Manduca sexta tobacco hornworm on tomato

What is that giant green thing on my tomato plant?

Last summer I was in my tomato patch, admiring the ripening tomatoes and pruning off excess growth, when something caught my eye. Now I should pause and explain that I grow a lot of tomatoes; 17 plants last season, in fact. And they aren’t little tomato plants—I love to grow heirloom tomatoes, many of which get to be more than 8’ in height. So I should probably have said that I was wandering through my tomato forest, when something caught my eye.

It was an unusual white stripe on the leaves of one of my tomato trees, right at eye level. The sun was high and bright, casting harsh shadows, so I couldn’t quite make out what I was looking at.


I peered in for a closer look…eek! That was no leaf, that was a tomato gardener’s nemesis—the tomato or tobacco hornworm!

These huge caterpillars have a correspondingly large appetite, and can defoliate a tomato plant (i.e. eat all of its leaves) if left unchecked.

I first thought this particular specimen was a tomato hornworm, but a bit of digging revealed that it was actually a tobacco hornworm. While different, their habits are similar enough—they both feed on plants in the Solanacaea family—tomatoes, potatoes, and tobacco. Tomato hornworms are marked with 8 white v’s, tobacco hornworms are marked with 7 white stripes down either side. Tomato hornworms have dark blue or black horns on their backs (sort of a tail) while tobacco hornworms have red horns. You can clearly see the red tail and white stripes, not v’s, in the above photo.

Both the tomato hornworm and tobacco hornworm can seriously damage or even kill a tomato plant. Fortunately, given their size, they’re easy to spot (even in a tomato forest) if you inspect your plants regularly. Also,  you’re not likely to have a large infestation of them–I’ve only ever found one or two in my garden during a season–and most years I don’t find any. Despite having multiple legs, hornworms don’t move quickly, so hand picking them and disposing of them is the best method of control (drowning in a pail of soapy water is recommended by some gardeners). You do not need to apply a spray or powder or get into any of that nasty stuff.

While I don’t like what these critters do to a tomato plant, I do find them quite fascinating to look at. Not only do they have white stripes but they also have circular white and black markings that look like eyes all the way down their sides—I presume this is to confuse predators. If allowed to carry out their life cycle they turn into large moths.

Have you ever been surprised by a tomato or tobacco hornworm in your garden?






  1. Eugene K on January 25, 2017 at 12:27 pm

    Scary monsters! That creature is right out of a bad sci-fi movie. Circle the wagons and take up arms, gardeners.

    • Jennifer on January 25, 2017 at 9:18 pm

      Haha!’Tis true!

  2. Paul on July 30, 2018 at 5:47 pm

    This was very informative,Thanks!

    • Jennifer on July 31, 2018 at 11:23 pm

      Glad you found it helpful Paul–thanks for letting me know!

  3. Anne Noah on June 28, 2023 at 9:10 pm

    I was getting a hornworm off the tomato plant and green stuff squeezed out of its butt and landed In my eye! I washed it out and put eye drops in but my question is can that stuff damage a human eye?

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