaves of pecan trees, but rather, on pipevine, according to BugGuide.  Perhaps you have pipevine growning amongst your pecan trees.

Letter 3 – Caterpillar Hunter Larva eats Cutworm

Caterpillar Eater
October 29, 2009
We found these bugs all over the place. They seem to be foraging for caterpillars that are also very heavy this year. They look like caterpillars, but only have six legs. Also, they will dig a hole in the ground and leave their back end lying outside of the hole. Any ideas on what this is? We’ve lived here for four years and have never seen anything like it.
Shaune Martinez
Sandia, TX

Hi Shaune,
This is a beetle larva in the genus Calosoma, commonly called Caterpillar Hunters.  There are several species of Calosoma in Texas, and it is impossible for us to determine your exact species.  The Fiery Searcher, Calosoma scrutator, is one possibility.

Letter 4 – Basilisk Lizard eats Silk Moth Caterpillar in Costa Rica

UNNECESSARY CARNAGE
Tue, Mar 17, 2009 at 5:55 AM
Hi Bugman,
This basilisk lizard is not a pet. While sitting out by the pond fishing, this female ran over and grabbed the poor caterpillar. It was right in front of me on the ground and I didn’t see it until she grabbed it and it was too late. Do you have any idea what kind of caterpillar it was? It took the lizard around ten minutes to scarf it down. She looked pretty satisfied after she ate her prize.
Jordan
Costa Rica

Hi Jordan,
This is far from unnecessary carnage. That section of our website is devoted to the hapless creatures that are squashed and swatted by humans out of ignorance. This Basilisk Lizard is dining on a Giant Silk Moth Caterpillar as part of the beautiful Food Chain cycle that dictates many creature must eat or be eaten. It is difficult to ascertain the exact species of the caterpillar from the camera angle, but we are relatively certain it is in the family Saturniidae.

Letter 5 – Unknown Caterpillar eats Aloe in South Africa

Subject: Caterpillar
Location: Cape Town, South Africa
January 12, 2014 2:52 am
Please help me identify this caterpillar. I have an aloe type plant in my garden which these caterpillars have destroyed.
Signature: D Nash

Dear D Nash,
Our initial attempts to identify this Aloe devouring Caterpillar by using our typical methods did not prove fruitful.  We always state that knowing the food plant is a tremendous assistance in insect identification, but “aloe eating caterpillar South Africa” turned up nothing for us.  These might be Tussock Moth Caterpillars, so that is our next avenue of research.  We will let you know if we discover anything.  We are certain they are Moth Caterpillars, but beyond that, we don’t know.

Letter 6 – Gossamer Wing Caterpillar on Buckwheat

Subject:  caterpillar id?
Geographic location of the bug:  oakland california
Date: 08/23/2021
Time: 07:17 PM EDT
Your letter to the bugman:  my red buckwheat in the oakland hills has these small caterpillars on them.  Any idea what they are?
How you want your letter signed:  Alex

Dear Alex,
This is the Caterpillar of a Gossamer Winged Butterfly in the family Lycaenidae, but we are not certain of the species.  It might be one of the Hairstreaks like this BugGuide image of a Gray Hairstreak Caterpillar on Buckwheat, or it might be one of the Blues, like this BugGuide image of a Square Spotted Blue Caterpillar also on BuckWheat.

Thank you for the ID!