Caterpillar Predators: Who’s on the Menu? Exploring Natural Predation

Caterpillars are a common sight in gardens and wild habitats, often munching away on leaves and causing damage to plants. As a gardener or nature enthusiast, you might be curious about what creatures help keep these voracious eaters in check. In this article, we’ll explore the wide variety of animals that prey on caterpillars, providing a natural form of pest control.

Birds are often the first thing that comes to mind when thinking about caterpillar predators. Many bird species, such as chickadees, warblers, and cuckoos, feast on these soft-bodied insects. But birds aren’t the only creatures that eat caterpillars. You might be surprised to learn that numerous insects and other invertebrates also help control caterpillar populations.

While browsing through this article, you’ll discover how a diverse group of animals, including parasitic wasps, predatory beetles, and even spiders, make caterpillars a part of their diet. Understanding the role these predators play in the ecosystem can help you appreciate the delicate balance of nature and the importance of maintaining biodiversity. So, let’s dive in and learn more about the fascinating world of caterpillar predators.

Caterpillars: A Brief Overview

Caterpillars are the larval stage of insects in the order Lepidoptera, which includes both butterflies and moths. As these creatures transform from their larva stage to their mature adult stage, they undergo a fascinating journey.

During their time as caterpillars, these creatures display several interesting characteristics:

  • Prolegs: In addition to their six true legs, caterpillars have fleshy, temporary legs called prolegs that help them grip surfaces while they crawl.
  • Voracious Appetites: Caterpillars spend most of their time eating, as they need to gather enough energy and nutrients to transform into their adult form.

For example, the black swallowtail caterpillar spends most of its life consuming leaves of plants in the carrot family, such as parsley, celery, and dill, before eventually forming into a chrysalis and becoming a fully grown black swallowtail butterfly.

While caterpillars can cause extensive damage to plants due to their eating habits, it’s essential to remember that they play a crucial role in the natural world. Many animals rely on caterpillars as a food source, and their eventual transformation into butterflies and moths allows for essential pollination to occur.

It’s worth considering the diversity of caterpillars and their adult forms. For instance, the redhumped caterpillar can be easily distinguished from other species by the distinctive red hump on its back.

In conclusion, the caterpillar is a fascinating and essential part of our ecosystem. As you encounter these intriguing creatures, take a moment to appreciate their unique characteristics and the vital role they play in the world around you.

Natural Predators of Caterpillars


Many bird species, such as warblers, robins, wrens, and woodpeckers, enjoy feasting on caterpillars. In particular, orioles are known to meticulously hunt down caterpillars for a tasty meal. These birds naturally help control caterpillar populations in your backyard and garden.


A variety of insects prey on caterpillars:

  • Ladybugs: They target soft-bodied insects like caterpillar eggs and larvae.
  • Ground beetles: These beetles are particularly voracious, feeding on a wide range of insects, including caterpillars.
  • Parasitic wasps: They lay their eggs inside caterpillar eggs or larvae, eventually killing them once the wasp larvae develop.
  • Assassin bugs and lacewings: Both insects prey on caterpillars in their various life stages.

You can encourage the presence of these beneficial insects by planting herbs like parsley and coriander or flowers like sweet alyssum in your garden 1.

Reptiles and Amphibians

Several reptiles and amphibians enjoy eating caterpillars too:

  • Frogs and toads: With their sticky tongues, they are natural predators of many insects, including caterpillars.
  • Lizards and newts: Another group of effective caterpillar predators that will consume them as part of their varied diet.

Attracting these animals to your garden can provide a natural method of caterpillar control.


Various ground-dwelling mammals also feed on caterpillars:

  • Small rodents: Mice, rats, and squirrels consume caterpillars as a supplemental food source.
  • Raccoons: Opportunistic feeders that enjoy a range of insects in their diet, including caterpillars.

Owls, while not ground-dwelling, are known to feast on caterpillars as part of their diverse diet.

By understanding the natural predators that feed on caterpillars, you can effectively utilize them to control caterpillar populations in your garden or yard.

Pest Control: Caterpillars as Prey

Human Intervention

Caterpillars are considered pests in some situations because they can damage plants and crops. One way to control their population is through human intervention. You can handpick caterpillars from your plants, but remember to wear gloves to avoid skin irritations caused by the caterpillar’s hairs or spines.

Another option is to introduce native plants into your garden. These plants attract natural predators of caterpillars, like beetles, spiders, and assassin bugs, which can help keep their numbers in check.

Beneficial Insects

Beneficial insects are another important component in controlling caterpillar populations. Here are some key beneficial insects:

  • Ladybird Beetles: Also known as ladybugs, these insects feed on aphids and other pests. They’re not directly involved in preying on caterpillars, but they can indirectly contribute by controlling the pests that attract caterpillars to your garden.
  • Parasitoid Wasps: Parasitoid wasps lay their eggs inside caterpillars, eventually killing the caterpillar as the wasp larvae develop. There are many species of parasitoid wasps that specialize in attacking caterpillars.
  • Spiders: While not technically insects, spiders play a vital role in controlling caterpillar populations. They catch caterpillars in their webs or hunt them down as food.

Here’s a comparison table of the beneficial insects mentioned:

Insect Primary Prey Effect on Caterpillars
Ladybird Beetles Aphids Indirect (controls pests)
Parasitoid Wasps Caterpillars Direct (kills caterpillars)
Spiders Insects (including caterpillars) Direct (preys on caterpillars)

By encouraging the presence of these beneficial insects and spiders in your garden, you can create a natural, eco-friendly way to control caterpillar populations.

Nutrition from Caterpillars

Caterpillars can be a great source of nutrition for various animals and even humans in some parts of the world. They are rich in vital nutrients, providing essential elements for a balanced diet.

Caterpillars are an excellent source of protein. Consuming them can help meet your daily protein requirements. Protein is crucial for your body’s growth, repair, and maintenance.

Besides protein, caterpillars also contain iron. Iron is a vital element needed for hemoglobin production, carrying oxygen throughout your body. Including caterpillars in your diet can help prevent anemia. However, it is essential to remember that caterpillars are not the only source of iron—many other foods can provide you with this nutrient as well.

Caterpillars contain fats too, including saturated and unsaturated fats. These fats contribute to your body’s energy needs and support cell growth. However, it would be best if you had a balance between saturated and unsaturated fats to maintain a healthy diet.

There are other nutrients found in caterpillars, such as calcium. Calcium is essential for bone health, nerve function, and muscle contraction. Though caterpillars are not the primary source of calcium in most diets, they can still contribute to meeting your daily calcium needs.

Here’s a comparison table showing some nutritional values of caterpillars:

Nutrient Amount (per 100g)
Protein 20g
Iron 3.5mg
Fats 12g
Calcium 150mg

In conclusion, caterpillars can offer various nutrients, such as protein, iron, fats, and calcium. Due to their high nutritional value, they can be a beneficial addition to some diets. However, please remember that there are many alternative sources for these nutrients too, and caterpillars should be consumed as part of a balanced diet.

Notable Species and Their Predators

Monarch Caterpillars

Monarch caterpillars are known for their distinctive appearance, featuring black, white and yellow stripes. They are primarily found in North America and thrive on milkweed plants. But despite their vibrant colors, which serve as a warning signal to predators, monarch caterpillars still have some natural enemies.

  • Birds: Some bird species, such as orioles and grosbeaks, have learned to tolerate the toxic compounds found in monarch caterpillars and are known to feed on them.
  • Small mammals: Similarly, mice and squirrels have adapted to eating monarch caterpillars occasionally, despite their toxicity.
  • Insects: Various insects like ants, ladybugs, and lacewings also prey on monarch caterpillars and their eggs.

Swallowtail Caterpillars

Swallowtail caterpillars are commonly found in multiple regions, including Africa, East Asia, and North America. Two well-known species are the tiger swallowtail and the black swallowtail.

Species Region Coloration
Tiger Swallowtail North America Green with yellow and blue eyespots
Black Swallowtail North America, Africa, East Asia Green with black crossbands and orange spots

Swallowtail caterpillars are targeted by a variety of predators as well. Here’s a list of some of their common foes:

  • Birds: Various avian species are known to prey on swallowtail caterpillars, though these insects attempt to defend themselves by displaying osmeterium, a fleshy, forked structure that releases a foul odor to deter predators.
  • Spiders: Many spiders, such as crab spiders and jumping spiders, are skilled at capturing and feeding on swallowtail caterpillars.
  • Parasitoids: Swallowtail caterpillars are also vulnerable to parasitoid wasps and flies, which lay their eggs on or inside the caterpillar, eventually leading to the caterpillar’s demise as the larvae develop inside them.

In summary, you’ll find that both monarch and swallowtail caterpillars face numerous threats from various predators, utilizing different strategies to survive in their respective environments.

Defenses and Challenges

Caterpillars have a vast array of predators, and to survive in such a hostile environment, they’ve developed various defense mechanisms. For example, some caterpillars use camouflage to blend in with their surroundings, making it difficult for their predators to spot them.

Predators of caterpillars include:

  • Birds
  • Insects (such as ants, wasps, and ladybugs)
  • Mammals (such as bats and mice)
  • Reptiles (such as lizards)

In some cases, caterpillars can exhibit cannibalistic behaviors when resources are scarce, consuming other caterpillars around them. This is an extreme survival tactic, highlighting the challenges they face in their environment.

Omnivores, like some species of ants and flies, also prey on caterpillars. These generalist feeders can adapt their diets to what’s available, increasing the chances they will consume caterpillars when other food sources are scarce. This shows how versatile caterpillars’ predators can be.

The damage caused by caterpillars to plants can sometimes be a giveaway for predators. When these animals chew on leaves and stems, they create visible evidence of their presence. This means they must balance their need to feed with the risk of being detected and consumed by predators.

In conclusion, caterpillars have adapted various strategies to protect themselves from predators, but they still face numerous challenges. Predators like birds, insects, and mammals are always on the lookout for a tasty meal, and caterpillars must rely on their defenses, such as camouflage and sometimes even cannibalism, to survive.



Reader Emails

Over the years, our website, 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 – Immature Predatory Stink Bug eats Monarch Caterpillar


Insect that kills Monarch Butterfly caterpillars
Location:  North Central Wisconsin
August 1, 2010 7:33 pm
My aunt saw this bug killing one of the caterpillars in her garden. Do you know what it is?
Todd Nelson

Spined Soldier Bug Nymph (we believe) feasting on Monarch Caterpillar

Hi Todd,
This hunter is a Predatory Stink Bug nymph in the subfamily Asopinae.  We believe it is a Spined Soldier Bug in the genus
Podisus, but immature insects are often notoriously difficult to properly identify. BugGuide has a nice description of the genus.

Letter 2 – Spined Soldier Bug eats Monarch Caterpillar


Subject:  Stinbug sucking on a monarch caterpillar.
Geographic location of the bug:  Western New York State
Date: 08/09/2018
Time: 09:17 PM EDT
Your letter to the bugman:  My wife was so excited to see a monarch caterpillar in our garden today (8/9/2018), only to discover that its “friend” was sucking its insides out.  I could tell the vampire was a true bug, but I had thought they mostly drank plant sap. How specific are they? Does it specialize in monarchs or does  feed  other larvae? Thanks! You guys are awesome!
How you want your letter signed:  Mark VanDerwater

Spined Soldier Bug preys on Monarch Caterpillar

Dear Mark,
While most Stink Bugs feed on fluids from plants, one subfamily, Asopinae, is predatory.  We believe we have correctly identified your Predatory Stink Bug as
Apoecilus cynicus thanks to this BugGuide image.  According to BugGuide:  “mostly feeds on caterpillars” but luckily they do not limit their diet to solely Monarch Caterpillars so relocating the Predatory Stink Bug far from the milkweed, perhaps in the vegetable patch, would be our solution to repeating this scenario in the future. 

Thank you Daniel! I was poking around insect sights too and came up with the spined soldier bug, Podisus maculiventris. Known to prefer lepidoptera larvae. Also has the dark abdominal tip.

Hi Mark,
We agree that you have provided us with a correction.  The Spined Soldier Bug is another member of the Predatory Stink Bug subfamily, and this BugGuide image is a good match, and the BugGuide description “Black streak on wing membrane + spined humeri are diagnostic” matches your image.  Thanks for bringing this misidentification to our attention. 

Letter 3 – Predatory Stink Bug eats Gypsy Moth Caterpillar


Carnivorous Orange Beetle
Mon, Jul 6, 2009 at 6:37 PM
My wife spotted this pair in the backyard. I don’t know the identity of either bug, but found the scene quite interesting. I’m just curious what was sucking the life out of what.
Beloit, WI

Predatory Stink Bug eats invasive Gypsy Moth Caterpillar
Predatory Stink Bug eats invasive Gypsy Moth Caterpillar

Hi Dave,
We located a nearly identical image on BugGuide, except that three Predatory Stink Bugs in the genus Apateticus are feeding on a Gypsy Moth Caterpillar.  Sadly, BugGuide does not provide any information on the genus and a nymph or immature insect, like the one in your photo, is often quite difficult to identify to the species level.  We can tell you that the Gypsy Moth Caterpillar, Lymantria dispar, is an introduced pest species.  BugGuide has this to say about the range of the Gypsy Moth:  “Native to Eurasia, introduced to North America at Boston, Massachusetts circa 1869 and has been spreading ever since ( US Forest Service ). Michigan, Pennsylvania, and all states to the north and east of these.  Also much of Wisconsin.  Also the northern parts of Illinois, Indiana, and Ohio.  Most of West Virginia is included in the insect’s range, as well as parts of Virginia and North Carolina.  The United States Forest Service estimates the moth’s range is spreading south and west at a rate of about 21 kilometers per year.  In Canada, the Gypsy Moth is present in British Columbia and in much of eastern Canada. ”  BugGuide has the following comments with regards to food, life cycle and general remarks:  “Food Many hardwood species.  A very partial list includes Red Oak, Cherries, Willows, Hickories, and Pines.  Over 500 spp. of plants are known hosts.
Life Cycle In late summer females lay up to 1,000 eggs per egg mass.  The eggs overwinter and hatch in the Spring.  Larvae feed heavily and do considerable damage to forests.  Pupation typically occurs in mid-Summer.
Remarks Etienne Leopold Trouvelot, an amateur entomologist, brought Gypsy Moths into the United States to see if they could be successfully reared for silk culture.  Around 1869 some of Trouvelot’s charges escaped from his home near Boston.  Realizing the potential magnitude of the problem, he reported the escape but no action was taken until the infestation grew serious several years later. Trouvelot later became interested in astronomy and astronomical illustration, and eventually became a Harvard professor of Astronomy. ”

Predatory Stink Bug eats invasive Gypsy Moth Caterpillar
Predatory Stink Bug eats invasive Gypsy Moth Caterpillar

Letter 4 – Anchor Stink Bug eats Monarch Caterpillar


What is this pink and black beetle?
Location: Down East Maine – field
November 17, 2011 9:20 am
I have tried to find out – but not 100% sure – closest I could find was a Calligraphic Beetle? But the shape of his back-end is more pointed than the rounded Calligraphic Beetles I found images of on the Bug Guide website, and the black markings don’t fully match up. This beetle was definitely pink too. I would love your help:) It definitely was taking this monarch caterpillar with it!
Signature: Caroline

Anchor Stink Bug eats Monarch Caterpillar

Dear Caroline,
The predator in this Food Chain drama is an Anchor Stink Bug,
Stiretrus anchorago, and we identified it on BugGuide which notes:  “Adults feed on the larvae of beetles, butterflies, and moths. Stiretrus anchorago is considered an economically beneficial insect, feeding on the larvae of the Mexican Bean Beetle, among other pest species.”  It seems late in the season for this to occur.  When was this photo taken?

Anchor Stink Bug eats Monarch Caterpillar

The photo was taken August 8th.  And thank you soooo much for getting back to me.  Very exciting to know who that was in my backyard!
-Best, Caroline


Letter 5 – Immature Wheel Bug eats Tussock Moth Caterpillar


Spider-like 6 legged grey bug…what is this??
Location: Daytona Beach area, Florida
April 7, 2012 10:45 pm
2 of these bugs have popped up in our area that our family has heard of/seen. We have searched the web and have been unsuccessful in identifying it, with most searches yielding the result of a assassin bug. However, none of the pictures quite match so we were hoping you could help! Thankyou!
Signature: Zoie

Wheel Bug Nymph eats Tussock Moth Caterpillar

Hi Zoie,
You are correct that this predator is an Assassin Bug, but it is a diverse family.  More specifically, this is a Wheel Bug and it is an immature specimen that has still not developed its distinctive cog-like crest.  The prey in your photo is a Tussock Moth Caterpillar in the genus
Orygia which you may verify on BugGuide.

Letter 6 – Spined Soldier Bug eats Monarch Caterpillar


Any idea the name of this specimen?
Can you help identify this caterpillar recently found munching on goldenrod leaves. Thanks. You might also be interested in the attached shot of a Monarch caterpillar recently done in by the stink bug lurking in the shadows.
Colin Freebury
Ottawa, Ontario Canada

Hi Colin,
We are thrilled to post your Spined Soldier Bug,Podisus maculiventris, one of the Predatory Stink Bugs, with its Monarch Meal. Here is a site with more information on this Predatory Stink Bug.

Letter 7 – Mantis eats American Dagger Moth Caterpillar


Dear Bugman,
Our garden is always chock full of Preying Mantis’. It took me three years, but I finally saw one eating something! Looks like he caught some sort of caterpillar and was sucking out the inners while holding him in his grasp. Quite an awesome show, I must say!
Cincinnati, Ohio

Hi Rich,
We have been meaning to post your wonderful image for several days, but we are constantly barraged by new emails and you got lost in the shuffle. We believe this is a Chinese Mantid, Tenodera aridifolia, but would welcome an expert opinion regarding the identification. The caterpillar is an American Dagger Moth Caterpillar.

Letter 8 – We presume another species of Stinging Rose Eating Caterpillar, Cecrops Eyed Silkmoth


We havent seen this one before
Thanks in advance for your help. This one was found on a rose bush in Payson, AZ at about 5,000 ft elevation. Length is approaching 3″. I have looked at a couple of sites and didn’t see any that looked quite like it. Your help is appreciated.

Hi Forrest,
We are going to check with some sources and we will get back to you regarding this probably stinging rose eating caterpillar. We wrote to Eric Eaton who supports our suspicion that this is a relative of the Io Moth in the genus Automeris. Additional web searching led us to BugGuide’s page of Automeris cecrops panima, the Cecrops Eyed Silkmoth.

Letter 9 – Wheel Bug Eats Caterpillar


Is this related to a Squash Bug?
I’ve seen this bug in large numbers around my vegetable garden near Dallas Texas. They often congregate in the sunflowers and are proficient fliers. They look similar to and I thought related to a squash bug. Thinking that I figured they were harmful to my veggies, so I would mash one whenever I got the chance. Until I saw this one. Seems to be quite helpful as he’s eating one of the worms on this ear of corn. But what is it?
Near Dallas, TX
Jerry D. Coombs, Wylie, TX

Wheel Bug eats Caterpillar
Wheel Bug eats Caterpillar

Hi Jerry,
Your predator is a Wheel Bug, and its resemblance to a Squash Bug is because the two are in the same insect order, but they are not closely related as they are in different families.  The Wheel Bug is in the Assassin Bug family.  We are pleased to add you photo to our food page section.

Letter 10 – Crab Spider eats Monarch Caterpillar in Canadian Milkweed Patch


Life (and death) in a milkweed patch
December 28, 2010
Location:  Manitoba Birds Hill Provincial Park, Canada
Hi Daniel:
Every July tens of thousands of people descend on Manitoba’s Birds Hill Provincial Park for one of Canada’s, and North America’s, oldest and largest folk festivals (we haven’t missed it for more than 30 years!). In 2006 I discovered the most impressive milkweed patch I have ever seen, wedged between a parking lot and an oak forest, and was thrilled with the abundant and diverse bug life I found there. To my dismay, however, I then watched the patch get systematically destroyed over the next few days as festival goers heedlessly drove and parked all over the patch in an effort to get closer to the shade provided by the adjacent trees. This is generally a ‘green’ crowd so I think it happened more out of ignorance than callousness, but the result was the same. When the same thing happened in 2007 I decided something needed to be done. So I contacted both park and festival staff to plead my case for the protection of this incredible island of diversity, particularly since it is located in the middle of a provincial park.

Milkweed Patch Saved

When we arrived for the 2008 festival I went straight to the patch and was delighted to see the whole area cordoned off, as it has been every year since. Unfortunately, 2008 was one of our coldest wettest summers in recent memory and the milkweeds were barely knee-high and not flowering. The next year was almost as bad, but in 2010 our glorious summer weather returned and the milkweeds were nearly chest high and flowering profusely – and the bug watching was spectacular! The attached photo of what I believe is a Xysticus punctatus Crab Spider finishing off a hapless Monarch caterpillar is one of my favourites from 2010. The other two photos show the milkweed patch after the 2007 festival, and protected in 2010. If you or any of your readers are interested, I have uploaded a collection of photos taken at this location since 2006 (with more to follow next year, I am sure). I am still working on some of the identifications and I am not certain about some of the ones I have inserted, so any comments or suggestions would be welcomed and appreciated. Regards.  Karl

Crab Spider eats Monarch Caterpillar

Hi Karl,
We love hearing how your conservation activism made a difference.  You did not attach any images, so we took the liberty of lifting a few from your web posting.  We might be interested in posting a few more butterflies and dragonflies if you give permission.  We especially love the Milkweed Meadow as an important and diverse ecosystem, and we recently created a unique tag for postings related to Milkweed.

Crab Spider eats Monarch Caterpillar

Thanks for bailing me out Daniel; I forget my attachments all the time. These were the files I was going to send but I am also fine with what you put up (although I suppose they don’t quite match the text).  Go ahead and borrow anything you like, or let me know if you have anything specific in mind. I have thousands of photos that I have been meaning to organize and perhaps upload, but I just haven’t been able to find the time. Perhaps next year.  Have a great new year! K

Destroyed Milkweed Patch in 2007

Thanks for sending additional images Karl.  We have posted the 2007 image with the mutilated Milkweed Patch to accompany the original posting.  We will let you know if we post any of your other wonderful images.

Letter 11 – Spined Soldier Bug nymph eats Caterpillar


Two to Tango
Location: near Athens GA USA
June 17, 2011 1:50 pm
Greetings, who are these two on the latch of the gate fence in northeastern Georgia, USA? Cheers!
Signature: Karen

Spined Soldier Bug nymph eats Caterpillar

Hi Karen,
Both individuals in your photograph are immature insects.  The predator is one of the Predatory Stink Bugs in the subfamily Asopinae, and we believe based on this image on BugGuide, that it is most likely in the genus
Podisus, though nymphs are often difficult to accurately identify.  As you can see from the information page on the genus Podisus on BugGuide, there are both light and dark forms of the nymphs, and yours appears to be a light nymph.  We believe the caterpillar is a Cutworm, a caterpillar of an Owlet Moth.

Hi Daniel,
Thank you, and glad to hear it was a beneficial (possibly a spined soldier bug I suppose). Here’s a similar picture of predator + caterpillar that I found afterreading your email: ; and then there are the beneficial assassin bugs:
It has been difficult in the garden for me to tell a beneficial from adestructive stinkbug at times, but tonight I saw the ‘black streak on winged membrane’  in a pic of the soldiered spine, which was helpful to learn ( ). I carry a magnifying glass in my garden bag and have my phone with Web access too; but sometimes, esp. in 90+ degrees, I simply capture whatever it is and try to look it up later to avoid squashing a beneficial anything. Eggs are difficult to discern, of course.
Tonight I noticed a primary hindrance to learning to ID bugs  is me not understanding what the description refers to, which will require more study than I have time for right now. But here’s the example, “single-spined humeral angle” (and I even know what a human humerus is, <smile>): at , there is this: “Adult predatory stink bug, Podisus maculiventris (Say). Not only is this predatory stink bug much smaller than Alcaeorrhynchus grandis (Dallas), but notice the single-spined humeral angle.”
Must close. Thanks again for the educational side trip. I have other bug pics that I’ll send sometime for your collections.
Best wishes,

Letter 12 – Running Crab Spider eats Caterpillar


anatus formicinus eating unidentified caterpillar
Location: Toledo, OH
March 21, 2012 11:13 am
Afternoon, Bugman.
Ran in to this guy while chasing snakes (to photograph, not to harm) and didn’t have the heart to lift the wood he was on to follow my snake friend. Pretty sure it is anatus formicinus, but after half an hour of digging around I can not identify my caterpillar. Ah well, it was still a wonderful sight!
Signature: Katy

Running Crab Spider eats Caterpillar

Hi Katy,
We believe you have correctly identified this Running Crab Spider, though we are correcting the spelling of the genus name which is
Thanatus.  There are some photos of Thanatus formicinus on BugGuide that look very similar.  We believe the caterpillar is most likely a Cutworm or Noctuid Caterpillar, or possibly a relative of the Tent Caterpillars, but we haven’t the time this morning to do that research.  This is a thrilling spring Food Chain image.

Letter 13 – Ants eats Giant Silkmoth Caterpillar


Subject: Spiny caterpillar
Location: Osa Peninsula, Costa Rica
March 27, 2014 3:26 pm
We came across this large spiny/fleshy caterpillar (being eaten by ants) in the Osa Peninsula in Costa Rica at the end of the dry season (middle of March). It was about 3 inches long. Do you know what it would have become?
Signature: Alison

Ants eat Giant Silkmoth Caterpillar
Ants eat Giant Silkmoth Caterpillar

Hi Alison,
Alas, this caterpillar appears to have already become all that it will become, food for Ants.  Were it not attacked, it should have transformed into one of the Giant Silkmoths in the family Saturniidae and the subfamily Hemileucinae, though we have not had any luck verifying the actual species.  We will contact Bill Oehlke to get his opinion.

Only a guess. Automeris postalbida. Color might be off due to near death.
Please always ask for more precise location before sending images. Saves me
time in looking things up. Different species, often very similar, can often
come from different locations. If I know location I might only have to
search through five files instead of fifty as I have species checklists for
most of South and Central America down to one level below national level..
Thanks for thinking of me.

Letter 14 – Predatory Stink Bug eats Caterpillar


Subject: Bug ID
Location: Cheektowaga, N.Y.
July 18, 2015 5:04 pm
Have not seen this bug before. Have searching to ID but no luck, but will keep trying.
Took the picture of bug on my rose bush eating small inch worm. My roses have not been good this year. Lot’s of chewy leaf insects & started spraying to late. I don’t like pesticides but was contemplating till seen this. Do not want to kill good insects.
Anyway any info would be appreciated.
I live in Cheektowaga, N.Y. 14043 just outside of Buffalo, N.Y.
Signature: Butch

Predatory Stink Bug eats Caterpillar
Predatory Stink Bug eats Caterpillar

Dear Butch,
Your reservations concerning pesticides are deserved because broad spectrum pesticides do not discriminate between pest species and beneficial insects.  Several years ago we were amused that Ortho Bug-B-Gone illustrated their product with an image of a Monarch Caterpillar.  Your predator is an immature Predatory Stink Bug in the subfamily Asopinae, and we believe we have matched it to a BugGuide image of an immature Stink Bug in the genus
Podisus, commonly called Spined Soldier Bugs.  One member of the genus is profiled on Featured Creatures.

Letter 15 – Immature Spined Soldier Bug eats Monarch Caterpillar


Subject: bug sucking on a monarch caterpillar
Location: SE Wisconsin
August 3, 2015 5:34 pm
Dear Bugman,
We have swamp milkweed in front of my parents’ house and the monarchs love it. For the first time ever, I found this bug sucking the insides out of one of the caterpillars. This was Aug. 3 at about 5 in the evening. I’m familiar with assassin bugs, but not ones like this. I didn’t kill it, but moved it to another part of the yard so it wouldn’t eat the other caterpillars too!
Signature: A.M.

Immature Spined Soldier Bug eats Monarch Caterpillar
Immature Spined Soldier Bug eats Monarch Caterpillar

Dear A.M.,
The predator is a Predatory Stink Bug, the Spined Soldier Bug in the genus
Podisus, and it is an immature nymph.  This is not the first time we have received an image of an immature Spined Soldier Bug eating a Monarch Caterpillar.

Letter 16 – Cuckoo Eats White Flannel Moth Caterpillars


Subject: Cuckoo for caterpillars (Food Chain)
Location: Louisa Co., Virginia, USA
August 17, 2016 10:24 am
I have a 9-year-old honeylocust which this year has the most glorious infestation of some apparently delicious caterpillars. I am an avid birdwatcher and have contented myself with mostly listening for the shy, elusive cuckoos that appear in my yard every year. However, for the past week they have not been able to stay away from this tree and the buffet the caterpillars are providing – as many as 3 cuckoos hanging around gorging themselves just outside my door. I’m not concerned about the tree – just a bit of minor defoliation, and it’s late in the season – but I sure hope that whatever bug this is decides to come back from now on so I can get such fantastic views of yellow-billed cuckoos!
Signature: Winston B

White Flannel Moth Caterpillar
White Flannel Moth Caterpillar

Goodness, Gracious Winston,
This one proved to be a far greater challenge to us than we anticipated.  We recall having identified this distinctive caterpillar species in the past, and we were relatively certain it was a Flannel Moth Caterpillar, so we searched our own archive.  We looked at hundreds of old postings, beginning with Asps and Flannel Moth Caterpillars, but we could not locate it.  We eventually found it on Walter Reeves Venomous (Poisonous) Caterpillars site where it is identified as a White Flannel Moth Caterpillar.  We then returned to our own site, but the most recent posting we had of a White Flannel Moth Caterpillar,
Norape ovina, was 2007, and that predated our site overhaul and recategorization method.  According to BugGuide:  “Caterpillar has stinging spines” but obviously, your Cuckoos are unaffected by the spines or venom.  BugGuide also notes:  “Species name ovina is Latin, meaning ‘of or like sheep'” and we suspect that might be a reference to their group grazing behavior.  We love your Food Chain images.

Cuckoo Eats White Flannel Moth Caterpillars
Cuckoo Eats White Flannel Moth Caterpillars

Letter 17 – Predatory Stink Bug Nymph eats Caterpillar


Subject:  What bug is this?
Geographic location of the bug:  Cincinnati,  ohio
Date: 08/28/2018
Time: 09:34 PM EDT
Your letter to the bugman:  Hi! We found this guy munching on some caterpillars on our kale plant.  Any idea what kind of big this is?
How you want your letter signed:  Ginja ninja

Predatory Stink Bug Nymph eats Caterpillar

Dear Ginja ninja,
The predator is a Stink Bug nymph and we have identified it as an immature Spined Soldier Bug, a member of the genus
Podisus, thanks to this BugGuide image.  According to BugGuide:  “preys on a wide variety of other arthropods, especially larval forms of Lepidoptera and Coleoptera. known to eat Mexican bean beetles, European corn borers, diamondback moths, corn earworms, beet armyworms, fall armyworms, cabbage loopers, imported cabbageworms, Colorado potato beetles, and velvetbean caterpillars.”  We will attempt to identify your Moth Caterpillar as well, but we are surmising that since it was found on kale, it is most likely an undesirable species.

Letter 18 – Giant Strong Nosed Stink Bug nymph eats Tussock Moth Caterpillar


Subject:  Insect attached to caterpillar
Geographic location of the bug:  Macon, Ga
Date: 06/19/2019
Time: 07:44 PM EDT
Your letter to the bugman:  Was curious what this insect is?
How you want your letter signed:  Evan S. Thomas

Giant Strong Nosed Stink Bug nymph eats Tussock Moth Caterpillar

Dear Evan,
Though most Stink Bugs feed on plants, those in the subfamily Asopinae, the Predatory Stink Bugs, prey on other insects and arthropods.  We quickly identified this Strong Nosed Stink Bug nymph,
Alcaeorrhynchus grandis, thanks to images posted to BugGuide.  The prey is a Tussock Moth Caterpillar.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. 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.

26 thoughts on “Caterpillar Predators: Who’s on the Menu? Exploring Natural Predation”

    • If you really want to try to save the Monarch Caterpillars but not harm the environment, you can hand pick and squash the Stink Bugs. That is our pesticide free recommendation. Beware as these are predators and they might bite a human if provoked. We recommend using thick garden gloves for the task to reduce the potential for a bite.

  1. My two cents here would be that Thanatus formicinus is not a wolf spider, and I only point that out because the spider pictured I would say more resembles a wolf spider, in terms of the shape of its head. But I’m no expert, just my observation. Also, I’m curious if the spider actually attempted to eat this or not, since in the picture it appears to be more just feeling it out.

  2. I just found 2 stink bugs snacking on ‘my’ baby monarch caterpillars. I had no idea that anything ate Monarch caterpillars at all – I was very surprised.
    Is there anything I can do other than pick these greedy gobblers off of the milkweed?
    Will they kill a Monarch in its chrysalis?
    A few years ago it looked like I’d have a bumper crop of Monarchs, but I found quite a few had turned black – sort of mummified while still caterpillars. Could it have been stink bugs?

    • Monarch Caterpillars might also be parasitized by certain wasps. We are sorry to hear about your losses, but hopefully enough caterpillars will survive. We do not know of Stink Bugs attacking the Chrysalis.

  3. That’s an intimidating genus name, especially for a spider! Wikipedia seems to indicate that it is in in fact a variant spelling of Thanatos, Greek god of death. (For the mythically interested: Hades, lord of the underworld, was his boss.)

    • Makes one wonder why this particular spider genus is associated with the Greek god of death while other spiders are not. Quite curious.

  4. Joshuallen: One could wish you had looked again at your second message before posting. That’s up in Worst Possible Typo range. 😉

  5. I have lived in Lynchburg, VA for 35 years and this is the first time I have ever seen one of these. My husband and 13 year old son have both been stung this year.

  6. Today, Sept. 6, 2018, I witnessed a stink bug of some sort attacking s monarch chrysalis. It had its long nose stuck inside the chrysalis. I wished I had taken a photo of it before sending it on its way to feed somewhere else.
    PS. I live in Sundridge, ON, Canada

    • I witnessed this as well and today the chrysalis looks dead. It has some discoloring near the top part of the chrysalis and the area is black where the stink bugs pointy mouth was.

  7. Today, Sept. 6, 2018, I witnessed a stink bug of some sort attacking s monarch chrysalis. It had its long nose stuck inside the chrysalis. I wished I had taken a photo of it before sending it on its way to feed somewhere else.
    PS. I live in Sundridge, ON, Canada

  8. Yesterday, I saw a stink bug nymph near a monarch chrysalis. It has its pointy mouth at the top part of the chrysalis. Today the chrysalis has some discoloring in the top area of the chrysalis. Can a stink bug nymph kill a monarch butterfly while in a chrysalis?

  9. It’s June 29, 2020 in Hermosa Beach, CA (a few miles south of LAX). I just witnessed some sort of black jumping spider eating a Monarch caterpillar; the spider scurried away before I could capture a cell phone image. Thanks for your info (I discovered after googling). I would never have guessed the butterfly had “such enemies”. I will keep an eye out for future encounters.

  10. Will stink bugs eat the entire chrysalis? I had two that were destroyed overnight in my screened in butterfly garden. One is completely gone and the other is 2/3 eaten w dark remnants smeared around.

  11. Yes, they do sting! For years before I limbed up the trees, I’d feel a searing pain while mowing underneath overhanging branches… and I never found the culprit. After you identified these, I learned not to go near them even in open-toed shoes. It’s not fun to step on them either! (By the way, the stings never caused a rash or irritation, just very unpleasant for ten minutes or so.)


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