Simple Steps. Big Impact.

Tobacco Hornworm Image credit: Lenora Larson

Have you ever wished you had an easy answer for how to control hornworms in your prized vegetable garden?

The answer may just surprise you!

Before you jump to the solutions, I recommend that you read this quick article from Dave’s Garden to learn more about the hornworm. The Tomato Hornworm: Friend or Foe?

And you may find this information from National Moth Week to be really helpful too.  

 Solution #1: Plant a sacrificial garden just for the hornworms

That may sound a little crazy considering you probably already know that tomato hornworms (and the related caterpillar, tobacco hornworms) can be really destructive!

They eat the leaves on your tomato plants and, of course, reduce your production of tomatoes.  They eat other plants in the nightshade family too including peppers, eggplants, and potatoes.

So what is the compassionate, nature-connected solution for dealing with tomato hornworms to keep your tomatoes, peppers, and potatoes healthy so that you and your family can enjoy the bounty of your garden?

Ironically, the best thing that you can do to control tomato hornworms is to create habitat for them on the other side of your yard.

Here’s what you do:

Pick those caterpillars off the “good” tomato plants and move them over into another less maintained area in your backyard away from your garden and where you have planted some extra tomato plants or thrown some tomato seeds, along with other sacrificial plants in the nightshade family. 

Helpful hint: to move them, cut off the leaf they are on if possible, because they hang on so tight, sometimes you will pull their prolegs off! They are like suction cups!

Call this area your “pollinator garden” and let the caterpillars eat away!

Here’s a link to inspiring gardening philosophy and clear examples from my friend, Lenora Larson, The Butterfly Lady from her “Butterflies in Our World” Series: In Praise of Tomato Hornworms.

If you’re squeamish about picking the caterpillars up – they can be over 4” long with a little soft and pliable “spike” on their butts – I don’t blame you!  So you can either cut off the stem they’re on and carry the whole stem over to your pollinator garden – or better yet, hire your neighborhood kids and pay them 50 cents per hornworm to move them!

They’re Gorgeous

And while you’re moving the caterpillars, be sure to take few moments to really look at them.  Their patterns, coloring, and shape are fascinating and their appearance changes depending on the maturity of the caterpillar.  

If it has a red spike then it’s the tobacco hornworm; if it’s black, it’s the tomato hornworm.

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 Solution #2: Repel them with companion plants

Here’s a method to put a plug of chewing tobacco near the roots of your tomato plants to repel the caterpillars.  Planting Tomatoes to Prevent Tomato Worms.

And SFGate lists Companion Plants to Discourage Tomato Worms.

Please comment below if you’ve tried repelling them with companion plants and let us know how it’s worked for you.

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 Solution #3: Bring them inside & raise them

Bring the caterpillars inside and rear them to the adult moth stage and then release these hummingbird moths to flit around and pollinate your garden!  (Of course that means you may have more caterpillars to contend with later, due to the abundance of eggs laid by your now-mature babies – but more about that below – think BIRDS!  Bottom line, more caterpillars can be a GOOD thing!)

Breeding them inside is a masterful way to teach kids about a whole slew of topics from nature!

Here’s a great article about how to raise them: It’s Hard to be a Hornworm from Normal Biology.

And another from ClubFauna: Breeding Hornworms.

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 Go Deeper

Why Not Just Kill Them?

So what’s the point? Why wouldn’t you just smash them or drown them as most articles and videos online recommend?

Well, we’ve all been taught that there are beneficial insects and then there are, well, pests.  

So try to reconcile why no one ever taught us that sometimes the babies of the beneficial insects are ones we’ve been taught to call pests?  

You can’t have the adult without its babies, right?  If you kill the caterpillars, you are destroying future adults.  

So who are the adults?

If the hornworm caterpillars have the right food to eat (and they only eat their own “host plants” –  leaves of tomato plants and other plants in the nightshade family) and if they have the right habitat, protected from the elements and birds, they turn into this really glorious furry hummingbird moth. Some people call it a sphinx moth or hawk moth.

These multi-colored moths are night pollinators who have really long tongues – up to 10 inches long.  They specialize in pollinating deep-throated flowers like morning glories, foxglove or beardtongue, bee balm, and petunia.

They hover like hummingbirds but can also fly sideways to escape predators.

And their buzz sound is mesmerizing!.  

See them in action in the videos Sphinxes are Back and White-lined Sphinx Moth Hummingbird Loving My Super Petunias!

So if you want beneficial pollinators in your garden you need to provide for both their immature as well as their adult needs.

What about Organic Pesticides?

If you want to understand a little bit about the concept of using organic pesticides, watch GrowOrganic Peaceful Valley’s How to Get Rid of Tomato Hornworms.  

This organic gardening video gives some good methods for controlling hornworms in a larger garden with some advice on not using pesticides, but there is still a lot of killing going on, so my advice is to listen to their advice and decide for yourself where your approach to compassion melds or diverges from your desire to maintain your plants or support declining populations of pollinators.  

One of their recommendations is that you till the soil between tomato-growing seasons. Understand that tilling the soil kills the larva, meaning, it kills the immature stage of the hornworm before it can mature to be a threat to your tomato plants.  So if you want to benefit the adult stage pollinator, the hummingbird moth, you won’t accomplish that by killing its immature larva …

As you watch the video, remember that the word “pesticide” means, literally, “to kill pests”.  

Using organic products may have more nature-centered and fewer harmful chemical components than non-organic products, but all pesticides will kill or sicken all insects and other critters that walk, crawl, lick, lay eggs, or nibble on the plants. And these sick or dying insects will negatively impact any other critters (like birds!) who eat them.  

Unintended Consequences

Many chemicals that were developed with all good intentions have been found to have unintended widespread consequences.

If you want to know more about the impact that insecticide spraying has on our ecosystems, I highly recommend that you read about Rachel Carson and her groundbreaking book, Silent Spring, published in 1962.  Her book and insightful testimony to Congress, in the midst of her debilitating treatments for breast cancer, led to banning insecticide spraying of DDT because its use sent our bald eagles and other falcons into near extinction.  Rachel Carson is known as the mother of the modern environmental movement and was instrumental in the creation of the Environmental Protection Agency in the United States.

Why Population Decline in Pollinators is Important

According to this Oct. 2017 study, “Are pollinating hawk moths declining in the Northeastern United States? An analysis of collection records“ published on ResearchGate, “declines in moth diversity and abundance could lead to disruptions in the plant communities they pollinate.”

From this study:

“Possible causes of declines in hawk moths include climate change, which might cause a mismatch between emergence of moth larvae and host plant leaf out; loss of habitat including host plants; forest succession, which has led to long-term compositional changes as northeastern U.S. forests recover from 19th century clearing for agriculture [36], [37]; increasing levels of artificial lights at night [14]; an introduced parasitoid fly (Compsilura concinnata; Tachinidae) [38]; and changing agricultural practices and land use that have caused declines in hosts available for hawk moths with larvae that feed on crop plants [33]. Considering the importance of hawk moths in their ecosystems and the diversity of threats they face, the absence of monitoring data is concerning because declines could be widespread without the conservation community having a means to detect them.

Inferred population trends

Using existing records of hawk moths in museum and private collections over a 112-year period, we were able to detect statistical declines in eight species of northeastern U.S. hawk moth pollinators, or 38% of the species for which sample sizes were sufficient to allow analysis. Two additional species declined or disappeared altogether from portions of the study area, and a third, Sphinx canadensis, may have declined in the portion of its range that overlaps the study area. Thus, as many as 44% of the species examined appear to have declined in at least part of the Northeast. Just four species, 19% of species with sufficient sample sizes, increased over the study period.”

Let me rephrase that in English:

As beloved naturalist John Muir famously wrote in 1911 in My First Summer in the Sierra,

“When we try to pick out anything by itself, we find it hitched to everything else in the universe.”

Everything is connected.

We humans have evolved to be very, very good at rearranging the landscape to what we think is to our benefit.  Considering just the tomato crop, I invite you to delve deeper into the interconnectedness of those spiky and ginormous hornworms to their broader importance to our ecosystems.

So How Is It All Connected?

Let me bullet-point this so I can wrap my mind around it – and hopefully, so can you:

  • Basic premise of healthy humans: We need clean water to drink and clean air to breathe.
    • Clean water comes from diverse and abundant plant, prairie, and forest ecosystems that prevent flooding and erosion and that filter chemicals during large rain showers. (There’s way more to it than that, but for the sake of this article, that’s a good start.)
    • Clean air also comes from a robust system of forests and plants.  Remember that plants exhale oxygen? Which we kind of need. And trees and plants inhale carbon dioxide?  Which we humans produce in abundance!
  • For plants, prairies, and forests to stay healthy, they need to reproduce.  All plants have their own unique ways to reproduce so that they, or their progeny, can continue to thrive.  
  • This reproduction can come from seed dispersal.  Ever see a squirrel bury an acorn? Have you blown the silky bloom of dandelions?  That’s dispersal of seed! (Be sure to watch my friend Marva Weigelt’s delightful lesson on creating the glorious sound of the Dandelion Horn – her first viral Facebook post and a hoot and a half!)
    Image credit: Marva Weigelt
  • The seeds of some plants are embedded in the fruit the tree or plant produces (like tomatoes – remember the point of this whole article?)  The seed will sometimes be hidden within the fruit – think of apple seeds.
  • In order for most plants or trees to produce fruit, their blossoms need to be pollinated – that’s right – by pollinators!  Did you ever cut an apple in half and notice that only some of the seed jackets contain actual seeds?
Honeybee pollinating apple blossoms – Image Credit: Heartland Honey

The ones that are empty mean that some of the apple blossoms were not pollinated.  So, again, thinking about the concept of “it’s all interconnected”, if the apple is to produce the most seed it can, then all of its blossoms need to be pollinated by a healthy population of pollinators!  

  • The Hummingbird Moth is a beneficial pollinator; not of apples or dandelions or oak trees, but they are still beneficial pollinators for the plants they specialize in, such as the morning glories, foxgloves, bee balms, and petunias.  These plants offer nectar, pollen, and habitat for lots of insects and are an important component of a healthy prairie.
  • There are compassionate ways you can grow tomatoes that will support populations of pollinators and still give you the delicious produce you hope for from your garden.

You Can Make a Difference

What are you able (and willing) to do to deal with the caterpillars that need to eat your vegetable plants in order to survive?  

How can The Resilient Activist help you incorporate compassionate gardening into your vegetable bed? What do you need support with to make this change in your life?  

Post your questions, answers, and ideas below and let’s talk…

Oh Yeah, and What’s This Article Got To Do With Birds?

So how could gardening for tomato hornworms bring more birds to your yard?

There’s just one bullet-point:

  • if you want to have birds in your yard, you have to feed them.

You may think, “But I have bird feeders out – I feed them all the time!”

In the same way that the Hummingbird Moths need to have the required food (nightshade plants) to raise their young, so do birds!  

What Do Baby Birds Eat?

Even if the adult birds are seed-eaters, their newly-hatched babies need protein! The most preferred food for breeding adults as well as their baby birds, like downy woodpeckers, Baltimore orioles, bluebirds, flycatchers, and sparrows are fat, juicy caterpillars – like the tomato hornworms.

So if you garden for tomato hornworms from a nature-connected perspective, you’ll automatically support habitat for the birds that will come eat them. The more caterpillars you have in your yard, the more food you have for baby birds.

That John Muir.  He knew his stuff!

In this scenario there’s no reason to use any chemicals or dish soap or to stomp on anything!

You’ll create a safe environment for insects, birds, and humans alike!  

Well, except for those poor hornworms that morph into bird food … and, well, that’s just the cycle of life!

  • Who do you know that would be interested in this topic?  Please share the URL with them!
  • What changes can you make to your gardening tasks to support the caterpillars that want to eat your plants?  
  • If you have children, how could explain this article to them and get them involved in helping in the garden?

Post your questions, answers, and ideas below and let’s talk…

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Resource List

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The Resilient Activist

The Resilient Activist enjoys sharing inspiring and nature-aware content from around the globe.  Hope you've enjoyed this article!