Ten Pound Tomato Grow Organic – Eat Better

July 29, 2010

Don’t Let Tomato Hornworms Ruin Your Tomato Harvest

Filed under: Garden Pests,Newsletter Archive — Tags: , — Perry Droast @ 11:00 pm

[ad#Adsense top left post]Tomato Invasion Newsletter #3

Crush ’m, Cut ‘m, or Dunk ‘m…Before the Green Monsters Destroy Your Garden

Tomato and tobacco hornworms wreak havoc on your tomato plants in short order if you let them. They’ll eat the leaves, green tomatoes, and start on the branches if left alone. And they grow fast. I don’t think they ever stop eating. They seem to grow an inch a day or more and they get a big around as your thumb.

Today I found two of them munching happily on my prized heirloom Cherokee Purple tomato plant. Without thinking I picked off the first one I spotted and immediately crushed it with a handy rock. Then I spotted the second one and picked it off the plant too.

Then I decided to take some photos so I put it back on the plant and ran to find my camera. When I got back he was upside down headed for cover. I took a few photos before crushing him right next to his buddy.

There’s a good way and a bad way to crush a hornworm

And you need to know the difference. If you momentarily lose your mind and toss them on the concrete sidewalk near your garden for easy and effective final rites, you’ll only do it once. The green stain doesn’t wash off easily and the remains of the caterpillar stick to the bottom of your shoe too. Hornworms are very squishy, full of green liquified slime, and hard to crush by hand. So my first reaction was to crush them on the nearest sidewalk. I only did that once.

As you may be able to tell, my favored method of ridding my garden of hornworms is death by crushing. It sounds terrible but it’s not. At least for me it’s not. For them, at least it’s quick. There always seem to be a rock or dirt clod big enough to place on top of the hornworm so I can do a quick and painless crushing. I do it right in the dirt of the garden figuring they ate part of my garden so now what’s left of them can feed it.

If it sounds too gruesome you may need to have someone else in the family assigned to hornworm patrol. Because tomato or tobacco hornworms don’t discriminate. They’ll eat your tomato plants to sticks if you let them. And hornworms eat anything in the nightshade family like potatoes and peppers too.

Hornworms eat anything in the nightshade family

Here’s a rundown of the common plants hornworms eat. Just about any member of the nightshade or potato family will do. This includes datura (jimson weed), mandrake, deadly nightshade (belladonna), capsicum (paprika, chili pepper), potato, tobacco, tomato, eggplant and even petunias.

Personally, I’ve never seen them eat anything except tomatoes and peppers. I grow petunias almost every year and I’ve never seen a horn worm munching on one. I included it because if you don’t have any of their preferred food, they’ll just as gladly eat what you’ve got.

Braconid wasps help control hornworms

Fortunately, there are a couple ways to help control the tobacco and tomato hornworm. The parasitic braconid wasp lays its eggs in the hornworm which provides the larvae a perfect environment grow and develop. If you see a bunch of white egg-shaped pods on the back of a hornworm don’t crush it. Pick it off the plant and place the hornworm in a glass jar with the lid off. It should allow the hornworm to live long enough for the larvae to hatch out and go find some more hornworms so they can procreate like their parents did.

When braconid wasp larvae mature and leave the hornworm, the hornworm dies so it won’t turn into a moth which is of course what all good (and in this case – bad) caterpillars do. In this case, the natural biological process helps control the spread of this voracious pest in your garden.

Control hornworms using biological control – BT

You can also stop the hornworm from destroying your tomatoes and peppers by spraying a natural biological control Bacillus thuringiensis, var. kurstaki (BT) sold in good garden centers or found online. BT won’t stop full-sized caterpillars from eating though it controls small ones quite well. Once you apply BT on your your plants, the worms eat it along with the plant. Once they’ve eaten a little, the BT causes them to stop feeding and they eventually starve without reproducing.

BT is effective against a wide range of garden worm pests so if you’re spraying your tomatoes and peppers, go ahead and spray the rest of your garden too. Pay special attention to your brassicas like broccoli, cauliflower, cabbage, brussels sprouts, bok choy, among others. Because the brassicas often attract cabbage worms and cabbage loopers the BT will protect them as well.

The no-crush way to humanly kill a hornworm…

And any other garden pest you can hand pick too. Make up a small pail of soapy water using dishwashing detergent. Drop any pest including any hornworms you catch into the water and the soap makes sure they won’t swim out and re-invade your garden.

Because hornworms get big fast, handpicking is the general method I use to control them in my garden. I go on a daily patrol checking my plants thoroughly.

How to spot a hornworm…

The method I use to find hornworms is three-fold.

Look for obvious leaf and fruit damage…hornworms grow fast and eat almost continuously leaving lots of obvious damage in their wake.

Look for hornworm droppings…hornworms leave dark green (almost black in appearance) droppings on the leaves and ground below where they are munching. They don’t take time out to look for a toilet.

Look for the hornworms themselves…this can be a little tough because they are camouflaged extremely well.

How do I know if I have tobacco hornworms or tomato hornworms?

Hornworms are very easy to tell apart. A tobacco hornworm has seven diagonal white slash marks on its side and a red tipped tail appendage. A tomato hornworm has eight v-shaped marks on its side and a black tipped tail.

Knowing the difference won’t change how you protect your garden from this pest though. Both types of hornworms eat the same plants for the most part and they look very similar to the untrained eye. And they both eat like, well – hornworms, and can quickly wreak havoc on your tomatoes if you don’t watch out.

That ugly thing tried to bite me!

Yep, that’s what it looks like when you grab a hornworm. If you’re afraid of getting bit, just make sure you grab them just behind the head as you pull them off the plant. Watch out for your plant too as you pull them off.

Their little legs (that’s what I call them) grab  onto the plant very well. So don’t just grab and yank. Pull them off the plant in a controlled manner and hold onto the plant if it looks like the plant will break as you pull.

It is a little disconcerting at first to grab them though because they certainly appear to be trying to bite you. So I grab them behind the head and they simply can’t reach me that way. And they can’t really bite you anyway. Their mandibles are small and can’t do any real damage to your hand.

If you really don’t want to touch them, carry a pair of garden scissors and just cut them in half. It’s a little messy but you don’t have to touch them and they won’t grow into two worm either. Or use a stick to pick them off the plant and toss on the bird feeder. Your local bird population will love the organic fare you’ve provided.

Hornworms life cycle means 2 to 4 rounds depending on your climate

If you live in Florida, you may see as many as four different rounds of hornworms munching and crunching through your garden. That goes for any place with warm and long growing seasons. In colder climates, two life cycles are more typical.

No matter. It’s not hard to control them as long as you go on a daily or at least every other day patrol. You need to pick your ripe tomatoes anyway so take a quick look around for the telltale signs of hornworm infestation as you pick.

If you see hornworm damage, don’t panic

Simply find the camouflaged worm and get it out of your garden. You can crush them like me. Or feed them to the birds if you have a feeder. Give them a soapy water bath, or cut them in two.

Your plants will recover. And you’ll still get to enjoy all those wonderful tomatoes.


  1. Thank you for the article. I pick them by cutting off the leaf they are attached to, then cut them in half with scizzors. I grown tomatoes on my deck in pots. I watch the decking every day to detect droppings. What amazes me is a new worm will appear overnight, up to 3″ long. Not sure if I’m just missing smaller droppings, but I doubt it. Can they really grow that large overnight?

    Comment by Larry Miner — July 4, 2011 @ 7:41 am

  2. Thank you! You have no idea how much help your advice on how to rid my garden. I chose the path of crushing the little devils it works best for me!

    Comment by laura — July 13, 2011 @ 6:43 pm

  3. Larry,

    I’m not sure just how fast hornworms grow, but I sometimes swear they become adults overnight. I do spot a smaller one from time to time. They have an enormous appetite and will eat a large section of plant in a couple days if you let them.


    Crushing is easiest for me too. I don’t always have a pair of garden scissors with me to snip them in half. Besides, once you crush them into the dirt, they help feed the soil which is always a good thing.

    Comment by Perry Droast — July 19, 2011 @ 11:47 pm

  4. best information that i have had. barn critters and just for the information took 2 and put them in a jar for grand kids to see, i have never seen anything eat and grow so fast. but sure have learned to patrol daily. thanks for the info.

    Comment by Rita Naase — June 17, 2013 @ 7:18 pm

RSS feed for comments on this post. TrackBack URL

Leave a comment

Powered by WordPress